Diesel Particulate Study 

October 1983 

Standards Development and Support Branch 

Emission Control Technology Division 

Off ice of Mobile Sources 

Office of Air and ·Radiation 

U.S. Environmental Protection Agency 
Diesel Particulate Study 

October 1983 

·standards Development and Support Branch 

Emission Control Technoloav Division 

Off ice of Mobile Sources 

Office of Air and Radiation 

U.S. Environmental Protection ~gency 
?ART I 

INTRODUCTION 

TABLF. OF CONTENTS 

EVALUATION OF CONTROL OPTIONS 

PART II -SUPPOR~ING TECHNICAL ANALYSES: 

Chaoter 

1 •. Technology 

2. Emissions Impacts 

3. ~ir Quality Impact and Population Exposure 

4. Visibility Assessment 

5 •. Cancer Risk Assessment 

~. Non-Cancer Health Effects 

7. Soilina Effects 

8. Economic Impact 

9. Cost Effectiveness 

11). Sensitivity 

-~P'!=>endix A 

Pace 

l 

6 

1-1 

2-1 

3-1 

4-1 

5-1 

6-1 

7-1 

8-1 

9-1 

10-1 

A-1 
Part I 

INTRODUCTION 

I. Puroose of the Study 

EPA's study of the costs and environmental effects of the 

control of diesel particulate emissions and their regulation 

has been underway for; some time. Emission standards for 1982 

and later diesel-powered light-duty vehicles and light-duty 

trucks (light-duty diesels) were promulgated in 1980. Similar 

standards for diesel-powered heavy-duty diesels were proposed 

in 1981. 

The pertinent data on both the costs and benefits of 

diesel particulate control have been constantly changing over 

time. This is particularly true of the last two to three years 

since the time of the rulemakings mentioned above. Emission 

control technology h·as been constantly evolving, changing both 

baseline emission rates and the ability and costs of further 

control. In addition, a number of cancer-related health 

studies on diesel particulate have been completed in the last 

two years, allowing an assessment of oenef its in th is area 

which was not previously possible. Data and project ions in 

other key areas have also been changing, resulting in a need 

for EPA to reexamine its regulatory position. 

Recent regulatory activity by EPA has reflected these 

changing circumstances. In the light-duty area, EPA has 

promulgated a delay of the more stringent, 1985 standards until 

1987, leaving in place the current 1982 . standards through 

1986. This action is based on the fact that a new control 

technology could not be a(?plied fleet-wide for the 1985 model 

year, but will require two additional years of effort. This 

new technology is ref er red to as a trap-oxidizer and produces 

substancial reductions· (i.e., greater than 50 percent) in 

diesel particulate emissions. In the heavy-duty area, EPA has 

announced its intention to repropose its 9articulate standard 

along with the NOx standard proposal, because of the 

interelationship between NOx and particulate control. This 

combined proposal should enable this interaction between the 

two pollutants to be better assessed and facilitate a more 

orderly standard setting process. 

The purpose of this study is to provide a comprehensive 

assessment of the costs and environmental effects of the 

control of diesel particulate emissions and to recommend a 

regulatory strategy for their control. As such, this study 

expands, updates and combines the Regulatory Analyses 

supporting the 1 igh t-du ty d iese 1 ( LDD) part icu late final rule 

and the heavy-duty diesel (HDD) ?articulate proposed 
2 

rule. [1,2] The study will identify current and future diesel 

part icu late emissions and exposure levels, assess the heal th 

and welfare impact of diesel particulate, and estimate the 

costs of controlling diesel particulate emissions to various 

levels. The study will then integrate these aspects of diesel 

particulate control and develop, evaluate, and recommend a 

regulatory control strate9y. 

This study does not at tempt to economica 11 y quantify the 

changes in heal th or welfare that are associated with various 

diesel oarticulate control strateqies. Such an economic 

quantification of benefits is beyond the scope of this report, 

but has been performed for various diesel particulate control 

strateqies under contract to EPA.[3] The reader should consult 

this document and others in the literature for information on 

the economic benefits of controlling diesel particulate. 

Four regulatory scenarios are examined in this report 

which cover a wide range of technological stringency. The 

least str in9ent control scenario (the relaxed scenario) would 

require no further control from LDDs and only very modest 

reduct ions from HDDs, represent inq the least s tr ingen t degree 

of control conceivable. The next most stringent scenario (the 

intermediate scenario) would reauire the aoplication of 

advanced non-trap technology. By their nature, these 

techniques are quite cost effective and this scenario 

represents a modest degree of control that should be available 

at low cost. The third scenario (the base scenario) consists 

of the current trap-based standards (i.e., the 1985 LDD 

particulate standards and that proposed for 1986 HDDs). This 

scenario ?rovides more control than that achievable through 

non-trap technoloay, but will be more costly and less cost 

effective than the second scenario due to the use of trap 

technoloqy. The four th scenario (the str inaent scenario) 

reoresents the greatest degree of control presently 

conceivable. \Jearly all vehicles would be equi;iped with traps 

under this scenario. These scenarios are summarized in Table 1. 

As an averaging concept has already been promulgated for 

compliance with the 1987 LDDV and LDDT trap-based particulate 

standards, the flexibility it provides will be presumed here 

for the base, intermediate, and stringent scenarios. As it is 

li~ely, but not certain, that a similar program will be 

proposed for HDDs, both averaging and non-averaging situations 

will be examined for the base scenario. 0nly averagin9 

situations will be considered for the HOD intermediate and 

stringent scenarios. qowever, under the HDD stringent 

scenario, all vehicles are likely to require traps, so 

averaqing does not add much flexibility. 
* 

** 

3 

Table 1 

Emission Control ~cenarios* 

Relaxed Scenario: 

LDOV (a/mi) 

LOOT (g/mi) 

HDOV (g/Bf-lP-hr) 

Intermediate Scenario: 

LODV (g/mi) 

LOOT (g/mi) 

'RDDV (g/BHP-hr) 

Base Scenario: 

LDOV (g/mi) 

LOD'l' (g/mi) 

Hnnv (g/BRP-hr) 

Stringent Scenario: 

LDDV (a/mi) 

I,DD'T' ( g /mi) 

f1DDV (a/BFP-hr) 

Particulate Standards 

Implementation 

Level* Date** 

Current Levels(NA) 

Current Levels(NA) . 0.6(~A) 

0.30(A) 

0.35(A) 

0.40(A} 

0.20(A) 

0.26(A) 

0.25(NA & A) 

n.08(A) 

0.105(A) 

O.lO(N/A) 

1988 

1987 

1987 

1988 

1987 

1987 

1<188 

1987 

1987 

1988 

Range of 

NOx Standards 

1.0, l.S, 2.0 

1.2, 1.7, 2.3 

1.0, 1.5, 2.0 

1.2, i.-, 2.3 

1.0, 1.5, 2.0 

1.2, 1.7, 2.3 

1.0, 1.5, 2.1) 

1.2, 1.7, 2.3 

(.~) :Tleans averaqina proqram available, (°'.'~A) means no 

ave::-aging orogram available. Also, all control scenarios 

were evaluated for their incremental e:fects beyond 

continuing the relaxed scenario. 

~he implementation dates for the various RDD standards 

analyzed in Part II were arbitrarily chosen at 1988 for 

simplicity. In reality, as discussed in Part I most of 

these standards would likely be implemented about 1990, 

except for the 0.6 g/BRP-hr standard which appears 

feasible by 1987. 
4 

A factor that must be considered when assessing the 

ability to control diesel particulate is the level of the 

applicable NOx standard. In general, as NOx emissions are 

reduced, engine-out levels of particulate increase. Thus, 

under a stringent NOx standard the technically feasible level 

of particulate control (without the use of aftertreatment 

devices) will be higher than under a lenient NOx standard. 

Because there is currently some doubt as to what the NOx 

standards will be in the years covered by this study, three 

different LDDV standards were evaluated: 1) 1.0, 2) 1.5, and 

3) 2.0 g/mi. As the NOx standard for LDDTs is directly 

influenced by that for LDDVs, this study will also evaluate the 

effect of the three LOOT NOx standards equivalent to those for 

L D DV s : 1. 2 , 1. 7 , and 2 . 3 g Im i. 

The question of the appropriate NOx standard for HDDs is 

dealt with in a more straightforward fashion than LDDs, since. 

the level of the standard will be set by EPA. While Section 

202 (a) (3) (Al (ii) of the CAA requires a NOx standard of 1. 7 

g/BHP-hr, this level is not feasible for HDDs. Thus, EPA must 

set a revised NOx standard under the requirements of Section 

202(a) (3) (B), which are very similar to the requirements 

specified for the HOD particulate standard in Section 

202(a) (3) (A) (iii). Thus, under all scenarios, the HDDV NOx 

standard is treated as a variable and identified in much the 

same way as the particulate standard. 

II. Organization of the Study 

The study has been segregated into two parts. Part I of 

the study contains this introduction and an overall evaluation 

of control. options. Part II contains the supporting technical 

analyses. 

In addition to describing the context, purpose and 

organization of the study, this introduction describes the 

control scenarios evaluated and the diesel sales projections 

used throughout the analysis. The following "Evaluation of 

Control Options'' summarizes the cos ts and environmental 

benefits of the various diesel part icu late control scenario~ 

and then goes on to compare and evaluate their relative 

strengths and weaknesses. 

The supporting technical analysis is contained in ten 

chapters. The first seven chapters address the benefits of 

con tro 1, including vehicular emissions (Chapter 1) , nationwide 

and urban emissions (Chapter 2), air quality and exposure 

(Chapter 3), visibility (Chapter 4), carcinogenic.ris~ (Chapter 

5), non-carcinogenic health risk (Chapter 6) and soiling 

(Chapter 7). Two chapters address the cost (Chapter 8) and '.. .. .. ..... . ,..., ~·· ~· , .. , .. ... ,, ' 
5 

last chaoter (Chaoter 10) addresses the sensitivity of the 

technicai results ~o key assumptions made throughout the study 

and includes other, more secondary tvpes of analyses. 

The primary technical ana 1 yses (i.e. , those contained in 

Chaoters 1 throuah 9) will evaluate only the relaxed and base 

control scenarios because these two scenarios are considered 

the most likelv to occur and all technical conceots associated 

with the stringent scenario, such as control technoloqy, are 

also contained in the base scenario. The NOx standards of. the 

main analysis will be 1.5 and 2.3 <;1/mi for LDDVs and LDDTs, 

respe~tively, because they are the current standards and 

certification test data is available under these levels. As 

the methodoloay used in Chapter 1 to adjust particulate 

emissions for different NOx emissions standards is subject to 

some error, this will minimize the use of such adjustments in 

the main analysis. The primary technical analyses (i.e., 

Chapters 2 throuah ·10) also evaluate two diesel sales 

projections: the best and worst estimates. The impact of: 1) 

other LDDV and LDDT NOx standards on the relaxed and base 

particulate control scenarios, 2) the stringent control 

scenario under all NOx standards, and 3) the effect of a no 

qrowth diesel sales projection will be evaluated in Chapter 10, 

Sensitivity. As little firm data is available concerning the 

technolo9y associated with the intermediate sceanario, it will 

also be addressed in t.hapter 10. 
6 

EVALUATION OF CONTROL OPTIONS. 

!. Introduction 

The purpose of this evaluation is to first combine the 

r esu 1 ts of support ihg technical analyses, which addressed in 

detail the costs and environmental effects of controlling 

diesel particulate emissions, and then conduct a comprehensive 

comoarison of the feasible control scenarios in liaht of their 

effect. Three stages are necessary to do this. 

First, the health and welfare effects of the various 

particulate control scenarios will be assessed to identify the 

most siqnificant impacts and to determine the neea for 

control. In addition, this first steo will also identifv the 

kev asoects of the cost and cost ~ffectiveness of d.iesel 

oarticulate control to form a basis for assessinq the deoree of 

control which is reasonahle. This first steo of the analvsis 

will focus on the most likely set of external factors .·for 

liaht-dutv diesels (LDOsl, such as the best estimate diesel 

sales project ions and the ox ides of nitrogen ( NOx) standards 

currentlv mandated bv the Clean Air Act (C.AA) (1.0 aram oer 

mile (q/mi) for light-duty diesel vehicles (LDDVs) and -an 

equivalent stanaard (1.2 a/mi) for lioht-duty diesel trucks 

(LDD'rs)). The imoact of various conceivable sales projections 

for heavv-dutv diesels (i:.:oos) is not sionificant and will not 

be considered in this chapter. 

Second, viable strateoies for controllina diesel 

oarticulate emissions will be identified. While the base, 

relaxed, and strinoent control scenarios are addressed 

throughout t!ie supportinq technical analyses as likely control 

scenarios (see Table 1 for a descriotion of these scenarios), 

the number of such scenarios was l<ept to a :ninimum to retain 

some measure of control over the scooe of the technical 

analysis. Here, the levels of control contained in the three 

orimarv scenarios for the various vehicle groups will be 

combined in various wavs and viable intermediate levels of 

control identified. '1'he relative feasi~ilitv of these 

a 1 t e r n a t iv e cont r o 1 s tr a t e q i e s a long w i th the i r cos t s , i f no t. 

alreadv addressed in the suooortinq technical analvses, •dll 

then be discussed. 

'1'hird, the sianificant features of the various control 

strateaies identified in the second staae will he compared and 

evaluated. 'T'hose strateaies whose disadvantaoes far outweioh 

their advantages will be discarded, leavina only the most 

viahle strateoies for final consideration. The effect of the 

various external factors on LOO control will also be evaluated 

.at this staae. 
LDDV[21 

LOOT [ 31 

HDDV 

7 

Table l 

Description of Control Scenarios 

Analvzed in the Supoorting Technical Analvses[ll 

Relaxed 

Scenario 

Current 

'T'echnologv 

Current 

Technology 

0.6 g/BHP-hr 

Base 

Scenario 

0.2 g/mi 

0.26 a/mi 

0.25 q/BHP-hr 

Stringent 

Scenario 

o.oa g/mi 

0.105 g/mi 

O.l o/BHP-hr 

[ll The availability of emissions averaqinq was assumed 

throughout for LDDVs and LOOTS, while both averaging and 

non-averaqinq situations were examined for HDDVs in the 

suoporting technical analyses. 

[ 2] The three control scenarios for · LDOVs are each evaluated 

under three NOx control scenarios in the supporting 

technical analyses: 1.0 g/mi, 1.5 g/rni, and 2.0 g/mi. 

[3] The three control scenarios for LOOTs are each evaluated 

under three NOx control scenarios in the supporting 

technical analyses: 1.2 g/mi, 1.7 g/mi, and 2.3 g/mi. 
8 

II. Kev Costs and Environmental Effects of Control line Diesel 

Particulate 

A. 9ene,fits 

Chapters 2 th rouqh 7 and 10 of the suopo rt iri<? techn ica 1 

analyses address the environmental impacts associated with 

diesel oarticulate emissions. ~our distinct health or welfare 

effects were address~d: 1) non-cancer health effects, 2) 

carcinoaenic health effects, 3) visibilitv, and 4) soilina. 

These four effects are addressed below. 

·l. ~on-Cancer ~ea 1th Effects 

The assessment in Chapter Ii was not able to make a firm 

findinq with respect to the non-cancer health effects of human 

exoosure to · susoended diesel particulate. Nevertheless, two 

aeneral conclusions were made. First, it is possible that the 

oraanic comoounds ads6rbed onto diesel particulate mav be more 

hazaradous than general suspended particulate matter iess than 

10 micrometers in diameter (PM10), but the available 

scientific evidence was inconclusive on this issue. Second, 

there was some very lir:iited information suagestina that diesel 

particulate may be less hazardous under certain conditions 

(i.e., month breathina) than certain suhfractions of PMlQ• 

Here again, however, no conclusive judgment could be made on 

this point. The overall decision was to treat diesel 

oarticulate like any other type of particulate less than 10 

micrometers in diameter with respect to non-cancer health 

ef'.fects. This decision leads to an ability to use the air 

aualitv and exposure estimates in conjunction with oroiected 

compliance with the National Ambient ~ir Ouality Standards 

('iAP..OS) for ?~10 as an indicator of the i:npact of diesel 

?articulate emissions on non-cancer oublic health. 

'!'able ·2 contains the air aualitv anr.l exposure estimates 

for the various diesel control scenarios under :;est esti'.nate 

sales (and the l.O/l.2 q/mi NO~ standards for LDDVs and 

LDDrr"s). 't'he estimates for these scenarios were developed bv 

applying the ratio of the urban emission estimates of Chapters 

2 and 10 to the air qualitv and exposure estimates of Chapter 

3. 'T'hree indicators of impact are shown: · 1) ambient urban 

concentratinns, 2) microscale concentrations, and 3) annual 

averaae urban exposures. It can reasonably be ar<?ued that the 

mi~roscale imoacts are the least critical. Thev represent verv 

short-term exposures (a few minutes to one hour) and exposures 

of this lenath and at these levels would not be expected to 

cause acute health effects. The remaining two indicators both 

have relative advantaaes and disadvantages. The ambient urban 

concentrations include a wide range of city sizes and 
9 

Table 2 

Indicators of Non-Cancer Health Effect Impacts 

1995 

1980 Relaxed Base Strinaent 

Lead-Rased ~mbient Diesel Particulate Concentrations (ua/m3)* 

<:itv Pooulation 

Great2r than 1,000,000 

soo,000-1,000,000 

2c;o,000-sno,ooo 

100,000-2~0,ooo 

1.2-2.7 3.1-7.4 l.~-3.9 0.9-2.1 

0.8-1.8 2.2-4.9 1.2-2.5 0.7-1.5 

0.9-1.5 2.4-4.1 1.3-2.1 ~.8-1.~ 

0.6-1.6 1.6-4.3 0.7-2.2 0.4-1.3 

Microscale Diesel Particulate Concentrations (uo/m3) 

'R.oadway Tunnel 

Tvpical 57 122 63 3~ 

Severe 145 3oq 160 93 

Street Canyon 

Typical 2 5 2 1 

Severe 14 30 16 q 

On ~xpressway 

"'vo ic a 1 6 13 7 4 

Severe 26 5~ 2A ln 

9eside 'Sxpr~sswav 5 11 n 4 

Annual Averaoe Exposure to U.S. Urban Dwellers (ua;m3) 

Total 2.2 6.0 3.1 l. 8 

* Ra noes are average values plus and minus one standard 

deviation. 
10 

meteoroloqical conditions, hut only re~resent the amhient 

concentration at one or two particular monitor sites in each 

citv. The annual averaqe urban exposures include a wide ranqe 

of -individual activitv oattern effects, but overall are oniv 

based on exoosures in -four U.S. cities. Because the two 

modeling apJ?roaches were shown to be generally consistent in 

Chapter 3 and the exposure estimates are more simole to 

describe, they will receive the primary emphasis here. · 

~s can be seen from Table 2, then, the estimate of annual 

average urban exposure ranges from 1.8 to 6.0 ug/m3 depending 

on the scenario chosen. These are s iqn if ican t levels comoared 

to the levels of the revised NAAOS for PM10 that the Agency 

is currently considering (aooroximately 55 uq/m3). Even 

after post-1983 expenditures of nearly $2 billion (1982 Net 

Present Value), roughly 100-150 areas would still not be in 

attainment of such an NAAOS. ~ rough estimate would be that an 

additional 4 uq/m3 in ambient oarticulate burden would cost 

an additional $44-81 million per year (1982 dollars) in other 

than mobile source attainment costs and result in an additional 

i3-33 non-attainment areas. Thus, the exposure impacts shown 

in rrahle 2 are measurable and arque for further control of 

niesel particulate emissions. 

It is also useful to examine the source of these imoacts. 

Tahle 3 shows the distribution of urban emissions in- 1995 

between four cateqories of diesels: Lnovs, LDDTs, rnedium-dutv 

vehicles/light heavy-duty vehicles (MDV/LnDVs) (i.e., Classes 

!!~-VI) and heavv heavy-duty vehicles (:·H·\DVs) (i.e., r.lasses 

VII-VIII). As can be seen, the two liaht-dutv cateoories 

contribute rouahlv half .the emissi<'rnS under- all the scenarios, 

as do the two heavy-duty ca tegor ie s. Thus, control is needed 

from ~oth qeneral cateqories if the ambient levels and 

?.xoosures described in Table 2 (and the other impacts described 

below) are to be reduced to the furthest decree feasible. 

2. Carcinooenic ~ealth Effects 

The results of the carcinogenic health effects analysis of 

Chapter 5 are shown in Table 4 for the three diesel control 

scenarios. As was done in the previous section, the urban 

emission estimates of Chapters 2 and 10 were used to determine 

the cancer risk estimates for the stringent scenario and the 

other scenarios with s tr ingen t 1 iah t-du ty NOx standards. Due 

to the basic uncertainties inherent in at temot ing to predict 

cancer risk, values in ~able 4 should be reqarded only as best 

estimates of risk relative to other proven carcinoaens. 

Because of limited studies on the human carcinogenic 9otential 

of diesel oarticulate, estimates are based 9ri~arily on results 

of clinical tests performed on animals and lower organisms. 
LDDV 

LDD'I' 

MDV/LHDV 

HHDV 

'!'OTAL 

* Figures 

11 

Table 3 

1995 Urban Diesel 

Particulate Fmissions (~etric tons) 

Scenario 

Relaxed Base 

36,800 (27%)* 19,700 ( 2 7%) 

21,800 (lti%) 11,700 (lti%) 

9,400 (7%) 4,700 (7%) 

61, i:;on (50%) 36,100 ( 50 ~) 

135,600 72,200 

Stri!iaent 

10,700 (26~) 

5,900 (14%) 

2,700 (6%) 

22,i:;oo (:S4%) 

41,900 

in parentheses indicate percent of total. 
12 

Table 4 

Comoarison of Risks from Various Sources 

Sources of Risk 

Commonplace Risks of Oeath 

Motor Vehicle Accident 

Drowning 

Burns, 

Tornados, Floods, Lightning, Tropical Cvclones 

and Hurricane's 

Risks of Cancer Inci~ence 

Diesel Particulate (lq95): 

Relaxed Scenario 

Base Scenario 

Stringent Scenario 

Natural Backaround Radiation (sea level) 

Average Oiaanostic ~edical 

X-Rays in t~e United 

States 

Freouent Airline Passenger 

(4 hours per week 

flying) 

Four Tables?Oons Peanut 

Butter ?er Day (due to 

~resen~~ of aflatoxin) 

Fthylene Dibromide 

One 12-0unce Diet 

Drink Per Day 

Arsenic 

Miami or New Orleans 

Drinkina Water (due 

to presence of 

chloroform) 

Luno r.ancers: 

For Smokers Due to 

Smokina 

For r.eneral Population 

Due to Causes Other 

Than Smoking 

Estimated Annual ~isk 

(risk/oerson-vear) 

222.0 x lo-6 

21;.o x lo-6 

21.0 x lo-6 

2.0 x lo-!; 

1.6 x io-6 - a.4 x lo-6 

o.8 x lo-n - 5.1 x lo-6 

o.5 x io-6 - 3.o x lo-6 

20.0 x io-.:; 

20.0 x io-~ 

lO.n x 10 -Ii 

8.0 x lo-n 

4.2 x io-6 

2.6 x lo-~ 

l. 7 x lo-6 

l. 0 x io-li 

419.o x lo-Ii 

73.9 x io-6 

· Exposed 

Pooulation 

Entire u.s. 

Entire U.S. 

Entire TJ.S. 

Entire U.S. 

Urban U.S. 

Entire U.S. 

Widespread 

Limited 

Fairlv 

i'iidespread 

Widesorean 

Widesoread 

1% of U.S. 

Southern 

u. s. , ~Jr ban 

Entire U.S. 
13 

.~s can be seen, the risk of contracting lung cancer froM 

exoosure to diesel particulate appears small comoared to manv 

of the other risks shown in 'rable · 4. Yet the uo-oer limits of 

the diesel risk estimates under all control scenarios would 

still represent 4-11 percent of all non-smokinq related lunq 

cancer in the U.S. Even the lower limit of risk under the 

relaxed scenario is ahove one out of a million, which has been 

used by requlatory aqencies in the past as a yardstick for 

determininq the need ·to requlate. '1'!'1us, while the estimated 

cancer risk is not tremendous, it is nonetheless measurable and 

suqgests the need for some deqree of control. 

3. Visibilitv Imoacts 

~he visibilitv imoacts of the various diesel control 

scenarios are presented in Table S. The figures were qenerated 

from the results of Chapters 2, 4, and 10 in the same manner as 

the air quality and exoosure estimates of Table !. The 

assu~-ption that visihility i~pact is proportional to emissions 

does not apoly as readily as it ~oes for air auality impact and 

exoosure, ~ut the resultant inaccuracy is insiqnificant for the 

purooses of this report. 

As can be seen, the most strincent control scenario 

provides a 2-16 percent improvement in visibility over the 

least strinqent scenario. While the upper limit of this impact 

is probably perceptible, it is more difficult to tell about the 

lower limit. ~ifferences he tween intermediate control 

strategies would be much less than these absolute effects. ~hus, ~hile the overall imoact of diesel particulate on visi~ility could be characterized as perceptible and deserving 

of control, the chanqe in visihili:y between the individual 

control strateoies is difficult to characterize based only on 

an analvsis of ohysical effects. 

!'-.lo attempt is made in this study to quantify the 

visibility impacts into a dollar value. T!'1is is not meant to i~ply that even a small deqra~ation in ''isi~ilitv due to diesel 

particulate is not economically important. Such ·a benefits 

analvsis simolv is not within the scope of this reoort. 

4. Soilino !moacts 

As ~.,,a s e v id en t f r om th e so i 1 i n c a n a 1 y s i s i n Ch apt e r 7 , little can be said about the ohysical effects of diesel 

particulate on soilinq based on a review of the scientific 

literature. rt is possible, however, that diesel particulate, 

aram- for-aram, mav have a disproportionate effect on soi.ling 

when compared to other types of particulate. Otherwise, little 

information on soilinq is available in the scientific 
14 

~able 5 

Average Peduction in Visibility Due to 

Diesel Particulate in 1995 (oercent) 

Citv Size (oooulation) Relaxed 

More than 1,000,000 24 

soo,000-1,000,000 10 

250,000-500,000 7 

100,000-250,000 5 

Ease 

15 

6 

4 

2 

Strinaent 

9 

4 

2 

1 
15 

literature. Thus, no conclusion can be made concerninq the 

need to control diesel particulate based only on the physical 

effects of soiling. .~ decision on this issue may .be possible 

based on a review of the economic literature, but such a 

benefits analysis is beyond the scope of this report. 

5. Overall Evaluation 

~ number of conclusions can be drawn from the scientific 

analvsis of the four health and welfare effects of diesel 

oarticulate emissions. One, the effect of diesel particulate 

emissions on vis ib i 1 i ty and both care inogen ic and non-ca nee r 

health effects are noteworthy, while the soiling effect is for 

the most part unknown. Two, while these impacts are measurable 

and arque for control, this analysis could not readilv discern 

the level of control at which these effects disappear and where 

control is clearly sufficient. This is particularly true of 

the ca nee r risk impact. Thus, while this analysis shows the 

need for more con tro 1, it cannot alone be used to demonstrate 

when sufficient control has been applied. In the absence of a 

precise cost benefit analysis, such a decision can be made, 

albeit less precisely, by considering the cost and cost 

effectiveness of control. The aroundwork for this is laid in 

the next two sections. 

B. r:osts 

The economic analysis performed in Chapter 8 identified 

three measures of economic impact: 1) trap-oxidizer cost per 

vehicle (coupled with a percentage of vehicles requiring 

traps), 2) diesel sales reductions, and 3) nationwide annual 

costs (or 5-year costs). These three measures are shown in 

~ables 6-8 for the two more stringent control scenarios 

relative to the relaxed scenario. 

Table 6 shows both the cost to the consumer of equipping a 

vehicle with a trap-oxidizer and the oercentaae of vehicles 

reauiring traps. Both the first costs·· (trao-oxidizer system) 

an~ the lifetime costs aooear substantial on an absolute basis, 

while on a relative basis they represent a modest 0.5-2 ~ercent 

increase. Dnder the base scenario, 48-70 percent of each 

vehicle type will experience these costs, while nearly all 

vehicles will be eauipoed with traps under the stringent 

scenario. 

While consumers purchasing diesels will experience a 

l').5-2.0 percent increase in transportation costs, these costs 

will likely reduce the demand for diesel-powered vehicles. 

Table 7 shows estimates of the sales reductions projected under 

the various scenarios. For LDDVs and LDDTs, the impacts are 
16 

Table 6 

'T'otal Cost to Consumers of Ooming and Operatinq 

a Light-Duty Diesel Equipped With a Trap-Oxidizer 

and the Percentaae of Vehicles Reouiring Traos (1983 dollars)* 

Trap-Oxidizer System: 

Maintenance Costs 

~intenance Savings 

Cost of Fuel Economy Penalty 

Total Cost to Consumer: 

Total Cost of ()¥ning and 

Operatinq Vehicle 

Cost Increase Due to 

Trap-Oxidizer 

Vehicles Requiring Traps (%)** 

Base Scenario 

Stringent Scenario 

LDDVs 

$185-213 

$22 

($21-36) 

$33-52 

$219-266 

5il9,418 

1.4-1. 5% 

47.6 

95.l 

$187-211 

$22 

($22-36) 

$41-55 

$229-252 

s~.2 

94.7 

$363 

$22 

($39) 

$126 

$472 

70 

98 

r.RrNs 

$556 

$44 

($61) 

$386 

$925 

70 

98 

rnmvs 

$652 

$44 

($97) 

$917 

$1,516 

$274,911 

0.6% 

7() 

98 

* All costs are discounted to year of vehicle purchase using a HI percent 

discount rate. 

** Presumes the availability of averaging for all vehicle classes and strincent 

1.0/1.2 g/mi !-Ox standards for LDOV's and LDDTs, respectively. Also that -the 

current fleet coITlp)sition is retained in the future. 
17 

Table 7 

Diesel Sales R•ductions* 

1987 1990 1995 

Base Scenario 

LDDV 7.4% 5.4\ 4.8\ LOOT 10.1% 7.9% 6.7% 

·MDV** 3.4% 3.4% 3.4% 

LHDV 1. 5% 1. 5% 1. 5% 

HHDV 0.7\ 0.7% 0.7% 

Strin9ent Scenario 

LDDV 11.1% 7.2% 7.9% 

LDDT 14.7~ 11. 6% 9.7% 

r-<DV 4.8% 4.8% 4.8% 

LHDV 2.2% 2.2% 2.2% 

HHDV 1. 0% 1. 0% 1. 0% 

* Presumes the availability of averaqinq for all vehicle 

classes and stringent NOx standards for LODVs and LOOTS. 

** Estimates for ~nvs, LHDVs, and ~HDVs are based on 

estimated elasticities which are not time dependent. 
18 

substantial: 5-15 percent. qowever, nearly all these lost 

diesel sales should be made up by increased sales of 

gasoline-fueled vehicles. Since all LDOV and LDDT 

manufacturers also produce gasoline-fueled vehicles, none 

should necessarily suffer a siqnificant loss of sales. 

The question arises as to whether these sales reductions 

would force any particular manufacturer out of the LDD market 

entirely. This cannot be answered definitively, given the 

recent volatility of the LDD market. If the diesel penetrates 

the market as projected under the best sales estimate used in 

this report (10 oercent for LDOVs, 30 percent for LOOTs), it is 

doubtful that any manufacturer would be forced out by a 5-15 

percent drop in diesel sales. On the other hand, if diesel 

sales, particularly LDDV sales, did not reach these levels, 

then such reductions could cause some to leave or never enter 

the market. 

'rhe orojected sales reductions for heavy-duty diesels ate 

considerably smaller than those for LDDs, though they are 

probably more crone to error. The a~oroximate loss of one 

oercent for HHDVs is very small. The losses in the other two 

suhclasses (~DVs and LFDVs) are larger, ranaing from about 2-12 

percent. However, in these lighter two subclasses, a sizeable 

portion of the lost diesel sales would '3aain be made uo bv 

sales of gasoline-fueled vehicles and the diesel fr act ion of 

sales within these two subclasses should still increase 

markedly. Thus, in general the HDD sales impacts are probably 

insianificant. 

One caution should be made concernin9 these costs and 

sales imoacts. They presume that the only control technoloqy 

available to reduce particulate emissions is the 

trao-oxidizer. As will be seen in Section III, other 

techniques are available which are less costly, but which 

cannot provide the same deqree of reduction as trap-oxidizers. 

Thus, the cost of standards less str in<;Jent than those of the 

hase scenario may be substantially less than those shown in 

Tables 6 through 7 and may not have associated with them the 

concerns indicated above. Also, the use of these less costly 

technicrues will also reduce the costs and . economic imoacts 

associated with the base and stringent scenarios as well, 

particul3rly the former. This will be considered in greater 

detail in both Sections III and IV. 

c. ~ost ~ffectiveness 

The cost-effectiveness 

two methods for comparing 

controls. Amona mobile 

analysis 

the cost 

sources, 

of Chapter 9 identified 

effectiveness of various 

an urban based cost 
19 

effectiveness appeared adeauate. ~hen both stationary and 

mobile sources are involved, an air auality discounted cost 

effectiveness acpeared to b~ more appropriate, though still not 

entirely adequate. 

'T'he results of the mobile source comparison are shown in 

Tab le 8. As can be seen, except for MDVs, the cost 

effectiveness of all the vehicle classes is very similar under 

both the hase and stringent scenarios. Thus, any preference 

for control based on cost-effectiveness considerations would be 

very small, and, practically speaking, need not be considered. 

One caution should be mentioned. The cost effectiveness 

of both scenarios for LDDVs and LDDTs is very dependent on the 

level of their NOx standards. If higher NOx standards were 

considered (e.g., 1. 5 and 1. 7 a/mi, respectively), the dollar 

per ton figures would nearly double due to the lowerinq of 

engine-out particulate levels. Th is aspect will be considered 

later in Section IV of this chapter as the possibility of 

higher NOx standards are considered. 

The results of the cost-effectiveness comparison between 

stationary sources and mobile sources contained in Chaoter 9 

showed diesel particulate control to be cost effective relative 

to stationary source control when air quality impact was 

considered. qowever, other imoortant parameters, such as the 

ability to focus control in those areas needinq it, could not 

be i~cluded and these could siqnificantly affect the outcome of 

th e an a 1 y s i s • -~ t th i s po in t , then , a 11 th a t sh o u 1 d be s a id i s 

that there is no evidence that diesel oarticulate control 

should be avoided due to the better cost effectiveness of 

stationary source control. 

!II. ~dentification and Assessment of Viable rontrol 0ctions 

The puroose of this sect ion is to review all available 

techniques for controlling d iese 1 part icu late emissions,. 

formulate scecific control ootions, and assess their relative 

technological feasibilities and costs (if not already addressed 

above). ~his will be done in two parts. · 

'!'he first part will review conventional techniques 

av a i 1ab1 e for d i es e 1 oar t i cu 1 ate cont r o 1 ( i • e • , hardware-oriented techniques applied to vehicles nationwide), 

first for light duty and second for heavy duty. Discrete 

levels of control will be identified and their relative 

feasibility and costs discussed. The second part will present 

·a number of more innovative possibilities for HDD particulate 

control, including fuel-related techniques and controls 

oriented toward urban fleets. 
[ l] 

20 

Table 8 

Urban Based Cost-Effectiveness Relative to the 

Re laxe<1 Scenario (19 8 3 dollars per metric ton). fl 1 

Base Scenario Strinqent Scenario 

LDDV 15,400 18,900 

LOOT 16,100 17,300 

MDV 20,000 20,000 

LHDV 11,000 11,000 

qHDV 11,000 11,000 

Presumes averaainq for all classes were applicable and 

strinaent NOx standards for LDDVs and LOOTS. 
21 

The available control techniques for LDDVs and LDDTs are 

discussed together because of the great similarity of their 

engine/vehicle ciesions and their usage patterns .. a.11 of the 

evidence generated over the past 10 years, for both 

gasoline-fueled and diesel-powered vehicles alike, ~as 

demonstrated that LDDVs and LDDTs can meet essentially the same 

emission standards: the· LOOT standards only reauirino a small 

upward adjustment based on their heavier maximum ~eighf. 

The same approach is taken toward HDDs, where trucks and 

buse's of vastly different sizes are grouped together for the 

purpose of discussion. qere again, with the oossible exception 

of trap-oxidizers, the available control technology is 

applicable across the !::loa rd to all J:1DD eng i nes/veh ic le s. ..., i th 

respect to trap-oxidizers, it may be an easier tech no logical 

task to apply these devices to the smaller, lighter HDDs than 

the huge tractor-trailers. However, as indicated in Table 3, 

even including all i:.tDDs up through Class VI in this "lighter" 

grouping affects less than 10 percent of total urban diesel 

emissions. If the control technoloaies a~plicable to these two 

subclasses were more clearly different ar.d the lighter subclass 

had a more substantial emission reduction ootential, then it 

may be desirable to regulate them separately. rtowever, since 

this is not the case under the conventional control actions, 

they are treated tooether below. In the section discussinq 

innovative control options, their potential for seJ?arate 

regulation in examined. 

A. ~onventional 0otions 

1. Light Dutv 

The 09tions available for the control of 

based on hardware-oriented techniques 

straightforward, because the available control 

few in number. Movino from least strinc:ient to 

there are four possibilities. 

LDD oarticulate 

are fairly 

techniques are 

most strinc:ient, 

One, no control beyond that alreadv. aoolied can be 

required (i.e., the relaxed scenario). This approach would 

result in various particulate standards deoencHna on: 1) the 

le"!el of the NOx standard, and 2) whether averaoino is made 

available with such a relaxed standard. Table 9 ?resents the 

corporate average particulate levels for LDDVs and LOOTS under 

strinqent NOx standards (1.0 g/mi and 1.2 q/rni, res?ectively) 

and averaging. While fleet average emissions would be 0.42. and 

0. 52 g/mi, resoectively, the particulate standards would have 

to be higher to accommodate higher than average manufacturers (0.~0 o/mi for LDDVs and 0.56 a/mi for LDO~s). Without 

averaainq, the standards would have to be higher i~ill, as 

shown in-~able 9. 
22 

Table 9 

Individual and Overall Current Cor?orate 

Average Particulate Standard Levels for 

LDOVs and LDOTs Under Option l (orams oer mile)* 

Manufacturer LDOV 

General ~otors .50 

Volkswagen .21 

Nissan .29 

~ercedes-Benz .~O 

Isuzu .22 

Audi· . 26 

Peuaeot .16 

Volvo .41 

Sales-Weiahted .42 

Industry Wide 

Averaqe 

Resultant Averaging 0.60 

Standard 

Resultant Non- 0.63 

Averagina Standard 

Manufacturer LOOT 

Ford .30 

General Motors .56 

Isuzu .13 

Nissan .37 

~itsubishi .43 

Toyota .20 

Volkswagen .32 

Toyo Kogyo .30 

Sales-Weighted .52 

Industry-Wide 

Averaqe 

Resultant Averaging 0.56 

Standard 

Resultant ~on- 0.64 

Averagina Standard 

* Presumes strinqent ~Ox standards of 1.0/l.2 q/mi for LDDVs 

and LDDTs, respectively, and t~e current fleet composition. 

: 
23 

Two, a moderate degree of additional control could be 

obtained via non-trap technology (i.e., between the relaxed and 

hase scenarios) • For example, electronic fuel inject ion and 

sophisticated electronic exhaust gas recirculation (EGR) 

systems (to reduce .negative impact of s tr ingen t NOx. standards) 

appear to be available and able to provide some control. There 

is also the possibility that certain high-emitting engine lines 

may be dropped in this timeframe due to fuel economy and other 

.. __ pressures... ___ O':'_e r al 1, these techn iqu~s could s i.gn if icantly 

reduce particulate emissions from the levels shown in Table 9, 

det?ending on the manufacturer and the desired strinaency. As 

determined in Chapter 10, particulate standards ~nder this 

option would be approximately 0.30 g/mi and 0.35 g/mi for LDDVs 

and LOOTS, respectively. 

· Th r e e , the cu r r en t tr a p- based s tan d a rd s o f 0 • 2 O q / m i and 

0. 26 a/mi for LDDVs and LODTs, respectively, are ;;otential 

candidates (i.e., the base scenario). As indicated above, 

these levels mav be achievable without traps by some or even 

most manufacturers with extensive use of non-trap technoloav, 

even with stringent NOx standards. However, some use of traps 

would be likelv, esoeciallv if the hiaher emittinq General 

Motors Corporation (GM) and Mercedes-Benz models remained in 

production. 

Four, full trap-based standards of 0.08 a/mi and 0.105 

g/mi, respectively, comprise the most stringent option (i.e., 

the strinaent scenario). These standards would require traps 

on essentially all vehicles unless some unforeseen breakthrouah 

occurred in enqine-related technoloav. ~on-trap technology 

would not be as des ir ab le under th is oot ion, from the 

. ·:.<;,r .. :,m~ n l].~ ac;: ~'u.r.:e.,r .. ~~s .,,,,ooJ .. n t .. o .. f ... ,y,~ e.w.., .· .s_j nc ~ . .: . ..v.~.n. , ~ ny.: :·G ~ s ~ .. t.J;:h e .. · q_r e~.t .. i-,·.· lo>i: •• ,._,,",_,,.,;, 

.>.'.::~'"majorit-y--of vehicles:"wou-ld still r·equ·i·r·e· traps;.;:.: .... ;.~.: ... : ..... · .. :.· .. :~.::. .. : .. r.:...-·· .,,: 

~he first option would of course ~e technoloqically 

feasible since no new technology would be required. (The 

NOx/particulate trade-offs used to convert oarticulate levels 

under the current NOx standards to those under the str in9ent 

NOx standards assume only the use of current l=.:GR systems and· 

their associated particulate penalties.) 

The second option would also- be relatively easy to 

demonstrate as beinq feasible. As discussed in Chapter 10, 

sophisticated 'EGR systems are available and are already beina 

applied on a few 1984 vehicles in California to comply with 

their 1.0 a/mi \JOx stanaard. These svstems should be able to 

reduce the particulate penalty associated with the stringent 

NOx standard bv one-half. ~hile the effect of electronic 

. injection is uncertain, it should provide a benefit for the 

h iahest emit t inq enq in es~ at least again improv inq the 
• .... 1 ••• ~f .••• : 

24 

NOx/particulate trade-off. Finally, it appears almost certain 

GM will drop their 5.7-liter engine by 1987 of their own 

accord. (GM has already dropped this engine from its 1984 

California model line and has indicated its intent to 

discontinue this engine Federally beqinning in 1986.) This 

sing-le change would have -a drastic e-ffect on their corporate 

· -- averaae emission level and·· YP:ulo_:_- sianificantly reduce ·the 

number of traps required under this scenario. 

· -~he -third opt ion is -bas ica 11 y-- -an extension of the second, 

t·echno logically.. · · ··However, a-s-- -these ··standards-· would probably 

be lower than that achievable via non-trap technology, the 

likelihood of traps being necessary would be a distinct 

possibility, and would need to be addressed. The record for 

trap-oxidizer feasibility on LDDs, though, is already well 

established. Thus, this option is feasible. 

The fourth option, too, only requires that traps be 

feasible. However, because highly efficient traps would be 

required on nearly all vehicles, some additional leadtime 

beyond 1987 would appear to be necessary. (California is not 

reouiring this level of control until 1989.) However, the 

basic feasibility of these levels does not appear to be in 

question. 

Concerning the costs of these options, the only cost not 

identified in Section II was that of the non-trap technology. 

The cost of electronic fuel injection can be substantial (i.e., 

$100). Fowever, there are other benefits involved besides 

"' ,-: ~'rnfs'~~fon . 'v"'C:On t: r 0 l; ··:·: :.s .. ~'ch;,·;_ - as· ""- ·impr O'leq:· ::'·:'f~_~I· .. ·-e'c-ohomy· -- 'c;i'n·g :-'.':~~:~ - oerforrriance·. ··~ As some - maiiufact·urers'· ~ar'e ·-a1r·ea·ay ·pranning to .. 

anolv this technologv on their enaines, it is evicient that 

these non-emissions related concerns justify most if not all of 

this cost. Thus, this technoloqy should not be costly from the 

point of view of emission control. In addition, the orimary 

cost of a sophisticated EGR system would be the . electroni9 

control unit already included in the cost given above for 

electronic fuel injection. Thus, this technioue should also 

have a modest net cost. Overall, the oortion ·of hardware costs 

associated with emission control should be about $25 per diesel 

vehicle. As such, the urban cost effectiveness for this 

scenario aopears to be very good at about $2,500-$3,500 per 

metric ton. 

2. ~eavv Outv 

The conventional control options available for HODS are 

more complex than those for LODs. This is due to the fact that 

the CAA contains strong mandates for the control of both HOD 

particulate and NOx emissions While the ultimate level of the 
25 

HOD NOx standard is s9ecified in the CAA, the technology is not 

available ·to achieve that level. Thus, the CAA provides that 

EPA ·set stringent interim NOx standards based on criteria 

similar to those specified for the particulate standards. This 

is unlike the light-duty situation, where the NOx standard is 

specified in the CAA. · 

Despite this difference, qenerally speaking there are the 

same four options available for HOD particulate control as were 

identified for LDOs .with· the added complexity resulting from· a 

variable NOx standard. These four options are examined below. 

The first option is again no, or little, further control 

(i.e •. the relaxed .scenario). While current HOD particulate and 

~Ox levels are around 0.7 and 7 grams per brake horsepower-hour 

(g/BHP-hr), respectively, testimony at a public hearing on this 

issue identified 0.6 and 6.0 o/BHP-hr as reasonable, very. 

short-term standards that would require a minimal amount of 

very basic, engine-related control (e.q., injection timing and 

injector design). Thus, it does not appear necessary to 

consider hiqher levels. The 0.6/6.0 q/BHP-hr levels could be 

shifted somewhat toward lower particuiate or lower NOx levels 

if a strong priority existed for one or the other. qowever, 

the 6.0 g/RHP-hr level probably represents the reasonable limit 

for short-term (i.e., 1987-88) NOx control without severely 

impacting particulate levels and, likewise, the particulate 

reduction achievable from raising the NOx standard would not 

justify the increase in NOx emissions. Thus, these levels 

reoresen t the or act ical levels for short-term oar t icula te and 

NOx standards using readily available technology: 

The levels associated with more advanced non-trao HDD ,, .. ;.. ··,·;:-· con,trol .. techr-iology.~:--( ·Le-·. ,: ;· the,,~sec.o:nd.·"'o'ot,ion; "be t 1

wee·n· .,,the -·ba:-se•''': '"'" ., ... ··'""'"· .. ·c: · '-·· ..... "·a ii;d · · {efaxed ~.:: ::~~c:enar io'sT''·.:.a t e· -more .. "(H'ffi'cu ff· 'fo c,··iiio'oi n.t :. th·a-;:r · -"·'~·· ···:::':.~:-: .. ~ . . - those for light duty because less data are available. 

~lectronically controlled fuel injection, aoiabatic enqine 

techniques, and advanced EGR appear to have the most promise. 

(Oxidation catalysts are probably not feasible here due to the 

low exhaust temperatures of HDDs.) An estimate of the max.imum 

effectiveness of these concepts is that they coul~ reduce 

emissions down to particulate and NOx standard levels of 0.4 

and 4.0 q/BHP-hr, respectively, giving equal weiqhting to both 

particulate and NOx control. It is doubtful if more NOx 

control could be obtained even allowinq some· increase in 

particulate levels, due to engine dur ab i 1 i ty and fuel economy 

concerns. t.toweve r, if achieved, such addition a 1 NOx control 

would almost certainly bring with it large increases in 

particulate emissions, well above 0.6 g/BHP-hr. If the ~reater 

weight were given to particulate control, levels around 0.3 

g/BHP-hr would probably be achievable. ~owever, NOx levels 
26 

would almost certainly increase to 5.0-6.0 q/BHP-hr. This 

would mean that NOx emissions would increase 10-20 metric tons 

for every metric ton of particulate reduced. t;iven .the oresent 

acid rain and ozone problems, this does not appear to be a 

desirable trade-ofL Thus, the simultaneous reduction of both 

particulate and ·NOx emissions appears more reasonable than a 

-·-t-r:ade-of-f- of th·e ··cont-rol of one· pollutant for the other·, -a-nd· 

0.4 and 4.0 g/BHP-hr, respectively, will be considered the most 

stringent standard levels associated with the second option. 

·Analogous·· -to · ·the - third - ·LDD- - opt ion (i.e. , the base 

scenario) is the 0.25 g/'BH?-hr stanClard currently proposed for 

HDDs in 1986. As implied in the discussion of non-trao 

technology above, this level, even more than the 1987 LOO 

standards, is dependent on the use of traps. It does not 

appear feasible for rion-trap controls to even approach this 

level. However, with the application of traps, the level of 

the NOx standard becomes more flexible. Traps, in general, are 

sufficiently efficient to provide compliance with the 0.25 

g/BHP-hr standard with engine-out !'articulate levels of ~ven 

1.0 g/BHP-hr. Assuming the availability of averaging, the only 

effect of additional NOx control would be an increased number 

of traps which had to be applied. However, fuel economy and 

durability penalties associated with NOx standards below 4 .O 

g/BHP-hr would still prevent lower NOx standards from being 

pr act ica 1. Thus, 4. 0 g/BHP-hr wi 11 represent the NOx standard 

associated with the trap-based standards as well as the Option 

2 non-trap standard. 

· ·· · .. ·~ '.""':;,. '."·"' ... ~:F:i·n·a;l tv~, ........ fh·eife·- ·b;·:~ .. ·t'h-e'l"'.~ f1.il l) "' i~'t a P"'.'..ba s·ea., ·level'"'·~· ( i~·.-e:~ ~,.-.'the ... ::~·"--·:''."" 

. ·--"-···s·fr'(nqe-nt _, .scen·ario) ~-. ·Assu'mfng·····~: ·startinq···"'.'·~point ·of ·'-0~·6- ·. -

a/BBP-hr, a ?articulate standard of 0.1 a/BμP-hr should be 

attainable with ·high-e.fficiency traps on essentially all 

engines. 'T'he nox standard associated with this opt ion would 

aqain be 4.0 q/BHP-hr, not because of the need for particulate 

c6ntrol, bui because of fuel economy and durability 

considerations. 

The feasibility of the first option, 0.6 ·and 6.0 g/BHP-hr 

for particulate and NOx, respectively, is relatively 

straiqhtforward and achievable by 1987. ~his would represent a 

2-year· delay with respect to the CAA mandate that a 1.7 

g/BHP-hr NOx standard (or an alternate standard representing 

the technologically feasible limit) be implemented by 1985 and 

a 6-yea r delay of the C'".AA mandate that a part icu late standard 

be implemented by 1981. In addition, the 0.6 and 6.0 g/BHP-hr 

standards would not represent true technolo9y-forcing 

standards, as indicated by the Act. However, they .do represent 

the feasible limit given the leadtirne available. Si.nee the 

promulqation of such standards cannot take place prior to early 
27 

1985, the minimum leadtime of 4-years also mandated by the CAA 

would not be available. However, this 4-year leadtime was 

intended by Congress to be associated with a technology-forcing 

standard, which as indicated above, is not the case he re. As 

outlined in the Agency's position when it implemenied the 1984 

HC and CO standards for heavy-duty engines, when the model year 

mandate for imolementina a such standard has been missed, 

implementing the standard at the earliest reasonable date takes 

precedence over the 4-year leadtima ~equirement, provided that 

sufficient leadtime is available, which is the case here. In 

fact, ~anufacturers have had notice of even more stringent 

standards since January of 1981 when the 0.25 g/BHP-hr 

oar t icula te standard was oroposed for the 19 8 6 model vear and ~dvance notice was given ~f a 4.0 g/BHP-hr NOx standa~d for the 

same model year. 

The demonstration of the feasibility of the second option, 

0.4 and 4.0 g/BHP-hr without traps, however, is more difficult 

and would require leadtime in line with the 4-year requirement 

of the C'AA. None of the three control techniques associated 

with this option, electronic fuel injection, electronicallv 

controlled EGR, or adiabatic combustion techniques, have vet to 

be commercialized on HDD engines, though the fir st technique 

will appear on portions of manufacturers 1 fleets as early as 

1986 and on a majority of BDD engines by 1988. However, 

implementation of the other two control techniques is further 

away. "3ecause of durability concerns in the HDD ind us try, it 

is sometimes difficult to require basic engine modifications 

without grantina leadtime for necessary durability evaluation. 

Thus, it would not appear feasible to. reauire the application 

of such techniaues until 1990, which would be the vear for a · ~:·~· .... ,. ·:·::· ·r~ev.i s·e·d: ·~q~·, ·s·~9.pga r~d: .. i'f ... ,t,IJ~ · fJ ~.~ t:·:~:s.t_a;!}.qa;r-a.·::~~l:e.· J:rnpi~m~'nt~'Q· ~::;;~· ··:;-:·~::~·, .. -'\.~. •.· .. ··19sf~·-·.~.fveri' with" this· leadtirii'e·;"' "it ''oil Id not' .. oe· easy to firmly'·" ..... . 

demonstrate at this time the feasibilitv of a 33 oercent 

reduction in both NOx and particulate emissions. ~owever, at 

the same time, it should be difficult for the industry to argue 

their infeasibility given the mandates in the Act, the years of 

leadtime available, and the fact that these concepts have bee~ 

tested on prototype engines and have shown substantial emission 

reduction potential. 

Both the third and fourth ootions depend on the 

feasibility of trap-oxidizers. While the basic feasibility of 

trap-oxidizers for RDDs is not in question, the development of 

HOD trap technology appears to be si9nif icantly behind that for 

LDDs. There appear to be a number of technical reasons for 

this. One, the exhaust characteristics of HDDs make it much 

more difficult to initiate and control regeneration comoared to 

LDDs. HOO exhaust is generally cooler, of much greater volume, 

and both temoerature and volume are subject to wide 
28 

fluctuations due to the more extreme operating conditions seen 

by large trucks relative to those of cars. Two, the extremely 

lona life of HODs also requires a more durable trap system. 

Three, the importance of fuel economy to commercial operators 

mav be a si~nificant impetus to tamoer, since traps_ will cause 

some fuel economy penalty (possibly 1-3 percent) due to 

increased ·backpressure. This last difficulty is ootentially 

the most important, since it is unlikely that the fuel economy 

penalty can ~e- removed-~hrouqh furth~r development. 

There appears to be a regulatory reason, as well, why Hory - -t-rao .. development- --i.S---.behind -that fo.r- LDDs-. Trap-based LOO -

---particulate standar-ds were proposed- in--1979----and- promulgated - in 

1980. These actions communicated a serious regulatory intent 

to the LOO industry and a commitment to the degree of emission 

reduction achievable via trap technoloay. Bven the requlatorv 

relief program of 1981 focused on delay and not relaxation. A 

commitment to reevaluate the need for the standards was made 

(this study is the fulfillment of that commitment), but it was 

never communicated that the study had a prejudged outcome 

(i.e., relaxation). Rather, it was emphasized that the study 

would he highly technical and objective. '!'he result has been 

continuous progress in LOO trap development, even thouqh it has 

been difficult to obtain a clear picture of the manufacturers' 

progress since they have a strong incentive to withhold such 

information. 

In contrast, "SPA did not prooose a trap-based HOD 

9ar t icu late standard until 19 81, and then almost immediate 1 v 

susoended regulatory activitv in. this area for a year and a 

half. After holding a hearing on the proposal in mid-1982, EPA 

·_·'~-~-~.::__: . ·.-:·~: ·~~-~·;annqu~~:~.~~ .. ::t_t. ~:~~~~ .. +a. =_·t~P:~opo_~ .. ~_:. t_h,ec·:p.~' rt i:g_9T·a·t~f.:-:'-s·~~tf¢ra::rsi.~- \i\~t(~ the .. ~· ; ... ::~--~-.'. ' - . . . -·-· ·'oioOos~al ··of'" t'he ·-·Hoo·-Nox ~ sfiindara-~---wh ich is. no·w scheauled --·for-· . -

· Summer of 1984. Thus, the Agency has not conveyed a stronq 

requlatory intent, but rather one of accommodation. 

~s a result, the trao-development programs of the HOD 

manufacturers with one exception, are years behind those of th~ 

LOO manufacturers. For example, two of the five major domestic 

HOD manufacturers have done little trap testing to date, while 

two others are still focused on bench testina. r ... ittle actual 

engine or vehicle testing has been done and the focus of the 

effort is as much to raise problems as to solve them. Only one 

HOD manufacturer is known to have proceeded actively in trap 

development, taking full advantage of available LDD experience. 

Nonetheless, even though EPA proposed a trap-based 

partculate standard in 1981 and Congress mandated strong 

·controls for the 1981 model year, it is clear technologically 

that more time is needed beyond 1987 or even 1988 to implement 
29 

traps on Hoos. Sufficient leadtime is probably available for 

1988 or 1~89, at least until a later date when further pr6gress 

can be assessed. Thus, the standards of either the third or 

fourth options could probably be implemented as early as the 

1989 model year or more certainly for the 1990 model year. The 

statutory framework for the setting of the NOx standard 

requires a revision of the standard every three vears (until 

the 1. 7 a/BHP-hr level is reached) • Thus, if the first opt ion 

were implemented in 1987, 1990 would be the first possible year 

for a ··revised NOx standard and· would also allow a reasonab.te 

amount of leadtime for trap introduction. 

·Concerning cos ts, again as with LDOs, the only cost not 

yet identified is that associated ~ith the non-trap technoloav 

of the second opt ion. Here the cos ts of th is technoloav are 

more difficult to identify than they were in the LDD situation, 

because adiabatic techniques, electronic fuel injection, and 

EGR could involve fundamental chanqes to the engine or fuel 

system and their cost is difficult to identify. Fortunately, 

an answer may lie in the fact that manufacturers are moving 

toward implementing these techniques in the late 1980's or 

early l990's even without impetus from emission standards. 

Thus, their cost attributable to emission control should be 

small, aiven sufficient leadtime, and ~hey should be cost 

effective. 

B. Innovative Control Ootions 

The search for innovative strategies for the control of 

HOD particulate emissions was a result of three factors. One, ~no particulate emissions constitute the major ~ortion of total 

urban diesel particulate emissions. _Two, _.t.+ap§ __ .do not app_ear ..... ·-·· ..... '. ,_ "':•·•.•v••'."''•,.•.·;,.;,. •. ••-~•,..•·.~· ..... -·.,;•t·,7".j. . .',-::--:~1·.·."'\. .... •••..._•'>"·~.l~\ft"-. • ....-<r;""' ......... ,.~,I'•;,.,., •• "'"'"~.,-\,, :!.""'"·•"'~'·"'•"••••~ .• ,.,., '""."'·'' ·.-: ·, .'.:.'••••• •, •·-~··---:::·:--• •·· · .. ~ '","• •. -!::;'''•··" 

'·<.: .:.:; ··-·-~t.9··.1·b~·.:~ ~f:e:a~§.J.91~ ,, .fgr · · HDDs ,. pr~fc>":r" · t.Q~· · 1~9.8\9.-.. and · jeven ·;a·f0ter'' ·:th'a·t'.:''···.:::-:~:>.,,'·:::=::·:;.• 

in-use tampering may be a problem. Three, less than 30 percent 

of all HDD oarticulate is emitted in urban areas, although this 

minority of HDD particulate emissions still represents more 

than half of all urban diesel particulate emissions. The 

logical conclusion is that: 1) major reduct ions in a sizable 

portion of the urban diesel particulate emission inventory will 

not be achievable in the near term, and 2) even in· the long 

term, the traditional strategy of controlling all vehicles sold 

nationwide will, in a sense, be somewhat inefficient. This led 

to a search for strategies for controlling HOD particulate emiss~ons specifically in urban areas only. · 

Two strategies appear to have merit. One would 

selectively regulate those types of HDDVs which are heavily 

urban-oriented (an urban vehicle 09t ion) , a poly ing lesser 

control to those which are rural-oriented. The other would 

selectively regulate urban flee ts (an urban fleet opt ion) : it 

being easier to monitor maintenance with fleets and fuel 

modification becoming a possibility due to their · captive 

fueling capability. 
30 

The selective regulation of. urban-oriented HDDVs would 

require the differentiation of vehicle types based on objective 

criteria that would not be easily modifiable (i..e., weight, 

number of axles, length, general description of load carrying 

portion, etc.·). Two or three vehicle types come to mind as 

heavily urban oriented: transit buses, garbage trucks, and 

cement mixers. An analy~is of their use nationwide shows that,. 

if one--assumed their use was entirely urban, then their vehicle 

miles travelled (VMT) would represent rouahlv 20 oercent of all . · HDD ur!:ian VMT, with transit buses_ .. representing slightly more 

.. than half of this .figure. 't the same time, the great majority 

of the remaining HDD VMT nationwide is associated with very 

general types of vehicles, such as panel trucks and flatbeds, 

which would definitely be used in both urban and rural areas. 

To a f feet these vehicles, weight classes could be used. One 

option would be to include all HDDs in Class VI or below. Such 

vehicles would be expected to ~xpend rouqhly half of their VMT 

in urban areas, so their control would be as cost effective 

from an urban/rural point of view as that of LDDs. Their 

inclusion would increase the percenta9e of affected HDD urban 

VMT bv 20-30 percent, to a total of 40-50 ?ercent. · 

In addition, there are certain cities where bus usage 

alone represents a sizeable majority of HDD VMT. For example, 

bus VMT represented roughly 60 percent of all 1980 HDD VMT in 

New York City and Chicago. (In contrast, the same figure for 

Los Anoeles was 4 percent.) However, the dieselization of the 

smaller HDV classes will reduce these fractions in future 

vears. Aoain for example, bus VMT is projected to represent 33 ... · -··~,.~~--~:nd·r--"4:2:.·oe-rce·nt··-··of .-200·0· ~oo-::·V·MT·-..:i·n. New York·· Citv ·and ~Chicago·.;,'·.···c:·:-: .. . ~-~r:; ': .;.,:. ·._;r ·:.:; r'"e'.."s p~c t:'fv-el ~(; ~-:.a:o. -'ffec"ie as~ -0 f'.: '6 h e'::·cht:r"'a·.-: to .: o'fre ::."h·a'i-"f .... f r:::o'm·· ,:.·2 lrr:--r e'n't .·c1 eve ls, 1'ut still sianificant fractions. An additional reason 

to focus additional control on tr ans it buses is the fact that 

they are publicly opera.ted and are heavily subsidized by the 

Federal government. It would appear to be particularly 

aporopr ia te for these buses, •.,rh ich serve the public in te rest, 

to demonstrate the ability of technology to control the very 

aooarent oarticulate emissions of diesel enoines. Thus, there 

is some potential for a large degree of additional control in 

particular cities, and for a significant degree of control in 

other cities via an urban vehicle option, as well as a certain 

approoriateness to focus control ori transit buses. 

The second strategy, instead of identifying vehicles by 

functional desiqn, focuses on user type and location (i.e., 

urban commerical and public fleets). This strategy has . the 

advantaqe of affecting nearly all urban-oriented diesels. The 

difficulty arises in defining an urban fleet and enforcing the 

requirement. A fleet may be located in an urban area but 

involve almost entir~ly over-the-road operation (e.g., most 
31 

tractor-trailer fleets are located in suburbs). Thus, weight 

limitations or other means of distinguishing certain trucks may 

need to be added to address this problem. .~lso, there is a 

reliance on the HDD purchaser buying the proper vehicle from 

the ~ealer. Since most dealers sell to both urban and 

non-urban users, deception or conscious manipulation would be a 

definite possihilitv. finallv, this strategy could create 

enough incentive to cause-a firm to relocate. 

Despite these problems, this strateqv should have the 

ability to address the_ large .. major_i_ty of urban HOD emissions. 

While figures are not readily available on the relative mileaoe 

of fleets versus total vehicle usage, the three vehicle tvoes 

mentioned above for the first strategy would definitely. -be 

included plus even larger utility, city, and delhrery fleets. ~hus, a sizeable majority of urban HDDs should be affected. 

Both of these urban strategies would also have a second· 

acvantaoe over the conventional nationwide control approach. 

While selective regulation could be oriented toward requiring 

:nore stringent emission controls to be cart of the enqine or 

vehicle, it could also be oriented toward requiring a cleaner 

fuel to be used, since urban fleets usually have their own 

fueling facilities. Gasoline, for example, would certainly be 

cleaner with respect to particulate emissions. ~owever, a 

large fuel economy penalty would be involved and emissions of 

lead would increase, at least until these vehicles are equipped 

with catalvsts. A better alternative would aooear to be 

methanol. -Methanol engines have little or no--particulate 

.......... ~.!TI is~ ~~n s, ._ .. lp"w .. NO~ 0 .. ero,,t?.? ip n~ 0 -,.qn_g ;, ~.~,l'.\ .. ha,ve •·: f.u.e 1 .. e f f..ic.i e.nci:es. "'·· :-.:· · · -"· 

::.- ....... ·aop~_oachinq ... those· .·.·of··.· ·the ; diesel •... -'And, while methanol ';'i-§-.·';"·~~-.:: r.:: 

currently not available at service stations, it is readily 

available in bulk quantities and could easily be bought and 

used by fleets with their own facilities. 

Enqine manufacturers could certainly produce a methanol 

engine if there was a market for them. A German manufacturer~ 

!1.1. ~. N. , already has a product ion- ready me th a no 1- fueled cHe sel 

engine and Detroit Diesel has recently developed a 

methanol-fueled d iese 1 bus enq ine under con tr act to the 

California Energy Commission for fleet testing in San 

Francisco. r,iven the current and projected future olut in the 

methanol market (100,000 to 200,000 barrels per day), fuel 

supply should also not be a problem. Roughly 67,000 barrels a 

day of methanol would be required to fuel every transit bus in 

the U.S. 5ince conversion to methanol would only occur through 

the purchase of new buses, it would take a number of years for 

even half of the bus fleet to convert and the present methanol 

supply should be more than sufficient. 
32 

The question is simnlv one of cost, primarily of the 

fuel. A methanol engine should cost approximately the same as 

a diesel, and its fuel efficiency should also be roughly the 

same. However, methanol is likely to be more expensive on an 

enerqy and mi le age bas is. Overall, then, a switch to methanol 

would likely increase operating costs, at least as compared to 

current petroleum prices. 

·~- ·To-·-estimate th-is· cost:-,---estimates of the prices cff both 

diesel fuel and methanol are needed. No. 1 diesel fuel 

currently costs roughly $0.90 per gallon delivered to a transit ___ _ 

- autnority, without tax-~ Methanol is currently _available for 

$0;4·5:..o.so-per--gallon.on the gulf coast. Both of these prices 

are depressed because of the depressed worldwide economy, but 

methanol the more so, its price being 30-35 percent below that 

of two years ago. Even though a methanol production surplus is 

projected through the rest of this decade, it should not be as 

severe as the current situation and the price will likely 

increase in terms of 19 8 3 dol lares. lJue to the uncertainty in 

the degree of this increase, a range of $0.50-0.70 per gallon, 

includinq bulk distributlon, will be used. 

Transit buses obtain a fuel economy of about 5 miles oer 

qallon on No. l diesel fuel. Since methanol contains only 44.5 

percent of the energy per gallon of No. l ~iesel fuel, the fuel 

economy of a methanol-fueled bus would only be 2. 2 miles per 

gallon. Assuming the relative fuel prices remain steady in the 

future, the fuel costs of a diesel bus would be rouohly $0 .18 

per mile and that of a methanol hus would be $0.22-$0.31 per 

mile, or 25-75 percent higher. At 30,000 :niles per year, this 

translates into - - an- .. -annual~.-.,--c.ost.~"'" of _.usina -.. methanol· . of __ "",,;: .. -~ .. :.;«· ~' .'$1\ ·iob ~:$-3~:9·o-Q.:;.~.~:e·i:·'.' ye a;(~;,:: o t' :-~:a -. ~e-t i·~ pr e:s·e~ t' ~ -rJaTd~ ·: '1A-f·e time:: ·"c·o s"t .>:';'J ~ 

(15 years) of $9,100-$29,700 in the year of vehicle purchase. 

With fuel costs being 8 percent of overall costs, a switch to 

methanol would increase the overall cost of operating a bus by 

2-6 percent. 

fiowever, it is important to consider that a 

methanol-fueled bus engine would meet any particulate and NOx 

standards conceivable f.or diesel engines without any additional 

hardware or adjustments. Thus, the cost of bringing a diesel 

enaine to these levels must be considered. For particulate 

control, a trap would· certainly be necessary at a cost of 

$600-700 initially, and a 2-percent fuel economy penalty. For 

NOx control, severe timing retard or an exhaust gas 

recirculation svstem would be needed, costinq $0-200 initially 

and a 5-10 percent fue 1 economy penalty, and yet st i 11 not ~chieve the level of the methanol engine. Overall, these 

control costs would increase the overall costs of owning and 

operating a diesel hus hy $460-770 per year, or $3, 500-5, 800 
33 

over the 'life of the bus (net present value in year of vehicle 

purchase). Thus, it would appear that the methanol option 

would still be more costly, though it should be more easily 

achievable technica~ly and provide greater NOx contr~l. 

One final point bears heavily on the relative economics of 

using methanol versus diesel fuel. If the price of diesel fuel 

rises more rapidly in t!ie future than that of methanol, which 

is possible, at some point methanol will be less costly to 

use. ~owever, predictinq future petroleum prices is beyond the 

scope of this study. 

One method to at least partially avoid the issue of cost 

would be to implement a particulate standard for urban vehicles 

which could be met with either trap-oxidizer technology or 

methanol. Methanol engines could easily be feasible by or even 

before the feasibilitv of traps. Thus, enqine/vehicle 

manufacturers would have a choice as to how to meet the 

standards, via traps or methanol, and the overall approach 

would involve less risk than if either one were the only 

potential option. Even if traps are eventually used, this 

strategy would be 3 to 4 times as cost effective as a 

nationwide trap-based strategy. 

Of the two options, the urban-vehicle (buses, garbage 

trucks, cement mixers) strategy appears to be preferable, 

primarily because it avoids the implementation and enforcement 

problems of the urban-fleet strategy·. The cost issue still 

needs to be ad~ressed in further deoth. However, the ootential 

for sionif icant, cost-effective emission reduct lens is presen~.- For example, either trap technology o~ methanol could ·.-.· -.. -·- pr-ovi'c~:e~. ·c~mpl'i-ance··- wi~l! ·a·o,~2s · g/J3·HP-~r. st:a·na_q.~.r;a·. -~":~at'i:onw_idi:U'''r::,ri:·. ~· .. · a·ssum'ing such····engfni?°ii» just'. comply with "·t:n·§ '0.25 .q/BHP~·h"-[-..... ,.; ·-

standard, t!iis strategy could reduce 1995 HOD urban emissions 

from 55,000 metric tons per year to 41,000 metric tons per 

year, or by about 20 percent, compared to a 0.40 g/BHP-hr 

standard for all HDDs. Even oreater reductions would be 

achieved if methanol engines were chosen as the compliance 

strategy, since these enqines should emit well below 0.25 

q/BRP-hr particulate. Thus, this approach merits further 

consideration. 

tV. Discussion of Control Ootions 

The previous section laid out the available control 

options for both LOOS and HDOs, including two innovative 

control s tra teq ies for ~DDs. In th is sect ion, these opt ions 

will be compared and evaluated and, where possible, conclusions 

drawn. As in the previous section, LOO control options will be 

discussed first, followed by those for HDDs, as the analyses in 

each area are for the most part independent. 
~ ~ ·-....... - -. 

-. -,.. 

• • .- -· ...:·. !l" 

34 

A. Lioht Outv 

The summary of environmental impacts in Section II 

demonstrated a need for further control beyond the relaxed 

scenario. It also showed that LOOs were roughly half the 

problem (i.e., contributed half of the emissions). A need to 

control LOO emissi ~s beyond curr~nt levels was evident.-

The analysis .n Section II identified - of control beyond current emission levels: 

LDOV standards, 0.25-0.3 g/mL 0.2 g/mi, 

three stannards are demonstrably feasible, 

level would probably require some time 

implementation, even with the availability 

three further levels 

speaking in terms of 

and 0~08 q/mi. All 

thouoh the· O. 08 q/mi 

beyond 1987 before 

of averaginq. 

At the same time, the summary of costs in Section II 

showed ootentiallv significant economic impacts for the 

trao-hased standards if the trap-oxidizer were the onlv control 

technique employed. While both the initial and lifetime cost 

impacts are only about 2 percent of vehicle purchase cost . and 

total lifetime cost, this small impact ::an have a sizeable 

effect on sales of a consumer alternati·1e like LDDs, since 

their desirability is very sensitive to small relative economic 

changes. As was seen, equipping all vehicles with traps could 

reduce LOD sales by 7-15 percent. ~his is a sizeable reduction 

even considering the fact that most of these lost sales would 

be made up by sales of gasoline-fueled engines. 

Tab le 10 . summarizes the urban emissions, _various_ cp~.!;~ _ .. '"~l.J;~~'o~ni~"~ ;.·Qn, ~~'-.3~tf-c3;> "~'ui oa,n -~~co~ t~- ~e f.{e.c t:i:v;e:n:e:5~5·~_·.:.{or . -·'th:e ... f OU r - -·TJ-00 ·-~ ~­

control options. The values presented in this ta~le differ 

somewhat . f ram those shown in Sect ion I I pr ima r i 1 v because the 

voluntary elimination of GM's 5.7-liter diesel engine is 

assumed here. Urban emissions are shown in Table 10 as an 

indicator of environmental effects since all of the health and 

welfare impacts discussed in Section II are essentially 

proportional to urban emissions. 

As can be seen, there is a fairly steady and consistent 

change in emissions f ram opt ion- to-opt ion. The cost and sales 

impacts trends are also reasonably steady. 'l'he second o;:ition 

should - have a fairly low cost due to the other benefits 

associated with the use of electronics (e.q., improved fuel 

economy, electronic capabilitv for peripherals, etc.). For 

ootion 3 and 4, the use of traos is more costlv and hence, more 

liable to affect sales (Options 3 and 4). These affects are 

more pronounced under the fourth action. Manufacturers would 

definitely use traps on nearly all vehicles because the 

sizeable reductions reauired could not even be approached with 

non-trap technology. 
35 

Table 10 

SLIJTmarv of Sianif icant Information for the LOO Control Octions* 

UXN/f_ror 1995 Average Incremental 

Standard Urban LDOVs/LD[YI's Lifetirre Cost Sales Urban Cost 

Options Emissions Requiring Per Vehicle Impact Effectiveness 

(a/mi) (m. tons) Traos (%) (1983 $) {%) ($/m. ton) 

1. 0.6/0.56 58,600 0 0 0 

(0%) [**1 

2. 0~3/0.35 43,400 3-7 15-30 0-1 2,500-3,500 . - (30%) - .... ·- ' . 

3. ().2/0.26*** 31,400 43 55-85 1-5 8,600- (46%) $11,000 

4. 0. 08/0.105 16,600 100 $220-270 7-15 $15,000- (72%) 17,000 

* values assl..IIT'e elL~ination of GM 5.7-liter diesel LOO/. 

** Incremental oercent reeuction from total 1995 urban emissions for LDDs under the 

relaxed scenario. · 

*** For comparison, Ootion 3 with 1.5/1.7 LOO~ standards 1NOuld be 1995 urban emissions 

of: 1) 30,fiOO metric tons1 2) a 9 percent of LDDs requirinq traos1 3) averaoe 

lifetime costs of $20-$45 per vehicle: 4) a 1-3 percent impact on sales: and 5) an 

urban cost effectiveness of $2,500-$3,000 per metric ton • 

••• ! . •. • • .• . ~ •. , . -;· ' -~~· • ..: •• •' ·'.:~ .... ~ ~.' :.:;·.~-.: . :,;:--'~ ._. .:.···:·: . :~·-~· ·• ··:~;:-... :· .. 't. ··:-·· :;-::~. ;· •. ..... ·:. ?"_ '~ .. : ... ·_::·::·.t:: ~~.~j';:. _;:-:-, . . . ... . • ... • . :' •• ·.~ . • 41. •• • .. . :"' .... ~: : .. :· .. ' -·· -~ ·· . .:.. 

-~~-- ::··.t.: •• ~-· .. 5.n. •. ~·: ::.~ ··~~: ;-it"::, . .;._--~;:;~ ':'r:·:r:,:;;~~-.-::~Fr- /'l,ol ,. ... ,. ~;· .,..:·t:.:·.t·,;.. i;: .. ' ~· •· :.-:-~- ·:-- • "::. ~·:·.+-. ,. ·~-·· •.• · ... ·< ~·::· ..:_.- -c-.:·-:.::·~. .. ' ..... .. ,. ..~ ... ' : " ! ... 

} " ~··,... 

. . 

. 

. f~~ .. ~-~ ·~ 

•• 

-

~ 
36 

Given that further control is needed from LOOs and that 

control down to the levels associated with the. second or 

possibly third option appear to be quite feasible and 

relatively inexpensive, control to this level appears 

reasonable. qowever, given the low level of urban emissions 

under the Option 3 standards and the sizeable costs (direct and 

indirect) -- a-ss-<:rc-i-ated with Option 4, it· does not appear 

reasonable to consider the full trap-based standards at this 

time for LOOs. ~owever, in the lonq term, the Ootion 4 

standards-~a~ be a reaso~aSle control strategy, particuiarly if 

LOO sales increase well beyond current projections. .a.lso, the 

issue of requiring traps on nearly all LOO models will be much 

clearer in a few years, technologically and economically. '1'he 

question, then, is whether to implement the Option 2 or the 

Ootion 3 ton standaras. 

a.t issue technically is only the number of traps which 

would be required, since at least one manufacturer is likely to 

require traps under either option. Standards of 0.3/0.35 g/mi 

for LDDVs and LODTs, respectively, would probably eliminate the 

need for traos for all but one manufacturer. Standards of 

0.2/0.26 g/mi would likely require several manufacturers to 

applv traps on at least some of their vehicles, unless major 

engine modifications were employed. However, the majority of 

the incremental urban emission reduction of Option 3, 12,000 

metric tons per year in 1995, would not come from the use of 

trap-oxidizers, l)ut from non-trap techniques and, thus, should 

be more cost effective than t~e sole use of traps. This 

i::icrernental- emission- reduction· is - near-lv 10 -oercent of .1995 .. --. .'· 

urban erniss·ions ilnder the relaxed ·scenar"'io· and: is 'larger than·~" 

total 1995 urban emissions from ~DVs and LHDVs combined. a.t 

the same time, Option 3 would require the development of trap 

technology by most manufacturers for application on only a 

minority of their fleet. Thus, based on cos ts and emission 

reductions, there are pros and cons to either Ootion 2 or 

Opt ion 3 and either opt.ion could be justified and irnplemen tea· 

via rulemaking (though retention of the Ootion 3 standards 

would of course not require any action on .the part of the 

Aqency). ~owever, there are a couple· of additional factors 

which should be considered. 

There are two external factors that could affect the LOO 

situation: the level of the LOO NOx standards and the level of 

LDD sales. Considerinq the effect of NOx standards first, the 

alternatives to the 1.0/l.2 g/mi standards discussed above are 

.all nurner ically higher: l. 5/1. 7 q/mi and 2. 0/2. 3 g/mi. 

Chaoter 10 showed that the effect on particulate emissions of 

mov ina from 1. 0/1. 2 g/m i to 1. 5/1. 7 g/m i was much la rqe r than 

the second step to 2.0/'2.3 g/mi. Thus, the discussion here 

will emphasize the 1.5/1.7 g/mi option. 
37 

~able 11 deoicts manufacturers' coroorate emission 

averaqes under the more relaxed 1.5/1.7 q/mi standards. ~s can 

be se~n, the qreat majority of both LDDV. and LDDT manufacturers 

are already well within the range of the Option 2 standards, 

even without consiaerinq the application of additional non-trao 

technology. This reduction in engine-out particula~e emission; 

across the board has the effect of reducina the number of traps 

required at. any standard level. Por Option 2, trap usac:ie was 

shown in Chapter 10 to· drop from three to seven percent to 

about one to three percent, thereby reducinq the cost and 

imorovinq the cost effectiveness of attaininq the essentiallv no~-trap· standaros. At the __ s~_m~ J:ime, t-he reduction i~ 

enqin·e-out _particulate emJssions .. ~~9u9~s .the emission reduction 

associated with olacina a trap on any inrlividual vehicle. This 

causes the cost effectiveness of aoplyinq trac-oxidizers to 

worsen bv rouchly a factor of two under Option 3 compared to 

that under strinaent NOx standards. Thus, the desirability of 

requiring traps siqnificantly lessens. In qeneral, stringent 

non-trap standarcs shoul~ he i~plemented under the 1.5/l.7 g/mi 

NOx option. This would mean particulate standards in the range 

of n.2 q/mi for LDDVs anrl n.3 a/mi for LDOTs. 

Under 2.0/2.3 g/mi NOx standards, the same arc::rnments are 

si'.Ttply carried a step further. l?articula':~ levels are reduced 

even further than those indicated in Table 11, making even 

stringent Ootion 2 standards achievabl~ by nearly every 

manufacturer without any additional control, trap or non-trap. 

Opt ion 3 standa ra s should be achievable hv nearly a 11 

manufacturers with non-trap technolocy. At the same time, the 

cost effectieveness of applying traos worsens even further. 

Here aoain, the choice should be to imolement stringent 

-· .n0.n-:J: r .. ? .. F! ... s.t? n/L~ rd.!?~'"' ... , 1 D. ·. try i § _ ,~.as.~.'-- :~.!:t.i.s .. .wo~-1:::'.L- c:me an- .P.a·,r:~~Jc_l,l·.'.l-a t.e. . ·-~-:-·: .· , .... _ .. -:·. ~-~. s t«:fn··ci-~ r-·d;~r 's:1 tent ly· :be rcw-- o-~ 2·- g/m·i ····~rna----n·;'.3.:::q /m i'·i'" .. r" e·spec·t ive l~(. ~::!~ :•:-,"..r.:>·,•:.·n~· " 

ronc~rninq _the LDD sales effect, ~ither of two 

oossibilities could occur: 1) sales could he substantially 

low~r than projected by the best es.timate, or 2) sales could he 

substantially higher than projected by the best estimate. If 

sales did not increase bevond their current levels, the overall 

need for LDD control would lessen, but not be eliminated since 

future LDD particulate emission inventories would continue to 

qr ow beyond today's levels as shown in Chapter 10. 

Furthermore, the ~vailable technolocv, cost oer. vehicle, and 

cost .effectiveness of control would all remain roughly the 

same, since thev are unaffected bv sales. 'T'hus, overall, the 

need for the additional control ·provided hy Option 3 would 

lessen. 
38 

Table 11 

Current Individual and Overall Corporate Aver~ge 

Particulate Stanoard Levels for LDDVs and LDDTs Under Option 1 

Presuming NOx Standards of 1.5 g/mi and 1.7 g/mi, Respectively 

(orams oer mile) 

-Manu-facturer 

General Motors -- vo11«swaa-en -

~issan 

Merceces-Benz 

Isuzu 

Audi 

Peuaeot 

Volvo 

Sales-Weighted 

Industry Wide 

Average 

LDDV 

.16* 

.·2 0 

.26 

.42 

.20 

.20 

.26 

.?9 

.20 

Resultant Averaqinq 0.42 

Standard 

Resultant Non- 0.43 

Averaginq Standard 

Manufacturer 

Ford 

-Genera1 '1otors 

Isuzu 

Nissan 

Mitsubishi 

Toyota 

Volkswagen 

Toyo Kogvo 

Sales-Weighted 

Industrv-Wide 

Average 

LDD'1' 

.29 

• 3 4 

.25 

. 3 ~ 

.39 

.19 

.31 

.29 

.33 

Resultant ~veraqina 0.39 

Standard 

Resultant ~on- 0.39 

Averaaing Standard 
39 

If sales are hiqher than projected, there is no douht that 

the Option 3 standards would be appropriate. As noted in 

Chapter 2, under worst case sales, 1995 LOO emissions under the 

Option 3 standards (base scenario) are still at least 40 

percent above those shown in Table 11 for the Option 2 

standards under best estimate sales indicating the need for the 

additional control provided bv Option 3. 

It is conceivable that the level of the LOO standards 

could be directly tied to the level of LOO sales, if it were 

decided to relax the existing Option 3 standards to those of 

Option 2 at this time. Ideally, the sales or sales fraction·· --- limit would be .on a fleet-wide basis, since it is the 

fleet-wide diesel penetration that affects emissions. However, 

in this case, most manufacturers could find the level of the 

standard changing due to the actions of one or two other 

manufacturers who decided to invest heavily in diesels. While 

the more stringent standard itself would be equitable, since it 

would be the same for all manufacturers, the latter 

manufacturer (s) would have more advance notice of the switch 

since it is fully aware of its own future product plans. 

There would also be little incentive to keep LOO sales low 

since the level of the standard would only be indirectly 

connected. 

To mitigate this problem, sufficient leadtime would have 

to be given between the time diesel sales exceeded the limit 

and the time the revised standard was imposed. While the 

effort and time. needed to reimplement the Option 3 standards 

would be avoided, this does not appear sufficient to offset the · :·· '· · -·~·: p.~::o,bl,en1 :'tti-.it. ,_a~ .91ve·n fita-niif a.c,f,u~re.r~: .~w·c,-u:,t~l:. ·not. ,ha.v·e · d'i'rect ._. cpn.fr:.g:i~.::.:: -~~;::-····::~~·::~ .. ·-' . over"" "'whether·" 6r" not it' 'h'ad". fo' me'et . th'e" more . stringent ..... _, . -

oarticulate standard. Direct control would be critical to anv 

sales-based approach since it provides the incentive to keep 

diesel sales low, as currently predicted by the manufacturers. 

The other alternative would be to apply a diesel sales_ 

limit to each manufacturer. This would eliminate the need for 

leadtime since a manufacturer has control over its own sales. 

A problem arises, however, in how to equitably set the sales 

limit. 

Limits based on absolute diesel sales are probably 

unacceptable. The wide range of total sales volumes among 

manufacturers would make this type of limit very inequitable. 

A single diesel sales fraction limit is also not likely to 

·be acceptable, since LOO manufacturers currently sell between l 

and 70 percent diesels. A limit near the upper end of this 

ranqe would allow an enormous increase in fleet-wide diesel 
40 

sales before most manufacturers would exceed their limit. A 

limit near the lower end of this range would immediately impose 

the more strinaent standards on a number of manufacturers and 

issues of equity would quickly be raised. This very issue was 

raised in-1979 when r.M proposed an emissions averagina approach 

_t:))at_ i_n_cluded both 9asoline and diesel vehicles. '!'his approach 

resulted in increasinaly more stringent diesel particulate 

standards as a manufacturer's diesel sales fraction- increased --a-nd was immediatelv-- cha-1-lenged by Volkswaaen and Mercedes-9en-z, - -. ma n-u fa c-t.u r e r s - w i th. h i g h d i e s e 1 s a le s fr a c t ions • 

A ciiesel sales fraction limit that varied between 

manufacturers would appear to avoid this problem. However, the 

question of how. to set each manufacturer's limit arises. One 

approach that appears to minimize inequities between 

manufacturers would be to set each manufacturer's limit at its 

maximum diesel sales fraction in recent years plus some margin 

for moderate growth. Specifically, the model years 1978-82 

should include all manufacturers peak diesel fractions and an 

absolute cushion of 5 oercent* should provide f.or both adeauate 

diesel growth based on manufacturers' current statements and 

adequate protection for the environment since LOO sales would 

·be held to less than 10 percent of total light-duty sales. ~ny 

ma nu f ac tu re r desiring to produce more di i: sels would have to 

comply with the existing Option 3 standards, which would be 

reasonable since manufacturers are currently requesting the _ .~elaxation of these standards due to their low projected d~e~el 

sales. . .:,._ ~ .... · 1 -. -·- - .;,. -- ... _ :... -- . .: .. -· - ._...... . ...:. -· .,. ..... · -- ·- ... .,---·· -·:1:n··-·su-mm~iry; -the~---oros- and con"s. "0"f "r·e.tai"r\i""na ··-th·e--current 

Ontion 3 standards versus relaxing them to the Option 2 

standards are rouqhlv balanced. !f Ootion 3 were chosen, then 

no act ion would have to be taken by the Agency. If Opt ion 2 

were chosen, it may be appropriate to tie the relaxation to LDD 

sales levels since manufacturers are currently basing thei~ 

arauments for relaxation on verv low LOO sales. !n this case, 

the best approach appears to be relax the LOO particulate 

standards to those bf Ootion 2 on a manufacturer-specific basis 

(al 1 should initially experience the re lax at ion) as long as 

that manufacturer maintains its LOO sales fraction at or below 

its historic (1978-82) peak plus 5.0 percent. Otherwise, it 

aopears appropriate to retain the current Option 3 standards, 

as it appears inappropriate to grant a permanent relaxation on 

such volatile grounds as projected LDD penetration. 

* For example, if manufacturers A and B have peak LDD sales 

fr act ions of 5 and 50 percent, respectively, their limits 

would be 10 and 55 percent, respectively. 
·"' .... 

41 

B. Heavv Dutv 

The environmental impacts summarized in Section II also 

demonstrated the need to control HDD emissions beyond the 0.6 

g/SHP-hr level. However, unlike the options for further 

control for LDDs, all three levels of additional control for 

HDDs could not be implemented in 1987 •.. This occurs because: 

1) engine modifications need to be extensively tested for 

durability due to market demands, and 2) the application of 

traps on HDDs is more difficult than that on LDDs. Thus, the 

technology-forcing mandate of Section 202(a) (3) (A) (iii) of the 

Act notwithstanding, the only option truly viable for HDDs 

prior to 1990 is the first option. 

This first option, 0.6/6.0 g/BHP-hr for particulate and 

NOx, respectively, is achievable as early as 1987. This level 

is supported by at least one manufacturer's comments to the 

proposed 1986 HOD ?articulate standard as well as bv an 

analysis of current ROD emission levels and projections of 

minor control techniques applicable in this timeframe. 

Given the 3-year standard revision cycle provided by· the 

CAA, the earliest year for a revised set ~: standards would be 

1990. F1ere, Options 2, 3, or 4 are potentially available. 

Given the demonstrated need to control RDD emissions and the 

apparent cost effectiveness of the second option, control to at 

least this level appears reasonable. The only questions 

associated with Option 2 are the actual feasible levels of the 

standards. Standards of 0.4 and 4.0 g/BHP-hr for particulate 

and NOx, respectively, probably represent the maximum degree of 

contr9l ac~_ieyab.le __ pv. 19~0 .. '1ithot.t.t. traps ...... Th.us .. , p.romulg_?-Jion ... . of .. _ these· ... sta.ndarcfs.-.::.- would. , represent ··-:-a··- commitment'· ·'to. • ..... "::.'<::: 

technoloqy-forcinq by the Agency, ..... ith a potential need for a 

delay at a later date. The alternative would be less stringent 

non-trap standards, such as 0.5 and 5.0 g/BHP-hr, respectively, 

which would provide little additional control over the 1987 

standards. 

A disadvangage of Option 2 is its effect on future HDD 

trap development. As alluded to earlier, .there is strong 

evidence that significant development of a new control 

technology only occurs in response to the prom.ulgation of a 

stand~rd requiring its use. Thus, if a trap-based standard is 

not proposed and promulgated for 1990, HOD trap development 

will not progress and will appear no more implementable in lq90 

than it does now. 

On the other hand, the near-term promulgation 

trap-based HOD standard for 1990 would also represent 

commitment by EPA to technology fore inq. The problems 

of a 

a firm 

facing 
42 

HOD trap implement~tion are sufficiently significant at the 

present time, as were those facing LDD trap implementation in 

1979, that there is a fair orobability that the standard may 

not be feasible by 1990 and may reauire some delay at a later 

date, and a continued · commitment to its even tu al 

implementation.· Thus, compliance with this option may be no 

more difficult than compliance with the second option, though 

the technical issaes involved would be very different (engine 

related vs. trap related). However, the trap-based option-· 

would, or course, provide more control than the non-trap 

approach, so it has this advantage over Option 2. 

With respect to the le~el of the trap-based standard, 0.25 

g/BHP-hr would appear most aopropriate. The requirement that 

essentially all HDDs be equipped with high-efficiency 

trap-oxidizers via a O .1 a/BHP-hr standard would be difficult· 

to justify for 1990. The NOx standard would still be 4.0 

g/BHP-hr as this level appears to represent the limit of 

technology reaardless of whether traps are applied . for 

particulate control. 

'!'he ootion of implementing an urban vehicle strateqy is 

also available in the 1990 timeframe. '!'here are still some 

questions surrounding its cost, oarticularlv for buses since 

the economic viability of tra.nsit authorities could be 

seriously weakened by any additional costs. However, these 

costs could be mitigated by a Government subsidy for methanol 

use bv transit authorities which would eauate the cost of . methanoL. and diesel· fuel: on an. ene·rav basis. ··This would. be' .. -~.:. 

,. consi.stent with exl.stinq aovernment·- suooort of the basic 

availability of urban transit, only adding-~upport for emission 

control as well. ·Privat.e fleets should be much better able to 

absorb such costs, particularly since many such fleets will be 

switching to diesels from gasoline engines. '!'hey will have the 

option to stay with the gasoline engine, in addition to. the 

options of paying for the additional cost of a trap-oxidizer 

methanol engine: the methanol option only being viable for 

those ooerators with central fuel depots. 

Technical feasibility would not be an issue for those 

vehicles for which methanol is a viable option, since methanol 

engines should be easily producable. However, for those other 

vehicles, traps would be reauired. Given that only Class VI 

and lighter vehicles would be involved, trap feasibiliy should 

be more easily demonstratable than with respect to all HDDs, 

since LDDT trap experience should be more applicable. 

Overall, then, there appears to be only one option for 

1987, a 0.6 g/BHP-hr particulate standard and a 6.0 g/BHP-hr ~Ox standard. Three options appear viable for 1990. One, 
43 

particulate and NOx standards of 0.4 and 4.0 g/BHP-hr, 

respectively, for all HDDs. Two, standards of O. 2 5 and 4. O 

g/BHP-hr, respectively, for all RDDs. ~hree, standards of 0.25 

and 4.0 g/BHP-hr, respectively, for Class VI and lighter HDDs 

and transit buses· (and possibly 9arbage trucks ·and cement 

mixers) and standards of 0.4 and 4.0 g/BHP-hr, respectively, 

for all other f.-tODs. With the third option, the emissions of 

methanol engines would be included in the averaging process. 
44 

References 

l. "Regulatory Analysis of 

'Particulate Reaulations for 1982 

Liaht-Duty Diesel Vehicles," U.S. 

Sources, ~ebruarv 20, 1980. 

the 

and 

EPA, 

Light-Duty Diesel 

Later ·Model Year 

Office of Mobile 

2. "Draft Reaulatorv 

?articulate Requlations," U.S. 

December 23, 1980. 

Analysis: ~eavv-dutv Diesel 

EPA, Office of Mobile. sources, 

3. "Health, Soilina, and Visibility Benefits of 

.~lternative Mobile Source Diesel Particulate Standards," Final 

Report, SPA Contract No. ~8-01-6596, Mathtech, Inc., Princeton, 

NJ, December 1983. 
Part II 

Supporting Technical 

Analyses 
CFAPTER 1 

TECHNOLO<;Y 

t. Introduction 

The major reductions in diesel particulate emissions 

available from engine modifications have already been achieved, 

with the possible exception of electronic control of the fuel 

injection system. Further major reductions will need to be accompli~hed throu9h the use of trap-oxidizer systems. 

Under the current light-duty diesel vehicle (LDDV) and 

liqht-duty diesel ~ruck (LOOT) particulate standards of 0.6 

gram per mile (g/mi), no traps are necessary. Since heavy-duty 

diesels (HDDs) are not currently subj~ct t~ a particulate 

standard, traps ar.e not found on current HDDs. either •. However,. 

the more s tr ingen t particulate standards of the base scenario 

will require traps on many diesels. This chapter investigates 

each manufacturer's need for trap-oxidizer svstems under the 

LDDV, LDD~, and HDD particulate standards of the base scenario, 

as well as determining the non-trap particulate emission levels 

which would occur under less stringent particulate standards of 

the relaxed (non-trap) scenario. 

This chapter is divided into three sections, each in turn 

addressing LDDVs, LDDTs and HDDs. The section addressing LDDVs 

is the most detailed, as the methodoloqy :or all three sections 

is therein described. The latter sections onlv reference this 

methodology. · 

The LDDV section itself consists of five parts. The first 

simPlv describes the source of the enaine-out LDDV particulate 

levels used in the ana 1 ys is. The second adar esses the 

NOx/particulate trade-off issue and establishes NOx/particulate 

1 . h' b d . .. . t' 1 t .. ·· ::·::~--·re ~t1~n_.s ·H,s- ... to .. , e_- .us.e ... 1n, .. , .. ao:JUSt1nq.'. par .1cu a. e ...... em .. 1ss.1.q_.O,,.:,,, .. ,, ..... ,,._,. leve1s ·to va·fyfng· NOx ···leve•ls~ ·1.:wnile these r·elation·ships ·-wi:l.l.._ .. 1 .. -,~·"· 

"'ave onlv a limited use here in ad~ressinq the base 

scenario--most LDDVs are at NOx leve 1 s near those appropriate 

to comply with the base scenario's 1.5 q/mi NOx standard--they 

will be of siqnificant use in addressing the sensitivity of the 

results of this chapter to varying LDDV and LDDT NOx standards 

(see Chapter 11). The third part of the LDDV section estimates 

the equivalent "standard" levels that each LDDV engine 

configuration could meet without traps and. the fourth part 

converts these engine configuration levels into corporate 

aver age non-trap standards achievable by each :nanu f acture r (the 

relaxed scenario). The fifth and final part will then 

determine the percentage of LDDVs which . will require traps 

under the base scenario (0.2 g/rni particulate and 1.5 g/mi NOx 

standards with corporate averaging). 
1-2 

It. Liqht-Dutv Diesel Vehicles 

A. ~urrent Levels of NOx and Particulate Emissions 

The most convenient and accurate source of current LDDV 

ena ine-ou t oar t icula te levels is the new-vehicle certification 

program. The first model year in which LDDV manufacturers had 

to certify to the current 0.6 gram per mile (g/mi) particulate 

standard was 1982. >1owever, some manufacturers chose to test 

for part icu late s in the 19 81 model yea·· and then carryover the 

results for the 1982 model year ther-" spreading out the new 

erniss ions testing program over two y: , • Thus, certification 

test results for LDDV particulate are orimarilv available for 

the last two years (ie., the 1982 and i983 model years), with 

some ~ata beinq available from the 1981 model year as well. 

All of the 1983 model year LDDV enqine families wer~ 

subdivided into configurations on the basis of transmission 

type and inertia weight class. The available 1981-83, NOx and 

particulate test data were then obtained for each of these 

configurations. These data included emission tests plus fuel 

economy tests during which emissions were also measured. Both 

manufacturer tests and EPA tests were included. 

A review of the test results of configurations for which 

testing had been done for both the 1982 and 1983 model years 

did not show a clear pattern of change from one year to the 

next, although there was a modest trend for both NOx and 

part icu late to improve with the mo re recent data. There fore, 

it was concluded that only the most recent (1983) test results 

should be used here when available. Rowever, in t~e cases 

where 1983 engine configurations wer§! --~arried oyer from 1982 

a'nd "no"'- 19.93.:.. ·.data were"'· ava.i1:.ib1e;·• . .,-. "the 1982 .Tmod.el•• year 

certification test results were used. 

These most recent test results for each configuration were 

then examined and outliers excluded before determinina the mean 

for each configuration. In general, outliers were test results 

greater than 140 percent or less than 60 percent of the mean of 

the rest of the test results for that confiauration. This 

range may have been somewhat greater or smaller depending on 

the observed soread and total number of tests. 'l'he remaining 

test results for each configuration were averaged and the 

resultant means used as the current level of :-70x and 

particulate emissions for each configuration. These 

engine-configuration means are shown in Table 1-1. 

B. The NOx/Particulate Tradeoff 

Having established the 

emission levels, an estimate 

level would chan~e if the NOx 

decreased was made. Such an 

current ~Ox and particulate 

of how the particulate e!Tlission 

emission level we.re increased or 

analysis was primarily necessary 
1-3 -

-

Table 1-1 

Actual, Certification LDDV' 

Particulate and ~ Emission Levels 

Engine Inertia Weight Displacement Particulate t-l)x 

Manufacturer Family Trans. Class (lb) (liters) I1"n' ( o/mi) rMI' (a/mi) 

General Motors Z90 MS 2,500 1.8 .17 1.11 

Z90 L3 2,500 1.8 ·.13 1.01 

ZK7 L3 3,000 4.3 .22 1.04 

ZK7 L3 3,500 4.3 .25 1.10 

ZT8 L3 3,500 4.3 .21 1.23 

m L3 4,000 5.7 .32 1.21 

ZT7 L3 4,500 5.7 .37 1.14 

'l:r7 !A 4,000 5.7 .37 1.11 -- ZT7 !A 4,500 5.7 .40 1.18 

Volkswagen MO M4 2,250 1.6 .16 .90 

M>t:J MS 2,250 1.6 .19 1.02 

MO A3 2,250 1.6 .18 1.01 

JNJ MS 2,500 1.6 .19 1.02 

J'AO A3 2,500 1.6 .17 1.10 

AZ8 MS 2,250 1.6 .22 1.12 

AZS - MS 2,500 l.'5 .20 1.10 

AZ8 A3 2,500 1.6 .29 l.14 

AAS 54 2,250 l. 6 .18 1.02 

BZX A3 2,750 1.6 .18 1.22 

BZX MS 2,750 1. i; .22 1.19 
1-4 

Table 1-1 (cont'd) 

Actual, Certification LDDV 

Particulate and '.'l)x Emission Levels 

Engine Inertia Weight . Displacement Particulate ~ 

~anufacturer Familv Trans. Class (lb) (liters) !Mr (a/mi) ~ {a/mi) 

Nissan AF8 M4 2,250 1. 7 ;17 .82 

AF8 MS 2,250 1. 7 .20 _q4 

AF8 MS 2,500 1. 7 .23 1.00 

AFB A3 2,250 1. 7 .24 • 89 

AF8 A3 2,500 1. 7 .23 .92 

Aro MS 3, 500 2.8 .22 1.16 

--- AfU L4 3,500 2.8 .24 1.32 

Mercedes-Benz 501 M4 3,500 2.4 .42 1.11 

501 A4 3,500 2.4 .38 1.15 

508 A4 4,000 3.0 .43 1. 26 

Isuzu CD7 M4 2,500 1.8 .19 1.09 

CD7 MS 2 ,500 1.8 .17 1.21 

CD7 MS 2,750 1.8 .18 1.17 

CD7 A3 2,750 1.8 .16 1.29 

Audi BZ7 MS 2,750 1.6 .22 1.19 

3Z7 A3 2,750 1.6 .17 1.21 

CZ3 A3 3,000 2.0 .19 1.23 

BAX MS 2,500 1. i; .21 1.08 

Peugeot AAl MS 3,500 2.3 .28 1.04 

AAl A3 3, 500 2.3 .30 1. 01 

BA.3 M4 3,500 2.3 .32 .87 

RA3 A3 3, 500 2.3 .40 .98 

Volvo AY2 M4 3,500 2.4 .29 1.37 

AY2 A3 3, 500 2.4 .27 1. 31 

TRO ~ 3,500 2.4 .29 1.17 

'!'BO A3 3, 500 2.4 .23 1.19 

. .... .. ·.-:~i~ .. :.":..":"'::;- '. .. ------- .... -. . ........ ..... _ ll."!"'~ • : ........... - . .:.. ,,~ ... ~ 

.. .. - - ·- ....... ~ . ... - .. 
1-5 

so that the particulate emission level of each configuration 

under the various NOx standards being considered in the 

sensitivity analysis could be estimated. f.fowever, it is also 

useful here, since many engine configurations are emittinq NOx 

well below the leve1s required by a l. 5 g/mi standard and· some 

adjustment of their particulate levels would appear appropriate. 

Assumina that only injection timing retard or EGR is used, 

the general shape of a NOx/particulate tradeoff curve is known 

to be (~Ox emissions in ·the x dimension and oar t icula te 

emissions in the y dimension): 1) negative in slope at all 

points, 2) steeply ~~oped ~~ low NOx levels, and 3) qently 

sloped to flat at ~iqt:i ___ NC2".C __l_evels. Furthermore, it is 

oene ral 1 y 1«nown that the curve shifts outward ( ie. , uoward s and 

to the right) with increasing enaine displacement. Fioure 1-1 

shows qeneralized NOx/particulate tradeoff curves and 

illustrates this shifting effect of engine displacement. 

Ideally, the specific tradeoff cu.rve would be known for each 

engine family/confiouration. However, such curves are not 

available. Therefore, an approximate method was develooed for 

predicting particulate emission levels from known NOx lev'els. 

First, in order to account for the s':iftinq of the curve 

that occurs with changes in enaine displac~~ent, the 1983 model 

year engine families were divided into the following three 

groups: small engines (l.6 to 1.8 liters), medium enaines (2.0 

to 2.8 liters) and large engines (3.0 to S. 7 liters).- '1'he NOx 

and particulate emission levels were then plotted for each 

configuration within each engine size croup. 

The NOx emission levels for the small enaine group range~ 

. .- _ , ~ t9...1!! . ~.-~. 3 .. o,". ,tg7 ,1.,2 9. ':9/iJJ.~ ~_;;-:;.J'h ~- ., q_ ~.s.tr:.ib.u.~.i o~··: o.f. poi nJ: s . ~PP~?.~.ed .. ,.t.o_." .. ,"·~ .... ~,, ,_ .. ·o __ hav.e. a s.l_ight·ly .· ... n.e.g,a.tLv..e .. ,.:,.slope ·.which ·•,·r:egress ion ·of the· datia'-~: . :L " .. ; • 

confirmed. The emission levels of one configuration (VW, 

engine family .a.zs, A3 transmission, 2500 lbs.) were excluded 

from the regression because the ~Ox/particulate combination was 

well outside the range of all of the other values includinq 

other values for that same engine family. 1'he slo~e of the 

regression line was -0.033. This slope is quite small, as will· 

be seen later when compared to those for the larger engines, 

and is qenerally in. line with what would be expected for small 

enaines.fll Therefore, it was used to pr~dict changes in 

particulate emission levels resulting from changes in NOx 

emission .levels below an ahsolute NOx level of 1. '35 a/mi. '!t 

was assumed that no further reduction in particulate would 

occur for NOx emission levels greater than 1. 3 5 g/mi (i.e., the 

slope was considered to be zero). [lJ 

A NOx emission level of 1.35 g/rni was chosen as the 

·reference point to change slopes for the small engine group 

(and the other two qroups) for two reasons. First, the great 

majority of current LDDVs have NOx emissions less than 1.35 

g/mi. Since the slopes obtained by the regression of the data 
-

·~ 

.... I -: I 

:.. 

. :; ...- =~-.=;r::.\:-:, I 

Generalized ":',,.,s--,,.·•--a 

---- --~'-'-··. 

1-6 

Figure 1-1 

Shape o: ~Ox/?a:~:=~late ~=adeof: 

~~e Sh~=~~~a·!!:ec~ d o: ~~c~~e d Dis~lac~ent I 

- . .:.::;:.nes 

~- .:c ............. . . .... . . ~· . ~·~ ............ ·~.,. 

......... -..... ~ 

~ex 
l-7 

are most appropriate within the distribution of data, it was 

decided to limit the applicability of the regressions to this 

level. Second, 1.35 g/mi is approximately the engineering 

objective (or low mileage target (LMT)) for the NOx standard of 

the base scenario ( 1. S g/mi) • (The NOx standard of 1. 5 g/mi ~inus a 10 percent safety margin and divided by a deterioration 

factor (DF) of 1.000 (which is typical for diesel NOx 

emissions) yields a LMT of 1.35 g/mi.) 

The plot of the emissio~· levels for the medium engine 

group, whose NOx values ranged from 0.87 to 1.37 g/rni, appeared 

to have a qreater negative slope than the small engine aroup. 

Regr~ssion of the data -confirmed this, showing .a. slope of 

-0. 201. As this slo9e appeared reasonable for enoines of this 

size, based on the limited information available on current 

NOx/par t icula te tr adeo ff curves ( 1 J and the fact it was larger 

than the slope for the small enq ines, this slope was used to 

predict the change in particulate emission levels for chanqe s 

in NOx emission levels below 1.35 g/mi NOx. Again, two 

configurations' emission levels (M-B, 2.4L, both transmissions) 

were not used in the regression because they definitely 

appeared to be outliers. The slope of the tradeoff curve for 

NOx emission levels greater than 1.35 g/rni was somewhat 

arbitrarily reduced by one-half to -0.100, since it is known 

that the curve becomes flatter at higher ~JOx levels, but by an 

unknown maqnitude. 

~or the large engines, the slope of the tradeoff curve for 

NOx values below 1.35 g/mi was not based on a regression of the 

data, but was simply estimated to be -0.400 based on known 

tradeoff curves for large, albeit older, engines.[l] This was 

............ ____ necessarv because there were only 9 data points for the laroe · - _';"~ '.:, .en'g.i"ties· -·-·and 'n¢>"·~cor r·e ~;at ion - ex i s·ted·~ --·':t:he· -.slope-.. f or,JJ.Ox,. value_~:, .... · ... :.,,. 

greater than" t.·35"'"g/mf' was· also·"·estimat"e"<J° -u·s·ing enqineeri'ng····-·-

judgment and was set at -0.100. At first a slope of -0.200 was 

estimated, based on the judgment that this slope should be 

steeper than that for the medium-size engines. However, this 

produced some unrealistically low particulate values at the 

higher NOx values being examined in the NOx sensitivity 

analysis, so -0.100 was chosen instead. 

c. Engine Confiauration's tow-Mileaae Targets ani1 

Standard Levels 

Usina the slopes of the tradeoff curves determined above 

and the data in Table 1-1, the particulate low-mileage tar(let 

(LMT) at 1.35 g/mi NOx was calculated for each configuration. 

T!ie particulate standard leve 1 for each configuration was then 

calculated for these particulate L~Ts. This was done by 

multiplying the particulate LMT by the appropriate 50,0.00. mile 

deterioration factor (DF) and the appropriate safety marqin. 

Both factors are explained below. 
1-8 

The particulate DF used for each . configuration wa.s the 

cert1f ication DF for the 1983 model year except in three 

instances. The three exceptions were enaine families* with DFs 

much greater than the other 18 engine families. Fifteen of the 

21 total engine families had particulate DFs less then 1.10. 

Another three engine families had ~articulate DFs between 1.10 

and 1.15. The last three engine families had particulate DFs 

greater than 1.24. It was concluded that the manufacturers of 

these last three engine families could lower the DFs to at 

least the 1.15 level if a more stringent particulate standard 

required them to do so. Therefore, for the purposes of this 

study• a DF ~f 1.15 was assumed for ~ach of those three engine 

families. 

The safetv ma rains necessary for calculating the 

particulate standard levels from each particulate LMT were 

determined using the methodoloqy developed for past EPA 

rulemakings. [2] That methodology requires a coefficient of 

variation (COV) for production-line vehicles and the number of 

prototype vehicles tested before a manufacturer fixes its 

design. Results from EPA's Selective Enforcement Audit (SEA) 

testing program[3] indicate that the LDDV particulate COV is 

slightly less than O .13. .!\lso, the number of prototype 

vehicles to be built and tested was presumed to equal the 

maximum considered in the methodoloqy (seven), since the engine 

technology exists today and manufacturers will have more than 

sufficient data upon which to base their LMTs. Thus, the 

safety margin as interpolated from the table[2] would be seven 

oe rcen t. P.oweve r, since available SEA test data on LDDVs is 

limited and the oarticulate COV mav increase somewhat with more 

str inaent ~Ox and/or particulate .standards, a somewhat larger .. ··"'--"~·- saf.et:~i--nfa(s1~h':,Jff.·.1o··peX:9~nt. w~s use-d.··fgr ·th·is~$tt;i·dy.-_.. ·· ... -.,.-.;.-. - ...... - ·..o~l~ < --·· ..... - ••••• ·-. ....... .. --- ···-

The oarticulate standards achievable bv each confiauration 

are shown in Table 1~2. An industry-wide, non-averagin9, 

non-trap, non-technoloay forcing particulate standard can be 

determined by simply identifyinq ·the confiauration with the 

highest particulate standard listed in Table 1-2. Thus,. for 

the NOx standard of 1.5 q/mi, such a particulate standard would 

be O .43 g/mi (M-B, 3 .OL engine). 

It should be noted that this highest emitting 

configuration, as well as the next three highest emittin9 

configurations, seem to be technology outliers. Three out of 

four of these configurations are Mercedes-Benz (M-8) vehicles. ~hen the emissions of these M-8 vehicles are compared to t~ose 

of other similarly sized vehicles, one finds that the M-B 

* Engine families, rather than configurations, are 

considered here because DFs are only determine.a on an 

enq ine f arni ly basis and are applied to all configurations 

wit~in that engine farni!Y· 
1-9 

Table 1-2 

Achievable Non-Trap, LDOV' Particulate 

Standards Under the 1.5 a/mi NJx Standard 

Part. Std. 

Assuming a 

Engine Inertia Weight Displacement. 1.5 g/mi 

Manufacturer Family Transmission Class (lb) (liters) t-lJx Std. Co/mi) 

General Motors Z90 MS 2,500 i.a· .20 

Z90 L3 2,500 1.8 .15 

ZK7 L3 3,000 4.3 .12 .. 

ZK7 L3 3,500 4.3 .17 

ZT8 L3 3,500 4.3 .19 

ZT7- L3 4·,000 5.7 .33 

ZT7 L3 4,500 5.7 .• 36 

ZT7 L4 4,000 5.7 .35 

ZT7 L4 4,500 5.7 .42 

· Vol'.<swagen MO M4 2,250 1. f5 .17 

MO MS 2,250 1.6 .21 

MO A3 2,250 1.6 .20 

JAO ~ 2,500 1.6 .21 

JAO A3 2,500 1.6 .19 

AZ8 ~ 2,250 1.6 .27 

AZ8 .MS 2,500 1.6 .24 

AZS A3 2,500 1.6 .26 

AAS S4 2,250 1.6 .20 

BZX A3 2,750 1.6 .20 

BZX MS 2,750 1. i; .24 

: -."':· :7 •• ::::. · ·• i.:·-=-:·~ ;.";;.!.: ...... ;.·::i- ~!· •.-: e~·i·'l.;--:;··.-.; ·~. :·..-,z-:-;.~::·d- : · ·":·~-:..·i· · :r·: <;.. ·: ·.·>:.:.Y.~···~,tl'l:::'.: :·..:_:~:,·.: "\'.'r."-~·.:t,',. t'E~ ... :-...._~..:-.~(·;t- :"" .. ·• ·.:r ~ .. !' ., .... T ._:. • ? 1._:. .. ~ .... .• .. .... • l. ;,~. ::.:· ::;_·r.. ~~-=· · ·-~-;... ..;:"· .. ~-r.: :· :::· ::- :.~: ;, 

.. ~ .••• :·;,' ....... • ;,.~.: •. ~ .... '.~_ .. : •. 4 ••• ~-.;..t:.: ~ ...... ~-.;~·):.:~ ..... ~,~· - ._ ..... _ .... ,· .... ,,fl•~·····- .... _.,. ~-.··1.-~ .. : :··ff ... ,-i·· ... ·:~.·a.:-·-? ....... -... ::.;. 
~anuf acturer 

~issan 

Mercedes-Benz 

Isuzu 

Audi 

Peugeot 

Volvo 

........... ... ,-,... 

. -. ~ ,., ·~ _ .... < -

.. 

Engine 

Family 

AF8 

AF8 

AF8 

AF8 

AF8 

Aro 

AFO 

501 

501 

508 

CD7 

CD7 

CD7 

CD7 

3Z7 

BZ7 

CZ3 

BAX 

.?\Al 

AAl 

BAJ 

PA3 

AY2 

.'A.Y2 

1-10 

~able 1-2 (cont'd) 

Achievable Non-Trap, LDOtJ Particulate 

Standards Under the 1.5 o/mi ~ Standard 

Inertia Weight Displacement 

Transmission Class (lb) (liters) 

M4 2,250 1. 7 

MS- 2,250 l. 7 

MS 2,500 1. 7 

A3 2,250 1. 7 

P.3 2,500 l. 7 

MS 3,500 2.8 

rA 3,500 2.8 

M4 3, 500 2.4 

A4 3,500 2.4 

A4 4,000 3.0 

M4 2,500 1.8 

MS 2 ,500 1.8 

MS 2,750 1.8 

A3 2,750 1.8 

MS 2,750 1.6 

A3 2,750 l. 6 

A3 3,000 2.0 ~5 2,500 1.6 

!-15 3,500 2.3 

A3 3, 500 2.3 

M4 3,500 2.3 

A3 3,500 2.3 

M4 3,500 2.4 

A3 3, 500 2.4 ·TSO-''-~.,=>;,c· -·:-··-Ms-·::,····· .. ·: ':: .. r•· ..... 3,·500-······ "'' .,., ""••·2·.-4·· ·-··· 

Part. Std. 

Assuming a 

1.5 g/mi 

~ Std. (g/mi) 

.20 

.24 

.28 

.29 

.27 

.22 

.28 

.41 

.37 

.43 

.22 

.20 

.21 

.19 

.24 

.19 

.19 

.25 

.24 

.26 

.25 

.36 

.36 

.32 

..• 32- . ....... ·' ·"' .· 7Bo ::_, ... ~ · - -:.A3 · ' " 3 '500' . .: .. -·· .·.:2;"4 .. : :,-_, -··.-·.·. ". ·- .25 ·-
1-11 

vehicles emit significantly more particulate. 'T'hus, it a!Jpears 

that M-B· has not yet implemented the kinds of combustion 

chamber and injection modifications that have been made by 

others (e.g., General Motors). Presumedly, M-B could do this 

if it became necessary. The fourth configuration is a General 

Motors vehicle powered by their 5. 7 L engine (L4 transmission, 

4500 lbs.). It has been rumored that this enaine will be 

eliminated- sometime in the next few years, primarily due to 

market considerations, as well as to the fact that this is 

their highest emitting erigine for both NOx and.~articulate. If 

these four co-nf igu-r at ions were exc-luded from consideration 

here, the non-averaging, non-technology forcing particulate 

standard could _.be 0. 36 a/mi, 15. perc.e.nt .. .lower than the O. 43 

a/mi level mentioned abov~. 

D. ~on-Trao "Averagina" Standards 

The ;:>rev ious discuss ion pr es en ted the methodology used to 

estimate particulate LMTs and standard levels for each 

configuration under a NOx standard of 1. 5 g/mi. From those 

results an industry-wide, non-averaging, non-trap, 

non-technoloay forcinq particulate standard could be selected. 

~hat standard was based on the assumption that every LDDV would 

need to be at or below the standard (i.e., non-averagina) ." In 

this situation, most vehicles could increase their particulate 

emissions up to the level of the worst-case vehicle and st i 11 

be in . compliance. While we would not expect such a situation 

to occur to this extreme, it is possible that NOx control and 

fuel economy incen~ives could lead to increased particulate 

emissions if the pacciculate standard allowed it. 

One way to significantly· increase the probability that 

:· ·)~·· ·· ,,. ·• .. _,.,...-indu·s ti::.v-w id e ... ;:.·oa-r·t·i c-u-1 ate . ·'em i-s s io-n S· , .·,o10 ti-1 d · · ·no br-""'::,i n.c.r:e.a s·e"· :: be v:o r:ic:L.~-:.. . --'" ........ . 

... , .. ~ ,; ..... ~ ...... -?'r'es'e'fr't .. -"Y'e:V'e"ls?:·~· an:a: :: ye'F ;., st il F ·.:·s·e f · '"'a··:· no·n·-tech-no log~/: "f O't"C :i:-n·g .. .o; ... :· ),;., ••• '..::: 

standard would be to i~plement a corporate average standard 

(see the introduction to the study for an explanation of 

emissions averagina). TJnder this approach t!"\e non-trap, 

non~technology forcing standard would be numerically lower than 

that determined in the or: ev ious discuss ion s i nee each 

manufacturer could "average"- its high emitters with its· low 

emitters. Because of this, it becomes mor:e difficult for a 

manufacturer to increase the emissions of -its low emitters 

since these emissions are factored into its cor9orate average 

emission level and are no longer irrelevent.- Thus, while 

aver aq ing has been considered in the past only for trap-based 

particulate standards, it also has a benefit for non-trap 

standards. 

Table 1-3 shows the currently achievable non-t.rap, 

non-technoloay forcing particulate standard for each 

manufacturer under averaging. These standards were calculated 

by sales weighting the achievable particulate ~tand~rds for 

each manufacturer's LDDV configurations listed in Table 1-2. 

Sales for each configuration were obtained from the 
* 

1-12 

Table 1-3 

Achievable Non-Trap Particulate 

Standards (under "averaoing") 

Manufacturer 

General Motors 

Volkswagen , 

Nissan 

Mercedes-Benz 

Isuzu 

Audi 

Peugeot 

Volvo 

Assuming 

a 1. 5 g/mi 

NOx Standard 

(a/mi) 

.29* 

.20 

.26 

.42 

.20 

.20 

• 2 6 

.29 

This level becomes 0.16 g/mi if GM's 5.7-liter 

discontinnued and its sales are replaced 

4.3-liter enqine. 

engine is 

by their 

;-, .~:; ~ =. ·~ .... -·~- ,..,: ' ' • r .. • ~ ·"' ••. - ..... ;....- -...._ ••. •• ' - • - ';..:. - • - . - ,.;_ •- .--- - •• l •• ,. .- • r•,. :., • :. ... ·:-· :,..:. -;- • - ~ ..... i.::.. ;:.,. ~ ,...- ,.::. ':".'!' -~i.-.i.·--:· ..., --~·.;~ ·-: _'; ::::. • ·;::_;..,-~. -~;. ,. . ~ .. ·,,: • - - .-• • .,.., ,.,. '"'-
l-13 

manufacturers' 1983 estimated Federal sales required by the 

fuel economy program known as Corporate Average Fuel Economy 

(CAFE).* If the worst-case manufacturer's (i.e., 

Mercedes-Benz) particulate averaging standard level became the 

averaging standard for the industry, then as Table 1-3 shows, 

the particulate ave.raqing standard would be 0.42 g/mi. This 

level is not significantly lower than the 0.43 g/mi 

non-averaging standard of the previous section due to what 

appears to be excessively high emission levels of the .. w.o.r.st:-case ... manufacturer'~-- engines. If this worst-case 

manufaciurer is treated as a technology ·~utli~r, then the 

corporate average for General Motors and Volvo would set the 

indus.try.-wi.d.e_, ___ , ?PrtJ.c;:..ul?t.e_. averaging _s_tandard _at 0.29 g/mi. 

Th is . level is 3 3 percent lower than the non-av_er a_g ing s tandarcf · · · · o f the or e v i o us sec t ion ( 0 • 4 3 g I :n i ) • A non - t r a p-; -- .. · · ... · 

non- technology fore ing, particulate averaging standard of I). 29 

g/mi would moderate the risk that manufacturers of small LDDVs, 

which are low particulate emitters, might substantially 

increase particulate emissions from these vehicles. 

It is interesting to note what would happen to GM's 

corporate average particulate level if it discontinued 

production of its 5.7-liter engine. This could happen if the 

long-range trend towards increased fuel economy eliminated the 

"biq" cars of today whereupon the need for the 5.7-liter engine 

would also be eliminated. Assuming that the vehicles which 

would have had the 5.7-liter engine received instead GM's 

4.3-liter engine, GM's average particulate standard level would 

drop from 0.29 g/mi as shown in Table 1-3 to 0.16 g/mi. 

Furthermore, since GM's estimated sales comprise about 60 

percent of the total LODV estimated sales, lowering GM's 

averaoe particulate standard level by this 45 percent would 

.... , ~· ,_.·-. ,1owe•r·"' t.o ta,l. LDDV. ·pa-.r t i.C:l1:1-at:!! ,_ .. em.is s,iqn.s ... ..S.4J~.~.1;.P-n ~ ~.?. ~l'i ~ . ... ~?~~Y~~:'~'i'"'':·r'.· ~. : ... ·:. ~ ~-···· ···-the "non-tr··ap·, ·n·on-t-echno-loqy.:.,foi:.c1nq., ._ave·r-a91ng. part1.cul_ate ....... ····~ . .:...· 

standard based on the second highest emitter would remain at 

0.29 g/mi {Volvo). 

E. Determination of the Percent of Trao-::ouiooed 

Vehicles 

Thus far, this analysis has been concerned with only those 

particulate standards achievable without the use of 

trap-oxidizer systems. It will now co'nsider the use of traps 

as a particulate control strategy. Here the focus of the 

analysis will differ· from that of the previous section. 

Instead of determining achievable part icu late standards under 

* These projections are confidential and are not presented 

here. The pr es en tat ion of the resu 1 tant 

emission average does not divulge the 

information contained in the projections (i.e., 

sales). 

corporate 

pertinent 

absolute 
1-14 

various scenarios which assume some percent usage of traps (in 

the previous case, zero), this discussion will assume a 

oar t icu late s tanciard of O. 20 g/mi (the base scenario) and then 

determine the percentage of the LDDV fleet requiring traps in 

order to achieve tnis standard. Emissions averaging will be 

assumed to apply as the Agency expects to soon ·finalize a 

particulate averaging program in conjunction with the 0.2 .g/mi 

standard (proposed in 46 FR 62608). 

Two types of traps were considered for compliance with the 

0.20 g/mi particulate standard. One is the wire mesh type and 

the other is the ceramic type. EPA's _ report[41 on the 

feasibility of trap oxidizers indicated that both types appear 

to have good durability characteristics. The ceramic type of 

trap was tested by Southwest· Research Institute for EPA[S] and 

the wire mesh tvoe was tested at this same facilitv for 

Johnson-Mat they, :inc. [ 6] These testing programs indicated that 

the deterioration for both types of traps was negligible and, 

therefore, a DF of 1.00 was used here. , The EPA[41 report 

discusses each 0€ the two traps in detail and concludes that 

the efficiency of the ceramic trap is about 70-90 percent while 

the e f f i c i ency o f the w i r e me sh t r a p i s about 5 O - 8 O pe r c en t • 

As the durability test of the ceramic trap referred to above 

showed an 85 percent efficiency, that figure will be used 

here. For the wire mesh trap, 65 percent will be used as a 

reasonable mean efficiency for a typical trap. This analysis 

will use these percent efficiencies to determine the tail pipe 

emission levels from engine-out emission levels. (For 

simplicity, mixing use of both trap types was avoided.) 

The methodology used to calculate the percentage of 

~-.;.· .. ~--~-- tr,ap."!' equ.-i ppe.d"."v_ehtc1.e s- ,.f.o.r .. each_ .. typ.e .. _qf _.J:~.a p;. a.r\Q ... , !11qJtl1.~,P..q,t,.u;: ~!-,,.-«= ... ,.,_ 

· ·· -· is · s tr a i gh t"f o rward. ·-- :-F-i-r·s·t, ·'- ·each'="7···:con-f::i:gu r a t.i.on-~-s - estimated .,.. ,_.,.. 

sales was multiplied by that configuration's non-trap standard 

level taken from Table 1-2. These results were then summed to 

obtain the total number of vehicle-grams per mile (veh-g/mi) 

from which each manufacturer would begin its control efforts. 

Next, each manufacturer's total estimated sales were multiplied 

by 0.20 g/mi to give the total veh-g/mi that the manufacturer 

would be allowed under each particulate averaging standard. 

The difference between the two figures is the amount of control 

each manufacturer needs to achieve. It was assumed that a 

manufacturer would put traps on its highest emitters first 

because the g/mi reduction achieved is ~ighest for those 

vehicles. 

To determine the number of veh-g/mi saved by putting a 

trap on a given configuration, that configuration's particulate 

. LMT was first multiplied by one minus the trap efficiency and 

then multiplied by that configuration's particulate DF. 1'his 

result was then transformed into a new particulate standard 

level by adding a safety margin of 10 percent or 0.02 g/mi, 

whichever was greatest, because 0.02 g/mi was considered the 
1-15 

minimum acceptable safety margin. The new particulate standard 

level was then multiplied by the estimated sales for that 

configuration to give the new total veh-g/mi emitted. The 

difference between the total veh""g/mi without traps and the 

total veh-g/mi with traps was counted as controlled veh-g/mi. 

Calculations were made for each configuration · until the 

controlled veh-g/mi equalled or exceeded the amount of veh-q/mi 

that the manufacturer needed to control in order to meet the 

O. 2 q/m i particulate st~ndar d. For the most part, only enouah 

traps_ .were .. assumed . installed_. ~o ._just meet. the standard. 

However, in a few instances where the percentage of traps on a 

given configuration a pp roached 8 0 percent it was assumed that 

.. the whole configur.at.ion would- be equi;;iped with traps. 

The results of these calculations are shown 

Assuminq ceramic traps, 22 percent of all LDDVs 

traps to comply with the 0. 20 g/mi standarr1. 

mesh traps, this figure increases to 30 percent. 

III. Liaht-Dutv Diesel Trucks 

in Table 1-4. 

would require 

Assuming wire 

The methodology used to estimate the non-trap, 

non-technology forcing, particulate standards for each LDDT 

configuration was the same as that used for LDDVs. The current 

particulate emission test levels for small LDDTs {i.e., engine 

displacements from 1.6 to 2.3 liters), whi:h were obtained from 

certification test results, were used to calculate the 

oarticulate standard levels shown in ~able 1-5. The ~Ox 

emission levels of the majority of these configurations were 

between 1. 35 and 1. 7 g/mi. Since t!1e NOx/particulate tradeoff 

curve for small LDDV engines was flat i~ this region, no 

adjustment was made to the small LOOT certification values in 

. ;,.,,Jder iv·i ng .· t·h-e .,.~a-r tict.ll~·te t.MTs:. ·. , .. ,. rFO r :.:the . f u 11-s 0i:.ze·· ~LDOT-S· . H·-·e .• -.. ,.· '" ,..; ,., ,., 

enai:ne .-Esplacements of' 6.2 liters) the cur.rent .. ?articulate'·· · 

emission test levels were adjusted to their equivalent at 2.05 

a/mi NOx using the same NOx/particulate tradeoff curve (slope 

of -0.100) as that used for larae LDDVs. (.;LOOT NOx level of 

2 .o·s g/mi under a 2. 3 g/mi :--JOx- standard is equivalent to the 

1.35 q/mi NOx level for LDDVs. Also, the -0.l slope curve was 

the only one needed since the certification ~Ox emission tevels 

of the full-size LOOTS were all above 1. 5 g/mi.) As shown in 

Table 1-5, the industry-wide, non-trap, !ion-technology forcing 

particulate standard without averaging would be 0.40 g/mi. 

·Table 1-6 presents each LDDT manufacturer's non-trao, 

non-technology forcino, ?articulate standard under the 

averaginq concept. These levels were calculated using the same 

methodology as was previously described for LDDVs. The highest 

averaqe particulate level is for Mitsubishi at 0.39 g/mi •. ~ote 

that this level is well above that for GM {l').28 g/mi), which 

only produces ful 1-s i ze LDDTs. Thus, if Mi tsub ish i were 

considered controlling, there is very little diff~rence between 

the non-averaging and the averaging non-trap standard for LDDTs. 
.1-16 

Table 1-4 

Per_2ntage of LDDV Sales Requirinq Traps Under Various 

Particulate Standards (assumes "averaging") 

~anufacturer 

General Motors 

Volkswagen 

NissanMercedes-Benz 

Isuzu· 

Audi 

Peugeot 

Volvo 

Industry-Wide 

Sales-Weighted 

Percentage 

1.5 a/mi NOx Standard 

0.20 g/mi 

Particulate 

Standard with 

Ceramic Trap 

26.8 

0 

25.6 

5 5 • so 

2.2 

30.3 

34.4 

22.3 

0.20 g/mi 

Particulate· 

Standard with 

Wire Mesh Trap 

36.2 

a 

33. 4 

79. 6" 

0 

2.9 

39.5 

44.2 

30.2 
1-17 

Table 1-5 

Achievable Non-Tra?, LDCfl' Particulate 

Standards Under the 2.3 a/mi ~ Standard 

Engine Inertia Weight Displacement 

Manufacturer Familv Transmission Class (lbs.) (liters) 

Small r..oors: 

Ford AGS M4 3,000 2.2 

Isuzu CD3 M4 2,750 2.2 

M4 3,000 2.2 

MS 3,000 2 .• 2 

Nissan AF9 M5 3,000 2.2 

Mitsubishi FOO ~ 3,000 2.3 

M5 3,500 2. '3 

Toyota BBS MS 3,000 2.2 

FF9 MS 3,000 2.2 

Volkswagen P~2 M4 2,250 1.6 ~5 2,250 1.6 

~ MS 3,500 1.15 

~ 4,000 !..15 

Toyo Koqyo KK9 MS 3,000 2.2 

Full-Size LDITTs: 

·General ~tors · ·Z·40 M4 -4 ,500 ... ···6~·2 .. - ' -"· . •' ..... L4 .. ·. 6. 2 

M4 

L4 . 

M4 

IA 

L4 

••.4 i 500. 

5,000 

5,000 

5,500 

5,500 

6,000 

6.2 

6.2 

6.2 

15. 2 

6.2 

Part. Std. 

Assuming a 

2.3 g/mi 

OOX Std. (g/mi) 

.29 

.28 

.26 

.25 

.35 

.39 

.38 

.17 

.25 

.26 

.38 

.27 

.33 

.29 

. .•.. 32 ... ·-

• 35· .. 

.26 

.28 

.40 

.26 

.36 
1-18 

Table 1-6 

Achievable Non-Trap Particulate 

Standards Under "Averaaina" < c 

Manufacturer 

Small LOOTS: 

Ford 

ISUZU 

Nissan 

Mitsubishi 

Toyota 

Volkswagen 

Toyo Kogyo 

Full-size LOOTS: 

General Motors 

Assuming a 2.3 

a/mi NOx Standard 

.29 

.25 

• 3 5 

.39 

.19 

.31 

.29 

.28 
1-19 

As in the LDOV case, the percentage of LDOTs requiring 

trap-oxidizer systems under the base scenario (0.26 g/mi 

part icu late standard) was determined. 'I'he methodology used to 

determine this perc~ntage was the same as for LDDVs except that 

small and full-size LDDTs were considered separately. 'I'his was 

done because the ratio of sales of small to fuli-size LDDT 

sales is expected to change significantly by the mid- to- late 

1980s. A studyf7J by Jack Faucett Associates (JFA) projects 

that in 1987, 86.S percent of all new LDOT sales will be 

full-size while only 13.S percent will be small. 

Manufacturers' LDDT sales estimates for the 1983 model year 

indicate that currently full-size LDDTs represent about SS 

percent of all LDDT sales. ·Thus, a substantial change is· 

expected to occur over the next several years. Therefore, the 

percent of traps required by each LDDT-size group was weighted 

according to the findings by JFA and then combined into a 

sinale LDDT percentaqe. 

Table 1-7 presents the percentage of sales· for each 

manufacturer that would require ceramic traps under the 0.26 

o/m i particulate standard. :or s impl ic i ty these calculations 

were not done for the wire mesh trap, as the effect of using 

wire mesh traps instead of ceramic traos was estimated in 

Section It.E. for LDDVs and, given prese:it data, the ceramic 

trap appears to ~ave advantaoes over the t~e wire mesh trap in 

terms of cost and trapping efficiency. If the percentages of 

wire mesh traps required per manufacturer were desired, they 

could be easily approximated by applying the ratio of the 

;Jercent of LDDVs which would require wire mesh traps to the 

?ercent of LDDVs which would require ceramic traps (see Section 

II.S.) ••. "'T,··· '.~·~ ... -.... ~·.- .. ;~ ~'{"' ... .• ","!'.' ··-~. ; ..... -~ .... . .... " . "''.; .. ~ -· . . ~ .... . .... ,,:.• ~ 

i'·r-am .T.able r.:.7, the indust:rv·-w'"ia·e 

would require ceramic traps under 

estimated to be 7.6 percent. 

IV. Heavy-Duty Diesels 

. :: ~ .... ~ .. oetcentage of ·sales that 

the base scenario is 

A. Current Emission Level and Non-Trac Standards 

Currently there is no particulate s tanda·rd for heavv-du ty 

ciiesel engines (HDDEs). Therefore, there are no certification 

test data f.rom which to determine the current levels of HOD 

particulate emissions. However, there has been a substantial 

amount of qoo particulate testino over EPA's new transient 

cycle by both ·EPA and the ind~stry. Table 1-8 contains 

particulate and NOx emission data from ~anufacturers' 

production and development tests,[81 the EMA/EPA HOO 

"round-robin" testing program, [91 and SPA's original diesel 

transient baseline(lOJ (for those engines for which more recent 

data are not available). Althouqh data are not available for 

every HOD engine family, a large majority of sales is 

represented. Sales weighting the data in Table 1-8 indicated 
1-20 

Table 1-7 

Percentage of LOOT Sales Requiring Traps Under Various 

Particulate Standards (assumes "averaaing") 

Small LOOTS: 

Ford 

Isuzu 

Nissan 

Mitsubishi 

Toyota 

Volkswagen 

Toyo Koqyo 

Full-Size LOTS: 

General '.'-1otors 

Industrv-Wide 

Sales-weighted . -: - ··"' ·.- · ?ercent·aae :. 

0.26 a/mi 

Part. Std. with 

Ceramic Trao . 

12.3 

o.o 

31. 9 

40.l 

o.o 

15.4 

l l. c; 

6.9 

i.6 

. - ··~-·.~ ·-·. ~ 
1-21 

Table l-8 

Low-Mileage, Transient Emissions 

From Current qeavv-Dutv Diesel ~naines 

Manufacturer/ 

F:ngine 

Caterpillar 

3208 

3208 

340/i 

340 6 

33015 

3306 

Cummins 

DINA 

DIT 

DITA 

PCTA 

DITA 

PCTA 

NTC 290 

NTC 350 

NTC 350 (3ig Cam) 

NTCC 240 

NTCC 400 

NH 250 

VTB-903 

Daimler-Benz 

OM 344A 

OM 362A 

Detroit Diesel 

8V-71N 

8V-71TA 

6V-92TA 

" ......... 8V-9 2TA 

··8~2-T· 

International Harvester 

D'!'- 4 61' B 

DTI-4668 

M.acl< 

ETAZ-676 

STSX-676 

P.TSZ-676 

Particulate 

(a/BHP-hr) 

0.65 

0.59 

0.52-0.71 

0.37 

0.73 

o.so 

O.S9 

0.58-0.70 

0.40 

0.77 

0.85 

0.52-0.83 

0. 157 

0.81 

I) • 4 5 

() • 5 3 

0.67 

0.31-0.36 

0. 58 

0.63-0.69 

0. 59 

NOx 

.(q/BHP-hr) 

7.8 

10.0 

7.9-8.4 

5.4 

9.0 

4.8 

8.3 

7.2-9.0 

6.8 

4.8 

5.3 

6.8-6.9 

5. 2 

3.1 

6.7 

5. 7 

f5.7-7.6 

5. 8 .. 7.8 ,_ .............. . · -s .~o--s:.~ 9~- .. _- .. _ .·.-~ ....... _ .... ~ .. ~·· 

5.7 

4. 2 

5.6-5.7 

5. 2 

5.2 

6.9 
1-22 

an average particulate emission 

g/BHP-hr. After allowing for some 

were almost entirely new), it is 

emit at an average of 0.7 g/BHP-hr 

level of around 0.60-0.65 

deterioration (these engines 

estimated that today's HDDs 

in-use. 

Wh i 1 e the 0 • 7 ._ g / B μ P - h r 1 eve 1 i s a po r op r i a t e ·f o r today ' s 

eno in es,. future HDDs should be able . to reach . somewhat lower 

particulate levels with relatively minor engine modifications 

and recalibrations. ~he impetus to control HDD particulate 

(other than the carticles constituting "smoke" at certain 

extreme engine operation modes) has not yet occurred since ther~ has been no particulate standard. With a standard, 

however'. some reduction in particulafe -emissions should occur. 

For example, in its comments to the HDD particulate N"PP.M, [lll 

Caterpillar recommended a future non-trap standard of 0.6 

g/BHP-hr, includino DF and safety margin. ~or the purposes of 

this analysis, t~is level will oe used as the non-trap, 

non-technoloqy forcing, HDDE particulate standard to be 

implemented sometime in the 1987-88 timeframe. Also, for the 

purposes of this analysis, we have assumed that this standard 

would be implemented in 1988. Thus, without the use of 

trap-oxidizers, ~DDEs will be projected to emit at 0.7 g/BHP-hr 

through 1987 and at O.~ g/BHP-hr thereafter. 

B. Standard Level With Traos 

The trap-based HDDE particulate standard of the base 

scenario is 0.25 a/BHP-hr. This level ~as proposed by the 

Agency in its HDDE particulate NPRM (46 FR 1910). The 

percentage of HDDEs that would require traps under this ... ,s.ta.ndard , .. '".is.·- .100 .. · .percent ,,~.e.cause . Jt. .. w~ts .. -. c~~J~Osed, .. as.,·>·<; ...... . - noh-aver.aoing.·- ~.standar.d and .-·--.all · SDDEs :-.:.:_currently.·· emi·L ...... 1 

substantially above 0.25 g/BHP-hr. (The effect of averaging 

will be considered later in this section.) 

The 0.25 q/BHP-hr standard requires a ~O ?ercent reduction 

in particulate emissions from the 0.6 g/BHP-hr non-tra? level 

mentioned above. Both the ceramic trap and the wire mesh trap 

have efficiencies greater than 60 percent. Under the base 

scenario without averaoino, it has been assumed that 

manufacturers would only apply traps of the required efficiency 

regardless of the type of trap used. ~his is to say that even 

if ceramic traps were applied, there would be sufficient 

impetus to reduce efficiency below that achievable (e.g., to 

increase regeneration intervals and reduce backpressure and 

fuel economy penalties) if the standard were more stringent, 

that only the efficiency actually necessary, with a reasonable . safety margin, would be applied. This efficiency has been 

assumed to be 65 percent. Applying this 65 9ercent efficiency 

to the engine-out emission standard level of 0.6 g/BHP-hr, 

results in tailpipe emissions of O. 21 g/BHP-hr under the base 

scenario. This is somewhat lower than the required 0.25 , ... ,,.,, ... , ' I .. 
References 

1. "Light-Duty Diesel NOx-HC-Particulate Trade-Off 

Studies," In: Diesel Combustion and Emissions: ?roceedinqs 

of SAE Congress and Exposition, p. 86, Wade, w. R., SAE Paper 

No. 800335, February 1980. 

2. "~egulat6ry Analysis 

Final Emission Regulations for 

Heavy-Duty Enqines," U.S. EPA, 

184-86, December 1979. 

and Environmental 

1984 and Later 

OANR, OMS, ECTD, 

Impact of 

Model Year 

SDSB, pp. 

3. This Data is Publicly 

Selective F.nforcement Section, 

Division, Office of ~obile Sources. 

Available From the u. S. EPA ~anufacturer's Operations 

4. "Trap-Oxidizer Feasibility Study," U.S. EPA, OAN~, 

O~S, SCTD, SDSB, ~arch 1982. 

5. "Light-Duty Diesel Oraanic Material Control 

Technology Investigation Program," EPA Contract No. 68-03-2873, 

Monthly Progress Report No. 34, August 10, 1982. 

6. Letter from 13. E. Enga, Johnson-Matthey, .~nne M. Gorsuch, Administrator, U.S. EPA, Regarding 

Light-Duty Diesel Particulate Standards, January 25, 

Docket A-91-20, II-D-75). 

Inc. , to 

the 1985 

1982 (EPA 

7. "The Impact of Light-Duty Diesel Particulate 

Standards on the Level of Diesel Penetration in the Light-Duty 

Vehicle and Light-Duty Truck Mar~ets," Jack Faucett Associates, 

For U.S.· EPA, Contract No. 68-01-6375. 

8. 'T'his Data was Submitt~d bv :ieavy-Duty Diesel ::ngine -· .~,. ...... ···:vranuf ac tu re r_s As Comments· · to EPA' s ·H.ea'vy:..·ou't;{"., _· ·,rH·es'"e l'·• ·· · 

?·articulate 'l°PRM "(46 ·rR · 1910) and Can Be Found In EPA -Public 

Docket ~o. A-80-18. 

9. "EM~/'EPA Heavy-Duty Diesel ::naine Cooperative Test 

Program," EPA Public Docket No. A-80-18, November 1982. 

10. "Emissions From Heavy-Dutv Enaines Using The 1984 

Transient Test Procedure, Volume 2 - Diesel," rJ.5. EPA, OANR, 

O~S, SPA-4n0/3-81-031, July 1981. 

lL This Data is Contained In Caterpillar Tractor 

Comoany's Comments to the Heavy-Duty Diesel ?articulate NPRM 

(46 FR 1910). Caterpillar's Comments Can Be Found In EPA 

?ublic Docket No. A-80-18. 
1-23 

manufacturers wil 1 desire a somewhat laraer safe tv ma rq in due 

to the variety of HDD application and the absence of averaging. 

If averaging were implemented along with the 0.25 g/BHP-hr 

standard for HDDEs, the percentage of vehicles requirinq traps 

would drop from 100 ·to about 10· percent. In this case, we have 

assumed that manufacturers would utilize the full 85 percent 

efficiency of the ceramic trap in order to take full advantage 

of averaging. 
CHAPTER 2 

F.~ISSIONS !~PACTS 

T •. Introduction 

This chaote r· assesses the impact of the base and relaxed 

scenarios on total nationwide and urban diesel particulate 

emissions in iq9c; as comoared to those in 1980 and· 1986. 'T'he 

hase scenario assumes particulate standards of 0. 20 g/mi, O. 26 

q/mi, and 0.25 g/BRP~hr for liaht-duty diesel vehicles (LDDVs), 

1 iah t-nuty diesel trucks ( LDDTs l and heavy-duty diesel enq ine s 

(HDDEsl, resoectivelv. The relaxed scenario assumes 

non-technolooy forcino, non-trap particulate standards for all 

three vehicle classes (i.e., LDDVs and LDD'!'s will continue to 

emit' at current oarticulate levels, which are well below the 

current standard of 0.60 a/mi, while 4DDEs will emit at a level 

of O.fiO a/BHP-hr beainnina in 1988). Under both scenarios, the 

current NOx standards for LDDVs and LDDTs (i.e., 1. 5 and 2. 3 

a/mi, respectively) are assumed to remain in effect. The HDDE 

NOx stanrard is not. iClentified per se, but must be of such 

strinaency as to allow a non-trap particulate standard of 0.60 

a/BRO-hr to be met. · 

The first section of this chapter estimates 1980, 1986 and 

1995 particulate emission factors by vehicle type and model 

vear under the two control scenarios. The second section 

calculates nationwide and urban emissions for both control 

scenarios ov combinina these emission :actors with vehicle 

miles traveied (VMT), breakdowns by model year, diesel sales 

fractions, and nationwide and urban V~T projections. The third 

section compares some of these results with those of previous 

E'.CA analvses. 

II. Emission F3ctors 

. . - :·-.1-::--· ....... 

T!ie i~-i~-i~i ·- ~t~-P-- in de-term1nin·a··'.,'"· nati"on.wide "' ~nd urhan 

diesel partic'..llate emissions is to estimate emission factors 

for the vehicles of each model vear which comDrise the 1980, 

1986 and 1995 fleets. Generally soeakina, emission factors are 

the averaae emission rates (in a/m.i) that vehicles of a certain 

tyoe and aqe are expected to· emit durinq in-use operation. 

~mission factors usually· must be determined throuah in-use 

testinq because owner problems such as tampering, improper 

maintenance, and abuse can suhstantiallv chan~e actual emission 

levels from certification test levels: However, studies[l,21 

have shown that in-use oarticulate emissions from diesel 

enaines remain at certification test levels (with appropriate 

allowance made for ~ormal deterioration) throuahout the life of 

t!ie vehicle (i.e. , the owner-related problems mentioned above 

do not aocear to sianificantlv influence diesel oarticulate 

emissions): Therefore, t!ie diesel particulate emiss1on factors 
2-2 

estimated for this study are derived from current certification 

data in the case of LDDVs and LDOTs and from manufacturer and 

Aaencv test data in the case of PDDs. These data sources are 

fully described in Chapter 1. 

A. ~elaxed Scenario 

1. ~iaht~Dutv Diesel Vehicles and Liaht-Outv Diesel 

Trucks 

The projected post-1980 LDQV and LOOT emission factors 

under the relaxed scenario are easily determined, since it is 

assumed that these vehicles will continue to emit at their 

current levels. These current levels have already been 

determin~d in Cha~ter 1 and are simply the achievable half-life 

particulate standard levels shown in Table 1-2 of that 

chaoter. ~s discussed in 'Chapter 1, the achievable particulate 

standard level is the current certification test level 

multiplied hy the 50,000-mile c1eterioration factor (OF) and a 

10 percent safety margin (to account for production 

variability). Since the lifetime of a typical LDDV or LOOT 

islabout 100,000 miles, the half-life standard level can be 

viewed as the average emission rate over the life of the 

vehicle. That is, for the first 50,000 miles of its life, the 

•:eh ic le w i 11 emit be low the s tandar a level and for the second 

50,000 mile~ the ~e~~c~~ ~~l~_e~~t above the standard level. 

Weiahtinq these emission levels by the orojected 1983 

sales of each conf iauration yields fleet averaqe emission 

~actors of 0.27 a/mi for LDDVs and 0.28 a/;ni for LDDTs. 'rhese 

emission factors will be aoplied to each and everv model vear ' ·~· , rec{r .. ~:·s<~·n·tecf in~~~'"t.Re.·> T99s·-- ca-l"'endar:.:vear_:_ -~-fleet~·· - Strictiv··· .-=·~-

-~·-·· --~' ~oe~aiti no·~·~. t\·1 ·5· ~-'wou1d ~~not"·--s~·--·-tne'-'' <ca'se"" -·51 nC'e' 0 ra-e·? .. ~·v·eh~ic ie ;-:_~:.~·-: 

c;:eneraliy have hiqher emissions due to more neterioration and 

vice versa. However, the 50,000 mile deterioration factors for 

LDDVs anrl LDDTs are less than 1.1 on the a·:eraae (i.e., a 10 

oercent increase in 50,000 miles). Thus, while the emission 

factor for newer vehicles is slightly overestimateQ 

(deter i or at ion at th is po int is 1 es s than average) , the 

emission factor for older vehicles is sliahtly underestimated, 

and the net result is virtuallv the same as if each model 

year's vehicles were assianed. slightly different emission 

factors based on the deterioration occurring between individual 

model years. 
2-3 

Pre-1980 model year vehicles qenerally emitted hiaher 

levels of particulate than those of later years. Emission 

factors for these years were estimated from the historical 

emission levels and sales of these vehicles [ 31 and are shown 

below: 

~odel Year LDDV LDD'L' 

1980 0.5 o.s 

1Q79 0.8 0.9 

1978 0.7 0.9 

1975-77 o.s 0.5 

1971-74 o.s 

2 • }leavv-outv Diesels 

Estimatina emission factors for HDDF.:s is much more 

complicated than estimating emission factors for LDDVs and 

LDDTs, because HOOE emissions are measured in terms of grams 

per brake horsepower-hour (g/'BHP-hr) and not g/mi, as only the 

ena ine is tested and not the entire vehicle. Because vehicle 

emissions (in g/mi) can vary widely at a constant g/BHP-hr 

engine emission level, due to widely varying vehicle weights 

and sizes, the conversion of g/BHP-hr e'Tlission rates to g/mi 

equivalents in orc~er to obtain HOD emission factors is not a 

simple process. 

~he qeneral equation relating engine emission rate and 

vehicle emission rate is as follows: 

Vehicle.emi~sion factor =emission rate x fuel densitv (1) 

·· · 8SFc-~·x--· fuel'" economv. 

= a/BHP-hr x lb/aal 

lb/BHP-hr x m1le/qallon , 

= g/mile, 

where BSFC is the eno ine brake-soec if ic fue 1 consumption ana 

the fuel density for diesel fuel is 7.1 lb/aal. 

It was determined in Chapter 1 that the engine emission 

rate under the relaxed scenario would be 0.70 9/BHP-hr for 1987 

and earlier RDOs and 0.60 a/BHP-hr for 1988 and later HODEs. 

T~is leaves two factors still to be determined: vehicle fuel 

economy and enaine hrake-specific fuel consumption (BSFC). 

. . -.;..;.. •; :..-- ·. 
2-4 

a. Heavy-Duty Diesel Fuel Economv Estimates 

The fuel economy of heavy-duty diesel vehicles (HDDVs), 

like that of other vehicle types, is expected to increase in 

the future. This necessitates the use of projections and 

prevents the sole use of current HDDV fuel economy data. 

Present and future HHDV fuel economies were estimated for 

four vehicle subgroups based on an analysis of data from 

various sources. (This analysis is contained in Reference 4.) 

The HDDV subgroups are defined by gross vehicle weight ratina 

(f~VWR) as follows: 

Class IIB = 8,500 uo to 10,000 lbs. 

Classes III-V = 10,001 to 19,500 lbs. 

Class VI = lQ,501 to 26,000 lbs. 

Classes VII and VIII = 26,001 lbs. and uo. 

Current fuel economies for Classes IIB, III-V, and VI were 

derived from fuel consumption modeling results published by the 

Enerqv and Environmental Analysis, Inc. (EEA) for the U.S. 

Department of Enerqy. The EEA estimates were not used directly 

because the fuel consumotion values are based on total VMT and, 

hence, are more indicative of hiahway fuel consumption rather 

than urban fuel consumption. ~his latter oarameter is the most 

important here since the objective of this study is primarily 

to evaluate the environmental impact of particulte emissions in 

urban areas. Therefore, the EEA estimates for Classes II'B, 

III-V, and VI were reduced by 20 percent to represent urban 

fuel economies • 

. . ,,.,,"'.r~\~-· c:urrent f:iel __ economy f?r Class~s·~·VII-y~_II · w~s ~aken .·-· from~·-··test resul·t·s ~~collected ···by··· Southwest··· Research·--Tn·st·1tute····· • 

(SwRI) under contract to EPA. 'i'hese data were obtained using 

urban test cycles and, hence, are already representative of 

urban fuel consumotion. For comparison, the EEA value for 

Classes VII-VIII is aenerally about 25 percent higher than the 

SwRI estimate. 

Future fuel economy imμrovements for the four HDDV 

categories were derived from the above-mentioned EEA model inq 

results. As before, the values for Classes IIB, III-V, and VI 

were reduced by 20 percent to reflect urban fuel consumption. 

For ·classes VII-VIII, the EEA estimates still aooeared to 

remain more representative of highway fuel usage rather than 

urban fuel usage even if they were reduced by 20 percent. This 

is explained in that many of the expected fuel economy 

irnorovemen t tech no loa ies for these la rae r vehicles should be 

more beneficial during !iighway cruising than ·auring the 

stop-and-go driving which is characteristic of urba~ areas. To 

account for this difference, the largest overall increase of 
2-5 

the other. three cateqories (i.e., 

1980 to 1991) was also used to 

imorovement for category VII-VIII. 

15 percent improvement from 

represent the fuel economy 

The HDDV fuel economy estimates are shown in Table 2-1. 

b. μeavv-Dutv Diesel Brake-Soecific Fuel Consumption 

The second factor of the v·ehicle-emission eauation which 

needs to be estimated is HOOE brake-specific fuel consumption 

(BSFC). ~s with HDDV fuel economies, estimates of BSFC for the 

four weight categories were based on an analysis of data from 

various sources. (This analysis is contained in Reference 4.) 

The important f acto_r s which a re used to identify future f ue 1 

consumption improvements are the: 1) enq ine fue 1-sav i ng 

technologies, 2) urban fuel economy gains for each technology, 

and 3) market penetration of each technology. 

Table 2-2 presents ADDE BSFC by model year. 

c. qeavv-Dutv Diesel Fmission Factors 

Havinq estimated fuel economies and brake-specific fuel 

consumptions for each of the four HDD groups, the vehicle 

emission factors (g/mi) for each grou? oy model year were 

calculated using equation l and are shown in Table 2-3. 

These HDO emission factors, 1 i k e t~ose for LDDUs and 

LDDTs, all include half-life (or average) deterioration and the 

fact that newer vehicles have slightly lower emissions, and 

older vehicles slightly higher emissions, is ignored. This is 

.... aga.in .. verv ac.ceptabl~, since dete.riora~_iqn of ~DP p~rtic_ulaJ:.e., ....... . 

·.:' ~.emis·sio.n=s·.::should.:be ve.ry .. l.ow (abou.t ,15 ··pe:r·cent over t!ie··· life···,;q{~s.::o.:-v:s: 

th.e vehicle) • 

B. ~ase Scenaiio 

The base scenario differs from the relaxed scenario only 

in the fact that some vehicles in the base scenario are 

equipped with trap-oxidizers. Thus, excect for anv unique 

features of trap-oxidizers which affect in-use emissions, the 

:nethodoloav used here is the same as that described above for 

the relaxed scenario. That is, certification data with average 

deterioration and an approcriate safetv marain are assumed to 

adequately represent in-use emissions. (Emission factors for 

calendar years 1980 through 1986 do not need to be readdressed 

since the base-scenario standard does not take effect until 

1987 for LDDVs and LDDTs and 1988 for HDOVs.) 
2-15 

Table 2-1 

HDDV Fuel Economies (moq) 

~odel Year Class I!B Classes III-V Class VI Classes VII-VII! 

1995 13.l 10.6 1.6 5.12 

1994 13.l 10.4 7.6 5.10 

1993 13.0 10.2 7.6 5.09 

1992 13.0 10.l 7.6 5.07 

1991 13.0 9.9 7.6 5.06 

1990 13.0 9.8 7.6 5.04 

1989 12.8 9.7 7.5 4.98 

1988 12.7 9.7 7.5 4.92 

1987 12.5 9.6 7.4 4.85 

1986 12.3 9.6 7.4 4.79 

1985 12.2 9.5 7.4 4.73 

1984 12.0 9.4 7.3 4.67 

1983 11.8 9.4 7.2 4.62 ·-.:·-· ,. -. 

. . ...... ,. . . -:.r .. " ... -,.; -, -~ . - . ~19"'s·2 ··-·· _, - · -·-·- ··Ir. ··r· ·· · ---- · · 

1981 11. 6 

1980+ 11.4 

9.3 7.0 

9.2 7.0 

c - ., •••••• '"-'-: •• 4.~ 5 6 .. , . 

4.50 

4.45 
2-7 

Table 2-2 

HDDE Fuel Consumotions (lbm fuel/BHP-hr) 

Model Year Class !!B Classes !!!-V Class VI Classes VII-VIII 

1995 0.41 0.39 0.41 0.39 

1994 I) • 4 1 0. 39 0.41 0.39 

1993 0.41 (). 40 0.41 0~39 

1992 0.41 I) ."4 0 0.41 0.39 

1991 0.41 0.41 0.41 0.39 

1990 ,, . 4 1 0.41 I) • 4 1 0. 3 9 

1989 0.42 0.42 0.41 0.40 

1988 0.42 0.42 o.~1 I) • 4 0 

1987 0.42 0.42 0.42 0.40 

1986 () . 4 2 I) • 4 2 0.42 0.41 

1985 0.42 0.42 0.42 0.41 

1984 0.42 I) • 4 2 0.42 0.42 

.. 1983 0.42 . 0. 4.2 .r 1 • . . ., --· , .. .0.43. 0.42 ····~··· ...... ~.- -·.;..:·~-.; -~ c.·:~:~-;-- .. ... :~·r::. :·. ~ -~- "'::,_;· : ... ,, r l: E_': }":,. ~· .... - .~· '"'-' . .. .. . r.:. ::. ;.:·· '•.:.· -.· . ....... ~·.')· '"! ·-:-:.:; "":\ • ,.: j"' •· ~ ... . ~ • !·•1 ... •. '" • •• l· .. · .• · ........ 

1982 0.42 0.42 f) • 4 3 0.42 

1981 0.42 0.43 0.43 0. 4 3 

1980+ 0.43 0.43 0.43 0.43 
2-8 

Table 2-3 

Relaxed Scenario HDDV Emission Factors (a/mi) 

Model Year Class I!B Classes III-V Class VI Classes VII-VIII 

1995 

1994 

1993 

1992 . 

1991 

1990 

1989 

1988 

1987 

1986 

1°98 5 

1984 

•• ·- ,L.' ·-· •. -· •;.. •.••• 

0.80 

0.80 

(). 80 

0. 80- .. 

(). 80 

0.80 

0.80 

0.81 

0.95 

0.97 

0.97 

0.98 

0.99 

l.04 l. 38 

l. 04 1.38 

l. 05 1. 38 

1. 05 - 1. 38 

1. 05 l. 38 

1. 06 1. 38 

1. 06 1. 38 

1.06 1. 38 

1. 24 1. 61 

1.24 1. 51 

1.24 1. 111 

1.25 1. 61 

1. 25 1. 62 

2.13 

2.14 

2. 14 

2.14 

2.15 

2.15 

2.16 

2.16 

2.53 

2.53 

2.55 

2.56 

2. :S6 - .. -. . . . .- .. :.f ... ~--- •.• •!:. :.. ... • : . . -- ---.· ...... 

:-.:_.:':~_;t.:.~:.."£.::. .;~;i::-~ .. ;.: ~- ;::1:9'82"-:" · "'! t -_;. '" '·r~·db'- =·. ··:.~- .-::-" y·. ·2 5 ::·· ·"-·~ ":::: ·_:·:'.'~. :· t • 61:::c .:::·!: ·.--: .. ~.c :-?-2~~-5'·8 ~ ~:!r- · .... ~·;: ~"-·:--.. 

1. 00 1. 25 1. 65 2.59 

1980+ 1.01 1. 26 1. 65 2.60 
2-9 

The. one feature of trap-oxidizers which may affect this 

relationship between certification and in-use emissions ·is the 

possibility of trao failure. '!'rap-oxidizer systems are not 

currently being used on any vehicles, and therefore, there are 

no data on their reliability in-use. T'...imited . data on 

trap-oxidizer system durability has been generated by 

experimental testing pro9rams. [51 These programs have 

demonstrated that traps can physically undergo repeated 

reaeneration cycles over 50,000 miles of vehicle ooeration and 

still maintain their initial trapping efficiencies. However, 

these test oroarams involved only a few vehicles and somewhat 

controlled operating conditions. It is possible that when put 

into' qeneral use, some failures of trap-ox~dizer systems will 

occur. 

The reasons for failure of a trap-oxidizer system can be 

divided into two general categories: 1) failure of the 

electronic control system used to reaenerate the trao, and 2) 

physical failure of the trap due to unforeseen ·oper~tinq 

conditions. ~lectronic control ·systems consistinq of 

microprocessors and central processing uni ts (CPUs) have come 

into widespread use on liqht-duty vehicles since 1980. '!'hese 

control systems, used in conjunct ion with three-way catalysts, 

are necessary to attain the 1981 emission standards for many 

vehicles. Recent testing of in-use vehicles by EPA's Emission 

Factor Testing Proqram[61 has generated data on the failure 

rate of these electronic control systems. That data indicates 

that 1.5 to 2.0 percent of 1-year old liaht-duty vehicles of 

1981-82 vintage are gross emitters of HC and CO. Since it is 

reasonahle to assume that the reason for the aross emissions is 

failure of the electronic control system, it. can he concluded 

._.that. th,e .. fail.u.re. r.ate ... fo_r .. elect:;ronic .. cont.r,ol systems"' for .these 

model year vehicles was about l.S· to 2.0 percent per year. -.:] .. t;~:-. ·.·':~'"· 

should be noted. that these results are based on a limited 

number of vehicle tests and could be subject to change in the 

fu.ture. 

This failure rate shoulci be adjusted to account for the 

fact that this electronic control technology is relatively new 

3nd that, for the purposes of this study, trap-oxidizer systems 

will not be required before 1987. The industry has five more 

years to reduce the failure rate of electronic control 

systems. Therefore, the failure rate for 1987 and later 

elect:;ronic control svstems used on trap-oxidizers is estimated 

to be 1.0 percent per year. 

'l'he other general cateqorv of trap-oxidizer system 

failure, as mentioned above, is the occurance of unforeseen 

operating conditions. Manufacturers will desian trap-oxidizer 

svstems to withstand almost every in-use condition they can 

foresee. qowever, it is still possible that certain ooeratinq 

conditions will occur which prevent proper regeneration of the 
2-10 

trap, thus, leading to eventual trap failure. Therefore, a 

failure rate of 0.5 percent per year will be used in this 

analysis for this second type of trap-oxidizer system failure. 

Add inq the electronic control sys tern failure rate to the 

unforeseen ooeratino conditions failure rate yields· an overall. 

failure rate of l. 5 percent per year for LDDVs with traps. 

This overall failure rate will also b~ used f6r LDD~s and 

MDV/LHDVs because their annual mileaqes and lifetimes are 

similar to those for GDDVs. qoovs, however, while having 

approximately the same lifetime as these other vehicles, are 

driven, on the averaqe, suhstantially more miles per year. 

Therefore, the 1.5 percent per year failure rate was adjustet1 

for HHDVs to reflect the oreater (factor of four) annual number 

of miles by these vehicles. In doing this, the 1.0 percent per 

year electronic fai1ure rate was held constant since these 

types of failures were assumed to be primarily due to factors 

such as time and transients in enqine compartment temperature, 

which here depend more on time than annual vehicle mileage. 

The 0.5 percent oer year failure rate due to the occurence of 

unforeseen operating conditions, on the other hand, was assumed 

to be oar t ia l ly dependent on annual mi le age and was cioubled. 

·Thus, the trap failure rate used for HDDVs was 2.0 percent per 

year • 

. f.1aving determined the trap-oxidizer system failure rates 

for--the different vehicle types, these failure rates can be 

combined with the basic methodology used to estimate the 

emission factors under the relaxed scenario to estimate 

emission factors under the base scenario. The results of this 

combination are shown in Table 2-4. 

'"·.·~~·~·:_··.~;~ .. -~~:--:~,-~~~~~.:.,~.-~~ ... ;;_,·~;~~ - 7~--~-~--·~~·~~;~- ·. ->~.-·:~·:.·--· -~ ~~'.- . -- . - ·.:-.~ .. -. _-.... ·. ~_ .. · ·~·- -- ..... -·---_- ~~- -~ .... :·;. ··.·: ...... -· , __ ..._;"" ·-""·~-'-"·":·-"'--· .:::.:.-0 .. :...h.e_ ... _ 1.9:.. .. .5._,_e;m.1,s.s i o:n.:.-~.fa.~·tOJ:'z.S.,·~·_ f o.~-:c.:-LP;QY."5-~.,~ 9.!:'d. "· LJ?Q~ $, .-: .. .?"~·'·:-.:i!l.29~J::-.~.:.:~ __ :; 

ye a r-s 19-7 8 th rough 19 8 6 and f o r P. DD s from 1 9 7 8 th r o ugh 19 S 7 ~ r e . 

the same ~s those under the relaxed scenario. This occurs ~ecause the more stringent ~articulate stannards of the base 

scenario no not become effective until 1987 in the case of 

LDDVs and LOOTS and 198A in the case of HODS. 

When the new standards do become effective, it is aqain 

assumed that vehicles will emit, on the averaqe, at their 

applicable standard levels, ~xcept for the ef~ect of trap 

failure. These applicable standard levels are 0.20 g/mi for 

LDDVs, 0.26 g/mi for ~DD~s, and a 60 percent reduction from the 

relaxed-scenario levels identified in the previous section for 

HDDs. ~o these levels must be added the effect of trap 

failure. ~his is done according to the following equation: -

~odel Year Emission Factor = Standard Level + (Vehicle 

Age) x (Trap Failure Rate) x (Fraction of Vehicles with 

Traps) x {Difference between Non-trap Emissions and 

Standard Level) 
2-11 

Table 2-4 

Base Scenario Emission Factors (a/mi) 

HOV HOV 

Vehicle Class Classes 

Model Year LDDV LDDT rra rrr-v LHDV ~HDV 

1995 .20 .26 0.34 0.44 0.58 0.90 

1994 .20 .26 0.34 0.45 0.59 0.93 

1993 .20 .26 0.35 0.46 0.60 0.95 

1992 .20 .26 0.36 0.47 0.62 0.98 

1991 .20 .26 0.36 0.48 0.63 1.01 

1990 .20 .26 0.37 0.49 I). 64 l. 03 

1989 .20 .26 I) • 3 8 a.so 0.65 1.06 

198A* .20 • 2 Ii 0.39 0.51 . 0. 67 l. 09 

1987** .20 .26 0 • 9 5 1.24 l. 61 2.53 

1986 .27 .28 0.97 1. 24 1. 61 2.53 

1985 .27 .28 0.97 1.24 1. 61 2.55 

1984 .27 .28 0. 9 8 1. 2 5 l. 62 2.56 

198l' ·~ .. ' • 2 7 . •. ·: . .:;·:·20 . 0. 99.: 1~25 ·~ ": l :.·6 2 ... 2". '5 6 u. ·"" •'" • ..t •• 

1982 .27 .28 1. 00 1. 25 1. 63 2.58 

19Rl .27 .28 1. 00 1. 25 1. 65 2.59 

1980 .so . so 1.01 1. '2 6 1. 65 2.60 

1979 .80 .90 1. 01 1. 26 l. 65 2.60 

1978+ .70 .90 1.01 1. 26 l. 65 2.60 

* Base scenario becomes effective for HODs. 

** Base scenario becomes effective for LDDVs and LDDTs. 
2-12 

Some, of the terms in the above equation deserve some 

elaboration. Vehicle age is assumed to 0.5 years for 1995. model 

vear vehicles and one year greater for each preced in9 model 

year. Trap failure rate is 1.5 percent for LOOVs, LOOTS and 

MDV/LHDVs and 2.0 percent for pqovs. The fraction ·of vehicles 

with traps is included in the above equation because the trap 

failure rate should only be applied to vehicles with traps. 

This figure is _0.223 for LOOVs, 0.076 for LD0'1's and 1.00 for 

all HODVs. 

The difference between non-trap emissions and standard 

leve 1, is included to account for the fact that the vehicle 

emissions should simoly revert back to their non-trao levels if 

the trap should fail·. The standard -level is subtrac.ted because 

emissions up to this level have alreadv been taken into account 

by the first term on the riaht hand side of the equation 

(standard level). tn the case of RDDVs, the non-trap emissions 

are simply those occurring under the relaxed scenario, because 

all qnovs were assumed in Chapter 1 to emit at the same level 

(i.e., the non-trap level of trap-equipped vehicles is the same 

as the emission level of vehicles without traos). However, a 

dis tr i but ion of vehicle emissions . ..,.as determined in Chapter l 

for LDDVs and LDDTs and traps were placed on the hiqhest 

emit t in g v eh i c 1 es f i r st • Thus , the 'ion - trap 1eve1 s · for 

trap-equipped LDOVs an.a LDOTs (Cl.39 ~/;ni and 0.33 a/mi, 

respectively) are higher - than the non-trap levels of the 

rel-axe<i scenarios- (0.2-7- .g/mi. and.0.28 q/mi, respectively). 

rrr. Nationwide and Urban Smissions 

The next step in de ter·mi n ing nationwide and urban . . . b' . " d 1 " . . t: ,. ·~ ~:1'}~.~;;?:.1~--'.~.1-s"'- to,,,:.c_o_m._1.ne_:::"t~e ._ -~O- .e. - year_._, __ .,_,~m.1ss10.n,_. !.~ctg,~~---j'"''"'' -· --~ · g'e·n e·r-a-t- e{1-.~1~n- th e.-.:..p.r..e.v.1~0.u:s:.-.s'.e.c .ti.on:" .7f.o.r .. ::1e ac h;:c:-Y'e h l c 1 _e _t;ypg - ~ n t_ C:h,--.~ ·;;,,._7r.~.~~--"' 

single, weighted calendar-year emission factor for each vehicle 

tyoe. This is done by multiolyina each model year's emission 

factor by that model year's fraction of calendar-year V~T and 

the diesel sales fraction for .that model year, and then 

summminc:i across all model years. The result is an emission 

factor that is appropriately weighted by both the number of 

diesels on the road, relative to total vehicles, and by their 

age. rn other words, the 1995 weiohted emission factor is now 

on a total (i.e., qasoline and diesel combined} VMT basis for 

that vehicle type. 

'!'he 1995 distributions of VMT by model year [71 are shown 

in Table 2-5 for LDVs, LDTs, and HDVs. It should be noted that 

the VMT breakdown shown for ~DV Classes !IB, !II-V, and VI is 

that given in the reference for gasoline-fueled HDVs and the 

VMT breakdown shown for HDV Classes VII-VIII is that· for 

diesel-powered HDVs. This is appropriate because at the time 

the referenced study was performed, the qreat ~ajority of 

gasoline-fueled HDVs were in Classes IIB-VI and nearly· all HODs 
2-13 

Table 2-5 

1995 Calendar Year Fleet-Wide Average 

V~T Fraction Distribution hv Model Year 

Classes ·HDV 

IIB, III-V* Classes 

Model Year LDV LDT Class V! VII-VIII 

,~ ............ 

* 

1995 .091 .159 .201 . 24 7 

1994 .124 .137 .161 .188 

1993 .1na .108 .124• .102 

1992 .080 .072 .084 .058 

1991 .100 .096 .090 .093 

1990 .107 .098 .083 .080 

1989 .088 .068 .059 .056 

1988 .067 .050 .041 .038 

lq97 .059 .035 .029 .029 

1986 .050 .035 .028 .028 

1985 . (') 3 8 . 032 .024 .020 

1984 .026 .021 .017 .015 ··•1 .... . • ' -· ~ •.. ...,.. ··- ....... • .•• -· • " .'1 ~ .• : • •· • • "•:. •' •• ·~· .. I • -:· • ._.. .::... .~· ... . - .. .. .. ·"' - . '. . -- . 1983 .021 • 0·22 .015 . ins .. 

1982 .015 .019 .012 .011 

1981 .009 .014 .009 • (')0 7 

1980 .006 .011 .007 .005 

1979 .003 .007 .005 .003 

1978 .001 .005 .003 .001 

These VMT fractions are used for each HOV subgroup 

separately. 
2-14 

were in Classes VII and VIII. However, the use of the 

historical Class IIB-VI breakdown here does assume that the 

dieselization of this class will not alter this breakdown. 

The diesel sales fractions for each model year are shown 

in Table 2-6 for LDVs and LDTs, and in Table 2-7 for HDVs. Two 

sets of projections are used in this study. The first is a 

"best estimate" projection and is based on. a continuation of 

present . conditions, including the absence of a major oil 

crisis. This results in moderate growth of diesel sales. The 

second set is a "worst case" projection, which could be 

realized if another oil crisis were to occur. liere, the rate 

of dies.el sales --is substantially· hiaher· than under the·· best 

estimate projections. The term "worst case" refers to the 

degree of environmental impact which would occur due to diesel 

particulate emissions. 

Regarding the best estimate diesel sales fractions, 

historical diesel and total sales data were used for model 

years 1961-82. The LD sales fractions for model years 1990 

throuqh 1995 are those determined in a study[8] for EPA by Jack 

Faucett ~ssociates which investiqated the impact on diesel 

oenetration in the LDV and LDT markets of diesel oarticulate 

standards. The LDV and LDT diesel sales fractions· for model 

years 1983-89 were obtained by linearly interpolating between 

the fioures for lq82 and 1990. The 1985, 1990, and 1995 Hnv 

sales fractions were derived from projections made by Data 

Resources Inc., [91 with the in-between years aaain being 

obtained by linear interpolation. 

. . . .. ~.ePar d.i no .. _ .~.h.e .. wo_r ,s_t .c:.a,s.e~:.. ~:· sa 1 ~ s =·- .f r.ac_t i_o.n~s, in-ho~u se _ .. ,_:_.::'.est ima:t.-e s were. :used. to ,,r·epr.e sen t·.·~·w,ha t is.: .cons ide-r-ed .to. b.e. :the. , .. , 

rnaxi:num diesel ;>enetration in this timeframe. r:or :nodel years 

1961-83, the diesel sales fractions are, or course, identical 

to the best P.stimate diesel sales fractions because they are 

based on historical data. 

For LDVs, a maximum diesel penetration rate for the 199 S 

model year was projected to be 30 percent. It was also thought 

that most of the increase in diesel penetration between 1984 

and 1995 would occur in the first half of this time span. 

T~us, the LDV penetration rate rises by three percentage points 

per year from 1984 through 1990 and after which rises by only 

one ~ercentage ooint per year through 1995. 

For LDTs, a maximum diesel ?enetration rate of 60 percent 

was projected for 1995. Unlike LDVs, however, the increase in· 

LDT dieselization is likely to be more consistent with time, 

due to the fact that significant dieselization is already 

occurring under the best estimate projections. Therefore, a 

constant increase of four percentage ~oints cer year was 

projected from 1985 through 1995. 
.. ; .... :".' .. ·.·..;: : ·-

2-15 

Table 2-6 

Diesel Fraction of Total tiqht-Dutv Vehicle Sales 

~odel Year 

1995 

1994 

1993 

199'2 

1991 

1990 

-1-99·9 -

1988 

1987 

1986 

1985 

1984 

-- l,983_ 

1982 

1981 

1980 

1979 

1978 

1977 

1976 

1975 

1974 

1973 

1972 

1g71 

.: -: -_.: .:'.l.~9:1·0·+·-.:- ~. · .. '--· .. _ · · • · 

Best ::stimate 

LDDV LOOT 

.115 

.115 

.114 

.114 

.113 

.113 

• 100--

• 090 

.080 

.073 

.066 

.060 

.053 

.046 

.061 

.034 

.028 

.009 

.004 

.003 

.003 

.003 

.003 

.003 

.003 

·:.·ooo··. 

.339 

.330 

.321 

.312 

.303 

.294 

.27 

.240 

.210 

.180 

.160 

.130 

.100 

.080 

.060 

.034 

.028 

.009 

.005 

.003 

.po2 

.000 

.coo 

.000 

. noo 

·~ooo· ·· 

Worst 'Estimate 

LDDV LOOT 

.300 

.290 

.280 

.270 

• 2fi0 

.250 

.220 

.190 

.160 

.130 

.100 

.070 

.053 

.046 

.061 

.034 

.028 

.009 

.004 

.003 

.003 

.003 

.003 

.003 

• /) 0 3 

· ·· ·~·ooo 

.600 

.560 

.520 

.480 

.440 

.400 

.360 

.320 

.280 

.240 

.200 

.150 

.100 

.080 

.060 

.034 

.028 

.009 

.005 

.003 

.002 

.000 

.000 

.000 

.000 

~ 00 0. '. ~· . 
2-16 

Table 2-7 

Diesel Fraction of Total ?eavy-Duti Vehicle Sales 

Best Estimate Worst Estimate 

Model Class Classes Class Classes Class Classes Class Classes 

Year IIB III-V. VI VII-VII! IIB II!-V ~n VII-VIII 

1995 .371 .476 .669 .983 .895 l. 000 l. 000 1.000 

1994 .357 .463 . 64 5 .980 .841 l. 000 1.000 l. 000 

1993 .343 .449 .621 .978 .789 l. 000 1. 000 1. 000 

1992 .329 .436 .598 .975 .741 .949 1.000 1. 000 

1991 .315 .422 .574 .973 .694 • 910 1.000 l. 000 

1990 .301 .409 .550 .970 .648 .864 l. 000 l. 000 

1989 .287 .396 .526 .967 .546 .764 1.000 l. 000 

1988 .273 .382 .502 .965 .546 .764 1.000 1. 000 

1987 .259 .369 .479 .962 .503 .716 .929 l.000 

1986 . 2 4 c; .355 .455 .960 .422 .• 612 .784 1.000 

1985 .231 . 342 .431 .957 ·• 3 4 4 . - .510 .642 .949 

1984 .179 .264 .369 .947 • 2 5li .377 .513 .958 

1983 .126 .186 .286 .937 .126 .186 .286 .937 

1982 .074 .108 .214 .928 .074 .108 .214 .928 

1981 .037 .054 .164 .918 .037 .054 .164 .918 

1980 .000 • IJOO .114 .91 .000 .000 .114 .91 

1979 .000 .ooo .114 .89 .ooo .000 .114 .89 

lcn9 .ooo .000 .078 .88 .000 . 0 () 0 .078 .88 

. 1977 .000 .ooo .070 .85 .000 .000 .070 .85 

1976 . 000 .000 .042 .83 .000 .!JOO . '14 2 .83 

1975 .000 .004 .032 .73 .000 .004 .032 • 7 3 

1974 .ooo . 1')01 .016 .77 .000 .001 .rn6 .77 

··:1973· ·; oco· · · ·--. 0 0-3 .016 ~78· • 000-. .003 .•. o 16 : • 7 8 ., ~·· ...... :- -:: · i-cn·2 .ooo : .. 0 2 0 ..• () 16 .76 -:oo·o . ·O· 2 0 .. : · · ' -~ . -~ 0 l-fr , .. 7 6 .~ 

1971 .000 .020 .015 .75 .000 .020 .016 • 7 s 

1970 .000 • ')2 0 . '116 .75 .000 .020 • 1)16 .75 

1969+ .ooo • 00() .000 .75 .000 .000 .000 .75 
2-17 

For the four classes of HDVs, the worst case dieselization 

rates we're derived by estimating the year that · total 

dieselization would occur and then by linear interpolation to 

historic levels. These years were ·1997 for Class IIb, 1993 for 

Classes III-V, 1988 for Class VI, and 1986 for Classes VII-VIII. 

The weighted emission factors (g/mi) for each calendar 

year, vehicle type, control scenario, and diesel sales scenario 

a r e shown i n Tab le 2 - 8 , a long w i th e s t i ma t e s o f to ta l VMT 

(oasoline plus diesel) and the urban percent of VM'1:' for each 

vehicle type. 

·Estimates qf total nationwide V~T for the years 1980, 

19.86, -and 1996 were obtained from an EEA Quarterly Report. [101- · 

The urban/rural S?lits were obtained from U.S. Federal qighway 

Administration data. [llJ It should be noted that this 

ur ban/rur a 1 s;>l it data for HDVs was · not broken according to 

vehicle size but by generic type (i.e., bus, single-unit truck, 

tractor-trailer combination). Tt was assumed that buses and 

single-unit trucks were Classes IIB-VI vehicles and that 

tractor-trailers were Class V!I and VIII vehicles. 

Nationwide emission estimates are obtained by simply 

multiolvinq the weiqhted emission factors by VMT. rJrban 

emissions are obtained by multiplying the nationwide emissions 

estimates by the urban VMT fraction. '1'hese figures are shown 

in Tables 2-9 and 2-10. It should be noted that the· emission 

estimates in these tables for BDDV Classes IIB, III-V, ~nd V! 

have ~een combined into a single category labelled medium-dutv 

veh ic le/l i oh t heavv-du ty vehicle ( ~DV /LHDV) to ease the 

:oresentation of the results. The subsequent discussion will 

focus on t~e urban emission results of Table 2-10 as these are 

.. "the .. in"<55t""···?ertfnen"t··:,~.ith. resp·e'ct ._,,.'to·· human· ~~J?_osur·e· t·o ... dies.~.l .. · 

?articulate emiss'"fons~·-····· 

Table 2-10 has been arranged to depict a number of 

effects. One, projections for calendar years 1980, 1986, and 

1<195 have been placed side-by-side to allow easy comparison. 

Two, the effects of both the relaxed and base scenarios are 

shown in 1995 to deoict the effect of control. Because the 

control of LDDVs and ·LDDTs provides so little control relative 

to μoov control, a modified base scenario has been added where 

only ~DDV emissions are controlled. Three, an attempt has been 

made to de9ict the causes of the increases in total 1Jrban 

e!llissions between 1980 and future years. Beside each emission 

esti~ate for 1986 and 1995 is a percentage which indicates that 

vehicle class' contribution to the overall increase in urban 

emissions between 1980 and that year. ~or example, ~DOV 

emissions are 24,600 metric tons per year in 1995 under- the 

best estimate, relaxed scenario. This is an increas~ of 20,700 

metric tons per year from the 1980 level. T~e 30 percent 

... ····• ...... · 
2-18 

Table 2-8 

Weiqhted Emission Factors and Projected 'VMI' 

t..Jeiahted Emission Factor (a/mi) 

Calendar Year 1980: 

All Scenarios 

Calendar Year 1986: 

Best Estimate Diesel Sales 

Worst Case Diesel Sales 

Calendar Year 1995: 

Best F.sti:nate Diesel Sales 

Relaxed Scenario 

Base Scenario 

Worst Case Diesel Sales 

Relaxed Scenario 

3ase Scenario 

Class Classes Class Classes 

!Dr !IB I!I-V VI VII-VIII 

0.0059 0.0075 0.000 0.0027 0.11 

0.014 0.027 0.13 

0.016 0.032 0.19 

0.027 0.076 0.25 

0.021 0.071 0.12 

0.061 0.12 

.0.046 0.11 

0.56 

0.27 

0.24 

0.36 

0.44 

0.22 

0.91 

0.44 

0.46 

0.66 

0.80 

0.40 

1.30 

0.65 

2.19 

2.37 

2.41 

2 .13 

1.14 

2.18 

1.17 

' .. ,. 9 . . . ...... .... -· --· .. . ..... ·- . ?ro;ected vm no . !'liles) : .(10] ... •n ~··~ ~· .. -·•· - .-•- ·- -• -1· •· • ' ~ -·-· ... --

1980 

1986 

1995 

Urban Percent 

of VMl' (all vears) £111 

.. . ··- - ~ -

1, 118 209 

1,220 241 

1,540 330 

59 49 

13 .8 

24.4 

40.5 

49 

6.63 

4.56 

4.69 

49 

lA.4 

12.3 

9.97 

49 

;:-,.·. ··~,:..~ ........ -~,'j __ 

73.8 

85. 7 

117.9 

27 
LDDV 

LOOT 

MDV/LHDV 

HHDV 

.Total 

LDDV 

LOOT 

~DV/LHP"-~ 

!1HDV 

Total 

2-19 

Table 2-9 

Nationwide Diesel Particulate Emissions 

(metric tons cer vear) 

Best Estimate Diesel Sales 

1980 

l;,500 

1,900 

2,000 

149,000 

159,400 

1986 

lli,400 

J, 200 

6,500 

200,000 

230,100 

Relaxed 

Scenario 

41,500 

2 5, 000_ 

19,300 

251,000 

336,800 

Worst Case Diesel Sales 

1980 

6,500 

1,900 

..... , .. 2, 0.0.0 

149,000 

159,400 

1986 

19,900 

8,400 

1.5.,. S.0.0 

202,000 

245,800 

:Ji: laxed· 

Scenario 

93,100 

38,500 

... J.8.,, 3 0 () 

257,000 

421i,900 

1995 

Base 

Scenario 

32,200 

23,600 

9,600 

134,000 

199,400 

1995 

Base 

Scenario 

71,400 

36,000 

lA,600 

139,000 

265,000 
1980 

LWJ 3,900 

LDOI' 900 

2-20 

Table 2-10 

Urban Diesel Particulate Emissions 

(:netric tons oer vear) 

Best Estimate Diesel Sales 

1986 

Relaxed 

Scenario· 

1995 

Base 

Scenario 

9,700 (24%)* 24,~00 (30%) 19,100 (60%) 

3,500 (11%) 12,200 (17%) 11,500 (41%) 

1995 

Base Scenario 

Q1lv HDD Control 

24,600 (64~) 

12,200 (36%) 

~/LlIDJ 1,000 3,200 (9%) 9,400 (12%) 4,700 (14%} 4,700 (12~) 

HHVJ 40,000 53,700 (56%) 67,nOO (41%) 36,100 (-15%) 36,100 (-12%) 

Total 45,800 70,100 113,800 71,400 77,600 

LOOI 

'I'otal 

* 

1980 

3,900 

Worst Case Diesel Sales 

1986 

11,800 (20) 

Relaxed 

Scenario 

1995 

Base 

Scenario 

55,300 (44%) 42,400 (64%) 

1995 

Base Scenario 

C'r\lv U.OD Control 

55,300 (69%) 

.·· 900_ ... 4,.100 (10~) -'·-·18,800 .. _{16%) .17,_600 (2.8%) ···-··· 18.,.80.0 ... (.23%) 

1,000 

40,000 

45,800 

... ·.· . ,.._ ...• -- -· .. , .T .- ·;-·:.. -

7,600 (21%) 18,700 (15~) 9,100 (13~) 

54,500.(45%} '69,200 (25%) 37,000 (-5%} 

78,000 162,000 106,100 

9, 100 (lHl 

37,000 (-4%) 

120,400 

Figures in carentheses depict each vehicle class contribution to the overall 

emissions increase over 1980 emissions (in i:;ercent}. 'ttle sum of ~~e 

?ercentaqes for the four classes is 100 ;:iercent. 
2-21 

fioure beside the 24,600 metric ton per year estimate indicates 

that the '20,700 metric ton per year increase is 30 percent of 

the· total increase in urban emissions between 1980 and 1995, 

69,300 metric tons per year. 

Con c e r n i n g the act u a 1 f i g u res i n Tab le 2 - 1 O ,· i t ca n be 

seen that urban emissions increase between 1980 and 1995 

r eoard less of the scenario chosen. . 'l'he increase is smallest 

for the best estimate, _base scenario (57 percent) and largest 

for the worst case, relaxed scenario -(257 percent). As can be 

seen from the figures in par en theses, the largest con tr ibu tor 

to these incr·eases are LDDVs. i::rnovs contribute to the 

. increases under the relaxed scenarios, but actually serve to 

·mitigate such increases. under the relaxed scenarios •.. a.lso, 

while LDDVs, and LDDTs in some cases, produce the largest 

emission increases, their control under the hase scenario has 

the least effect. LDDV emissions are onlv reduced 22 oercent 

and LDDT emissions only 6 percent, as opposed to MDV /LHDV and 

HHDV emission reductions of about 50 percent. Finally, the 

effect of only controllinq HOD emissions and avoiding further 

control of LDDV and LDDT emissions ·is small. Overall urban 

emissions only increase about 10-15 percent. 

A final pertinent aspect of the urban emission estimates 

of Table 2-10 is the relative contribution of each vehicle type 

to overall urban emissions. Table 2-11 shows the fraction of 

total urban emissions in each year being emitted by each 

vehicle class. As can be seen, the relative contributions vary 

depend i nq on which situation is examined. One oener al 

observation is that, despite its low urban VMT fraction, HHDVs 

are still !'najor contributors to urban emissions regardless of 

diesel sales scenario (e.g., 31 to 45 percent under the relaxed -.. ~ .. -.-~ .. scenar·io)·~·.· -.. ,_""""'•~ ·-.. ,,,-·;;;.~;·~.,. .. .... ...... ..,. .. .. . . ... '"""r.:.-••;;,_, .. ,X',"'" 

: . . ~ - .... .... ! • • - . b :.. .... ,.!"'". 

rv. Comnarison of Results with Previous Studies 

It is also oertinent to comoare the results 

to the project ions of urban d iese 1 part icu late 

previous studies. Th is was done for two cases: 

and worst case diesel sales. 

of Table 2-10 

emissions of 

best estimate 

The R.egu la tory Ana 1 ys is which accompanied the 19 8 2 

light-duty diesel particulate regulation[3] estimated 

nationwide light-duty diesel particulates in the year 1990. 

'!'wo scenarios were analyzed: 1) an uncontrolled scenario where 

light-duty diesel vehicles and trucks were projected to emit 

1.0 g/mi particulate, and 2) a controlled scenario with a 0.60 

g/~i standard for 1982-84 and a 0.2 q/mi standard for 1985 and 

beyond (0.26 g/mi for light trucks). (This controlled scenario 
1980 

LDDV 9~ 

LDDT 2% 

,,,DV/LHDV 2% 

HHDV 87, --

Total 100% 

1980 

LDDV 

LDDT 2% 

HHDV 8 7% 

Total 100% 

2-22 

Table 2-11 

Relative Contribution of 

Urban Emissions (oercent) 

Best ~stimate Diesel Sales 

1995 

·Relaxed Base 

1986 Scenario Scenario 

14% 2 2% 26% 

5% 11% 16% 

5% 8% 7% 

7 Ii ~ 59% 51~ 

100% 100% 100% 

worst Case Diesel Sales 

1986 

15% 

5% 

1995 

Relaxed Base 

Scenario Scenario 

34% 40% 

12% 17% 

1995 

Base Scenario 

Onlv HDD Control 

32% 

16% 

6% 

41i% 

100% 

Base Scenario 

Only HDD Control 

46~ 

16% -. ~-· ...,. ~ - - ---- ' ... ;:;._ " • ~.: t: ~- "'- - .. - ......... ~~·-· ... -._-· ... _ ... . 

70% 4 3% 

100% 100% 

35% 

100% 

7% 

31~ 

100% 
2-23 

is the same as the base scenario of this study, except here the 

1985 standards have been delayed to 1987.) A range of 

potential diesel penetrations was examined by applyinq a +25 

percent bracket around a "best estimate" diesel saies 

scenario. The LOOY NOx stannard was presumed to be l. O g/mi 

(part of the reason for the high uncontrolled ·particulate 

emission factor). 

This 1979 analvsis estimated that 1990 urban emissions for 

LOOVs and LOOTS would be 84,000-141,000 metric tons per year 

under the uncontrolled scenario and 22,000-37,000 metric tons 

per year under the controlled scenario. Extrapolating that 

same methodology to 1995 (i.e., continued diesel oenetration 

in to the in-use fleet and sl igh tl y increased total VMT) , urban 

emissions would have been projected to be 112,000-190,000 

metric tons per year (uncontrolled) and 30,000-50,000 metric 

tons per year (controlled). 

As shown in Table 2-10, best estimate, urban emissions for 

LDDVs and LDDTs for both the relaxed and base scenarios fall 

within the previous estimates for the controlled scenario: both 

scenarios resulting in emissions well below that for the 

previous uncontrolled scenario.* Worst case. urban emissions 

under the relaxed scenario are greater than the upper limit for 

the previous controlled scenario, but still well below that for 

the uncontrolled scenario. Worst case emissions under the base 

scenario are essentially equal to the upper limit of the 

previous controlled scenario. 

Movinq 

accom9anying 

to HDOVs, the Draft ?eaulatory Analysis 

the heavy-duty diesel particulate NPRM estimated 

· * · .. ·The great .. :najority of the. difference· between the est-imat-es ······~ 

.. for · the r·elaxed · scenar .. io of th fs · study a·na: ·the 

uncontrolled scenario of the previous study is due to the 

difference in projected emission factors. ~he previous 

study projected a uncontrolled particulate emission factor 

of 1.0 g/mi while this study has estimated the current 

non-tiap emission factor to be about 0.27 g/mi. One 

reason for this difference in particulate emission factors 

is, as already mentioned, that the previous study assumed 

a NOx standard of 1.0 g/mi for LOOVs (and its equivalent 

for LOOTS) while this study has assumed a 1.5 C?/rni NOx 

standard for LOOVs and 2.3 g/mi NOx for LOOTs. The 

remainder of the difference (approximately 10 percent) is 

due to small differences in overall diesel sales 

projections and total light-duty VMT in 1995. It should 

be noted that. the previous study projected nearly twice 

the level of LOOV penetration as this study (20 percent 

versus 11. 5 percent), but only 60 percent of the LOOT 

penetration (20 oercent versus the current 33.9 -percent). 

Thus, the net effect of t~e two differences is very small. 
2-24 

1995· urban emissions to be 79,000-97,000 metric tons per vear 

(uncontrolled) and 28,200-34,600 metric tons per year 

(controlled, 0.25 g/BHP-hr standard in 1986). [121 These 1980 

estimates are closer to those in Table 2-10 than the orev iou s 

light-duty diesel estimates. ~or best estimate sal~s, the 

current relaxed-scenario estimate is about_ equal to the lower 

limit of the previous uncontrolled scenario estimate and is 

only about 20 percent le~s than the upper limit of the pr~vious 

uncontrolled scenario estimate. The current base-scenario 

estimate is only about 5-20 percent higher than the orevious 

controlled scenario estimate. The results for the worst case 

sales' scenar.ios are similar.* 

The information presented above is summarized in Table 

2-12 (best estimate sales) and Table 2-13 (worst case sales). 

The mid-points of the emission ranqes contained in the previou~ 

studies are shown in Table 2-12 (and the upper 1 imi ts shown 

inTable 2-13), because the mid-points represented what was then 

EPA's best estimate of diesel penetration and the upper limits 

represented what was then EPA' s worst case estimate of diesel 

penetration. 

Both tables are oraanized in a hierarchical fashion, with 

those scenarios yielding the highest urban emission estimates 

located near the top and those yielding the lowest estimates 

near the bottom. Also shown (in parentheses) are the degrees 

of emission reduction from the oriainal uncontrolled emission 

estimate compared to that provided by the orig in al controlled 

emission estimate • 

. • ·- · ~s -ca.n. b,e .seen from Table .. 2."".12, the .base .. scenario orovides 

'about· -f:;e·-·saine control .as - that"- estimatea:::·,'fo·r -essentia-lly ~-the· 

same controls 3-4 years ago. On the other hand, while 

emissions under the rel axed scenar·io are 60 percent greater 

than those under the base scenario, the relaxed scenario st i 11 

orovides 74 percent of the original reduction projected for the 

trap-based particulate standards. 

* The difference between the current relaxed-scenario 

estimate and the previous uncontrolled estimate is 

primarily due to: 1) the current analysis oresumes a 

decrease in engine-out HOOE emissions from 0. 70 g/BHP-hr 

to 0.60 g/BHP-hr in 1988, and 2) vehicular emissions in 

the current study are projected to decrease with future 

increases in HDDV fuel economy. 'T'he difference between 

the current base-scenario estimate and the previous 

controlled estimate is due to the more detailed fuel 

economy and fuel consumption estimates that are used in 

this study. 
2-25 

Table 2-12 

Comparison of Current Urban Emission Estimates 

to Those of ·Previous Studies - Best Estimate Sales 

Scenario 

Original 1979-80 

Analyses (Uncontrolled) 

Relaxed Scenario 

Intermediate Control Scenario* 

9ase Scenario (HDD 

Control Only) 

Base Scenario 

Original 1979-80 

Analyses (Controlled) 

* ~el axed scenario 

HDDVs. 

.. ·--;·. 

........... -·· ~ 

:..·..:: .. ·:.,;, 

Total 1995 

Urban Emissions 

(metric tons oer vear) 

239,000 

114,000 

92,000 

78,000 

71,000 

71,000 

for LDDVs and LDD'l' s, 

-~···· -~ .. 

. '• ,. ·~ ... 

Reduction from Original 

Uncontrolled Emission 

Estimate Relative to ~hat Provided By Original 

Controlled Estimate 

74% 

88% 

96% 

100% 

100% (base) 

0.4 g/BHP-hr standard for 

,. ···- .. 
2-26 

Table 2-13 

Comparison of Current Urban Emission Estimates 

to T~ose of Previous Studi~s - Worst-Case Sales 

Scenario 

Orioinal 1979-80 

~~alyses (Uncontrolled) 

Relaxed Scenario 

Intermediate Control Scenario* 

9ase Scenario (HDD 

Control Only) 

9ase Scenario 

Original 1979-80 

Analyses (Controlled) 

Total 1995 

Urban Emissions 

(metric tons per year) 

2 87, 090 __ 

l!i2,000 

137,000 

120,000 

106,000 

85,000 

Reduction from Origi~al 

Uncontrolled Emission 

Estimate.Relative to 

That Provided By Orioinal 

Controlled Esti~ate 

62% 

74% 

83% 

90% 

100% (base) 

* .~e t.a.xe,d_ .. sE,e n~ r .i o for LDDVs __ . SiOd_. ___ Lq~n,~-~~' .. Q .• 4 g /2f:1P-h_r ._ .. s ta nda r.d .. _ f o.r 

..,_·HDD\.r.s-.-""·.c· ,_ .·'· -···J-- -- -·-.··-· ··-~·-· · ····- · -·- --··- · · - · · . . · - .---· ···-:-- ·;:··.,·;;·;.::·. 
2-27 

Two alternate scenarios are also shown in Table 2-12. 0ne 

is the base scenario with further controls placed only on HDDVs 

(i.e., relaxed scenario for LODV and LDDTs). 't'his scenario 

still provides nearly the same control (only 4 percent less) 

t~an that originallv orojected for the base-scenario 

standards. The other is labelled "Intermediate Control 

Scenario," and consists of the relaxed scenario for LDDVs and 

LDOTs and an· intermeciiate 0.40 a/BHP-hr standard for HDDVs. 

(Intermediate standards were not considered between t!ie 

relaxed- and base-scenario standards for LDDVs and LDDTs 

because the difference between the two sets of standards is 

already very small.) This scenario provides 88 percent of the 

reduction originally projected for the trap-based standards. 

Thus, based on the information contained in Table 2-12, it is 

possible to obtain most, if not all, of the control originally 

?rejected with standards less stringent than the trap-based 0.2 

g/mi, 0.26 a/mi and 0.25 g/BHP-hr tor LDDVs, LDDTs and HDDVs, 

respectively.* 

As can be seen from Tahle 2-13 (worst case diesel sales), 

the order of the various scenarios does not change 

sianificantly. f1owever, none of the current control scenarios 

provides as great a reduction in emissions ~rom the original 

controlled scenario for worst case sales when com~ared to those 

which occur for the best case sales (Table 2-12) • The base 

scenario onlv crevices R9 percent of the oricinally projected 

control and the relaxed scenario provides only 61 percent of 

that control. The two alternate scenarios fall in between. 

This dif:erence from the results of ~able 2-12 is due primarily 

to the increased severity of the worst case diesel penetrations 

of this study as compared to those of the previous studies. 

:. :.'t . . l:. ~.:.~~~ •. 

* It should· he rememhered that the oresent analysis assumes 

~Ox standards of l.5 and 2.3 g/mi for LDDVs and LDDTs, 

respectivelv. The effect o~ 1.0 and 1.2 g/~i NOx standard 

for LDDVs and LDDTs, respectively, which were assumed in 

~revious analysis, is addressed in Chapter 10. 

. ., '' .. ·~~ .:·· .:,' 
. -- - ~ -- r; •I - '' 

2-28 

References 

1. · "Characterization of 

In-Use Diesel Vehi~les," Gibbs, 

801372, October 1980. 

Particulate Emissions from ~., et al., SAE. Paper No. 

2. "A Study of· Exhaust Emissions from Twentv High ~ileage Oldsmobile Die~el ~a~~erigei t~~~," U.S~ EP~, OANi, OMS, 

ECTD, TEB, March lq8o. 

'3. "Reoulatory Analysis of the Light-Duty - - ··Particulate-· Regulations - ·far 1982 · and ·Later· Model 

Lioht-Duty Diesel Vehicles," U.S. EPA, OANR, OMS, ECTD, 

February 1980. 

Diesel 

· Year 

SDSB, 

4. Letter ano SupJ?lement from C. L. r,ray, TJ.S. "'.:PA, 

ECTD, to T. Young, Engine Manufacturers' Association, July 19, 

1983. 

5. "Trap-Oxidizer Feasibility Study," U.S. ".:PA, OANR, 

OMS, ECTD, SDSB, March 1982. 

6. (Internal ~emo from T. Darlinoton to P. Lorang. T~is reference to be constructed at later date.) 

7. "Compilation of Air Pollutant Emission Factors: ~ighway Mobile Sources," U.S. 

SPA-460/3-81-005, March 1981. 

EPA, OANR, OMS, ECTD, TEB, 

8. "T~e Imoact of Lioht-Dutv Diesel ?articulate 

: : .. -: :':.s.{a·n·d-a::id·s: ~.dn·'~th-e· "'~te~v.e-1 -o-C:'.:G>.fEfse~l- '."p:en·e'.f.f a:t.io 6': .. in· ... t!ie~ .,L igh:t •.Du t:V. __ -:-_ 

~lehicle a:1d Lioht-outy Tr.uck Markets," ·jack ·raucett. Associates' ... _ 

for U.S. EPA, EPA Contract No. 68-01-6375, January 17, 1983. 

9. "U.S. Lona Term Revi_ew," Data Resources, T nc., 

Summer 1982. 

10. "The Highway Fuel Consumption Model:" Eiqhth 

Quarterly Report: Enerov and Environmental Analysis, Inc., 

for U.S. DOE, DOE Contract No. OE-AC01-79PE-70032, July 1982 • 

. 11. U.S. Federal Highway Administra~ion data as 

contained in "M>IMA Motor Vehicle Facts and Fioures '82," ~otor 

Vehicle Manufacturers Association of the U.S., Inc., Public 

Affairs Division, 1982. 

12. "Draft Reaulatory .?l.nalysis 

Particulate Regulatio.ns," U.S. F:PA, OANR, 

December 1980. 

Heavy-Duty 

OMS, ECTD, 

Diesel 

SDSB, 
CHAPTER 3 

AIR QUALITY I~PACT AND POPULATION EXPOSURE 

I. Introduction 

In an at temot to olace the impact of the urban emission 

estimates of the. previ;us chapter. in a better perspective for 

assessing both health and welfare impacts, this chapter 

estimates the air quality impact of and population exposure to 

diesel particulate. emissions in 1995 under the va.rious diesel 

sales and control scenarios outlined in Chapter 1. This is 

accomplished in four sections. 

The first section outlines and uses a methodology for 

deriving nationwide averaqe diesel particulate emission factors 

for 'urban areas in 1995~ 'l'hese scenario-specific nationwide 

average diesel particulate emission factors become the primary 

input to the following three sections. 

The second section of this chaoter uses atmosoheric lead 

monitorina data as a. surroaate to e"stimate atmosoheric levels 

of diesel particulate in .1995 under the vario~s scenarios. 

This analysis will provide estimates of ambient diesel 

particulate concentrations at one or two particular monitor 

locations in a large number of U.S. cities, with basic input to 

the model consisting of national fleet-wide averages. These 

1995 particulate concentrations are then compared both to each 

other and to 1980 levels. 

The third section is concerned with a similar analysis of 

four types of localized areas which are particularly sensitive 

to motor vehicle emissions. These microscale areas include 

urban expressways, street canyons and enclosed spaces such as 

parking garages and roadway tunnels.- - . •#. • .. ......... ~·· .... ~ ·~ 

:-:> •. :: .:. Wh'i i'e'·i'·"' y i·e"l d i ng ., ,. ~., est i·ma•t e S"' · ' 0~0:f,:.~ . ·: .:J:te s e 1: .; : ·~ pa.r .. t icu late ::~'t"' ~'' :: 

concentrations in particular locations, neither t!:e urban nor 

localized air quality analyses address overall population 

exposure as oeo!)le move from location to location within an 

urban area. ~his is done in the fourth section of this chapter 

bv estimating the actual exposure of individuals to these 

concentrations: these results can then be used to assess the 

cancer risk associated with diesel particulate. The exposure 

analysis uses a CO exposure model which was developed by EPA's 

Off ice of Air Quality Planning and Standards (OAQPS) for use in 

evaluating alternative CO National Ambient. Air Quality 

S tan d a rd s ( ~AA Q S ) . S i n c e s tu d i es show th a t the g r ea t ma j o r i t y 

of CO concentrations in the atmosphere are mobile source 

related, it is felt that CO is reasonably representative of 
3-2 

vehicle pollutant trends and, therefore, can serve as an 

acceptable su r roqa te for d iese 1 oar t icu late matter in exposure 

model i ncr. It sh-ou ld be noted that those sources of CO which 

are not motor vehicle related, such as indoor sources, are 

removed from the moQel for this analvsis. 

A final section is included in support of the theories 

behind the air aualitv analysis to be cerformed in this 

chapter. By examininq trends in historical emissions versus 

a~bient concentrat·ions ov~r a period of time, a direct 

correlation is demonstrated for both lead and CO; this supports 

the rollback theorv that emissions can be used to oredict 

ambient concentrations. Also included in the fin al sect ion is 

a comparison of this chapter's air quality projections to those 

contained in a recent SPA study. Ambient diesel particulate 

concentrations for 1980 are calculated using the models 

contained in both reoorts; U?On comparison of results, their 

similarity demonstrates support for the lead surroaate model 

used here. 

! t should be remembered that the methodoloq ies described 

in Section II through IV utilize the ambient measurement of 

other pollutants (lead 3nd CO) to esti~ate the future year 

(1995) concentrations of diesel particulate. None of the 

models are based on actual measurements of urban levels of 

diesel particulate. As with any indirect analysis method, the 

absolute accuracy of this met~odology is not well known because 

direct measurements of the pollutant of interest in urban areas 

cannot he made. (It is difficult to distincruish diesel 

oarticulate from ot~er airborne carbonaceous oartic'Jlate.) For 

this verv reason, these surrocrate techniaues are orobablv the 

:nost sui"table aporoaches currently available for proje-ctinq . -- diifs:e1' o·ar.ttcula"te· conc'e'nfrations "Tn·"" num·et"6i..!s ate"'as···aro"ur.d the"".:" -~· -~~":!"~t~ . - "'.:.~,. ~ _. .... ! "': - ... ~· .. ~- •.. ~ • ...... 

r_r • S • 

It is also imoortant to point out that national-average 

inout data are used throuahout this analysis. Such oarameters 

a s · the le ad con ten t o f g a so 1 in e , v eh i c 1 e ~ ix , d i es· e 1 ma r k e t 

penetration, VMT growth, pollutant dispersion characteristics., 

temperature variations, etc., can vary both reqionally and 

locally; changes in these parameters would, in turn, have an 

effect on the projected diesel particulate concentrations. 

Therefore, care should be taken not to overemphasize the 

indivi<lual diesel particulate concentrations projected for 

specific cities (listed later in the chapter). More accurate 

estimates for particular cities could be made if the specific 

traffic characteristics for that city were used; however, an 

indivic1ual city-by-city analysis was beyond the sccpe of this 

reoort. Instead, the primary purpose of t~e model-lng efforts 

in this chaoter is to estimate the effect various levels of 

emission control will have on future urban concentrations of 

diesel particulate across the nation as a whole. 
3- '3 

II. Nationwide Diesel Particulate Emission Factors 

The first step in estimating either annual average ambient 

particulate levels in U.S. cities or the nationwide averaae 

urban population exposures is to derive fleet-wide urban diesel 

oarticulate emission factors for urban areas for each of the 

four scenarios. To do this, the orocedures outlined in Chapter 

2 are reoeated to netermine the average diesel oarticulate 

emission factor for each vehicle class and scenario ~s shown in 

Tahle 3-1. (reproduced from 'rable 2-8. of Chapter 2). The 

emission factors for each vehicle cateaory in a oarticular 

scenario are then combined according to the weighting of their 

lq95 urban VM'r, which can be derived from the projected VMT 

data in Table 3-1. 

~able 3-t aqairi s~ows the particulate emission factors for 

each vehicle category/scenario, the derived urban VMT breakdown 

for 1980 and 1995, and the fleet-wide, urban oarticulate 

emission factors for each scenario. Also shown is a breakdown 

of each vehicle class' contribution to urban emissions under 

each scenario. 

III. Urban Air Oualitv Analvsis 

Since diesel ?articulate is not e3sily distincuishahle 

from other carbonaceous particulate, air quality monitoring 

data are not presently available for diesel particulate, 

especially under the conditions expected to exist in 1995. 

1'hus, anv :nethod for estimatinc diesel oarticulate air qualitv 

impacts must use some measurable surrogate in the ambie.nt air 

that is directlv relatable to automobile emissions. Various 

studies in the ?ast have used such substances as lead or CO to 

provide a link between vehicle emissions and air cuality. Once 

thi.s lin~. is established,. th.en ·,;ehicle e:nissions of the·· 

surrooata substance are ·related to diesel oarticul~~~=D~~~~ 

emissions, resulting in an estimate of diesel particulate air 

auality i:noacts. 

The fairly strong correlation between ambient 

cor.centrations of lead and carbon ~onoxide documented in 

various oublished reports [1-41 supports the theorv that both 

are representative of mobile source contributions to air 

aualitv. 0bserved concentrations of Pb and CO in Los Anoeles 

in 19 a· O [ 21 show the two po 11 u tan ts to ex h i b i t very s i mil a r 

monthlv and seasonal variations: a linear reoression of matched 

co'ncentration pairs of the two pollutants yields an r2 value 

of 0. 7980. .A.lthouah the actual ratio of CO/Pb varies from 

study to study because of yearly chances in gasoline lead 

contents, the coefficient of variation from the mean ratio is 

fairly consistent, ranaing from 20 to 26 oercent [1,2,41. It 
3-4 

Table 3-1 

·weiahted Emission Factors and Pro1ected VM'T' 

Weighte~ Emission Factor 

(a/rni) 

Calendar Year 19Rn: 

All Scenarios 

\.alendar vear 1995: 

Best Fstimate Diesel 

Sales 

Relaxed Scenario 

Base Scenario 

LDV 

n.ooc;q n.nl174 

n.n272 0.0760 

0.0205 0.0711 

Worst-Case Diesel Sales 

Relaxed Scenario 

Rase Scenario 

?rejected Nationwide 

~,M,,.. (1 n Cl mi 1 es) : ( 1 R l 

·~ - .... : ... ~ ... 

--1ae-n-- . · '19 BIS . 

.1qa5 

...... ~.~ ..... ---·· ~---- ~· ...... -

Urban Fraction of u!-1'T': 

( a 11 '' ~ a r s ) 

Prhan VMT (10 9 miles): 

1980 

1986 

iq9c; 

o. n11nEi n • l 1 7 0 

0.0460 0.1092 

. .. ----1 , 11· 8 .. ~ ._ - 2 (') 8 . q 

· · i·,-22'0 .. ~--· ·24:y·:·o 

1,517 32Q.c:. 

~64.l 

724.7 

913.n 

48.8 

l(') 1. 9 

117.6 

11'0.8 

~DV/LPDV 

n.nf176 1. 911 

0.4130 1. Ii 589 

0.2020 0.8499 

0.8088 1. 7f'l25 

(). 3864 n.8753 

~-38:. 8 · - · ...... ·7-1--.·R ·· 

· -·4·1. 2 ·s·c:;·/7 · · 

SS.2 117.Q 

48.8 

18.9 

20.l 

2Ei .. CI 

26.9 

l<L9 

23.l 

31. 7 
3-5 

Table 3-2 

Derivation of National Averaae 

Diesel Particulate Emission Factors (a/mi) 

LDV 

LDT 

MDV/LPDV 

H~nv 

Urhan VWT' 

Breakdown (%) 

icrno 1995 

82.5 80.6 

12.7 14.2 

2.3 2. 4 

2. 5 2.8 

Fleet-Average 

Urban-'TMT 

Weiohted 

Emission Factor 

<).0059 

o.n074 

().0676 

1. q 130 

0.0552 

~mission Factor (a/mil 

Best Estimate Worst Case 

Sales Sales 

Relaxed ~ase ?el axed Base 

n.0212 0.0205 Cl.Of'i06 n.24fin 

n.n7f'in n.n111 0.1170 0.1092 

0.4132 n.2022 0.8088 0.3Rli4 

l.658Q n.94qq 1. 70 2 5 n.~753 

0.0891 0.0554 0.1324 n.0863 

Vehicle I.lass Contribution to TJrban Emissions % : 

Lr'IV 8.8~ 24.6% 29.9% 36.9% 43.0~ 

LD,,. 1. 7% 12.1% lq.2~ 12.5% 18 .CH 

"1DV /LPDV 2.A% 11. 0% 8. 7"' 14.5~ 10.7~ 

Ul;f)V 8fi. 7, C:.2.3% 43.2~ 3f:.O~ 28.4, 
3-6 

should be noted that the L.A. study [2] showed a sliqhtly 

oreater correlation between elemental carbon (EC) and both Pb 

and CO: r2 values for EC/Pb and EC/CO were 0.8907 and 0.8881, 

respectively. The above correlations, along with the knowledge 

that approximately 90 percent of all fine elemental carbon 

(less than 10 um diameter) in the atmosohere is estimated to be 

due to mobile sou~ces [5], leads to the conclusion that 

elemental carbon could also possibly serve as a surrogate for 

diesel particulate in orojectinq future ambient air quality. 

To date, however, t!"ie most common! y used surrogates are lead 

and carbon monoxide. 

Qne methodology, which has been used in the past bv GM and 

EPA, uses· lead as a surrogate for diesel particulat·e. [6,7] 

This tvoe of analvsis uses historical data from urban sites in 

the n~~ional urb~n lead monitoring network as an index of 

mobile source pollutant levels. An estimate is made of the 

fleet's automotive lead emission factor which caused the 

observed ambient lead levels, and is compared to the expected 

cHesel particulate emission factor. Very generally speaking, 

if ~iesel particulate emissions in 1995 are expected to be 

twice automobile lead emissions in 1975, for examole, then 

ambient diesel particulate concentrations in· 1995 can be 

exoected to be twice the 1975 ambient lead concentrations. In 

this case, 1975 monitorinq data was chos<;!n over more recent 

data to avoid, for the most part, the errors associated with 

estimatino the leaded/unleaded vehicle mix. 

~he basic mathematical expression of this methodology is: 

C (D), 995 = ?rejected ambient concentration of diesel ?articulate 

(ug/m3'") 

:=.: (D) 1995 = Fleet-average diesel particulate emission 

in 1995 (g/mi) 

factor 

E(?b) 1975 = Fleet-averaqe emission factor for lead in 1975 

(a/mi) 

S(D) = Dispersion factor for diesel particulate e~issions 

S(Pb) = Dispersion factor for lead emissions 

VM~x = Total urban vehicle miles travelled in year x 

~(Pb)1975 = Urban ambient lead concentrations in 1975 (ug/m3) 
3-7 

A fleet-wide lead emission facto e foe 19 7 5 was ca lcu lated 

using formulas and tables developed in a recent EPA report. (8] 

Vehicles from 1956 to 1975 were considered, along with 

associated travel fractions and fuel economies. The 

calculations accounted for lead emissions from leaded, 

unleaded, and mis fueled vehicles: for 197 5, the national 

average lead contents for "leaded" and "unleaded" aasolines 

were 1.82 and 0.014 grams/gallon, respectively. Amount of 

consumed lead that is emitted ·with the exhaust was assumed to 

be 75 percent for leaded-fueled vehicles and 30 percent foe 

vehicles designed to use unleaded fuel. Separate emission 

factors were calculated for each of five vehicle classes (LOV, 

LDTl, LDT2, HDTl, and HDT2) , and then we re weighted according 

to their relative urban VMT's to arrive at a fleet-wide average 

lead emission factor foe 1975. 'T'he final calculated value was 

0.12n5 grams of elemental lead per vehicle mile travelled. 

Dis?ersion factors for diesel and lead particulate matter 

were determined throuah a 

literature. tt was qenerally 

·that diesel particles are 

compared to particulate 

gasoline. [8-11] 

review of available data and· 

concluded in all examined studies 

relatively small in diameter, 

matter produced from leaded 

'!'he majority of the diesel particles are found to fall 

within the "accumulation mode" (0.023 to l.O um) [10], with the 

median diameter between 0.10 and 0.25 um. (9,101 Due to its 

small size, diesel particulate disperses similar to a gas: 

therefore, S (D) equals 1.0. 

~rrivinq at· a lead dispersion factor for the model 

involved a review of findings from studies using various 

methods of analvsis. [1-5,12-17] One l'Tlethod of ~stimatinq lead 

: -a is t?~(s~Lo'n·:.:- i"s~·~-t;S'a·~ e~d .• : 'i;loql1-~ J~b,e,~,~ ·:'.pa r .. t.fc:l~. ~ :s.f z e~~·-.• d is tr i bu t~l:o.n's 'o~f: ~: c "•::·:; ·:.: ... 

i·ea·~ in both v.·ehic .. i"e .... e»<11a·us't'·a-nci., q.mbient air· -·samples~--. sefore 

comparing the two distributions, a "cut-off" diameter of one um 

was chosen: Cantwell, et. al., rl4] states that "particles of 

less . than one micron in diameter ••• (will) become airborne and 

remain suspended for a sianificant l~ngth of time." 

Huntzicker[41 estimates that approximately 25 percent of all 

exhausted lead particles are less than one ~icron in diameter, 

while about 64 percent of all airborne particles fall into this 

ranqe. a.ssuming that all particles with diameters less than 

one micron will become airborne, a lead dispersion factor of 

0.39 was calculated (0.25/0.154). Tn other ·,.rords, an estimated 

39 percent of all exhausted lead particles will become 

airborne, based on a particle size "cut-off" of one micron. 
3-8 

Another method of estimating S(Pb) in the model is to 

relate emission and ambient levels of lead and other 

vehicle-related pollutants, such as CO and ~C (elemental 

carbon). Based on calculated 1980 emission factors and ambient 

concentrations for Pb and CO, dispersion of lead is estimated 

at values between 33 and 44 percent.(1,41 Assuming EC 

disperses much like a oas, Cass' [51 ratios of EC/Pb for 

"highway s igna tur e" versus ambient conditions can be used to 

calculate a 57 percent lead dispersion factor. 

Other methods of estimating lead dispersion include soil 

analvses and actual measurements in enclosed areas. ward[l7l 

found that approximately 42 percent of exhausted lead remained 

airborne: he acco-unted for deposited lead in analyses of soil 

and vegetation within 250 m of a low-traffic state highway. 

Cantwell, et. al., [141 reports the results of a study where 

vehicles were driven back and forth inside a sealed tunnel: 

when exhaust emissions were compared to ambient concentrations 

inside the tunnel, it was found that 46 percent of the 

exhausted lead particles remained airborne. 

Averaging the results of these various studies, one finds 

that approximately 43 percent of all ex'.-:austed lead particles 

become airborne: therefore, a value of O. 4 3 is used for s (Pb) 

in the model eouation. 

It should be noted that only lead monitors in areas of no 

known large stationary sources of lead we re chosen for this 

analysis: the majority of the non-automotive sources of lead 

emissions resirle in a few identifiable areas which have been 

excluded f.rom this analysis. F'or these reasons, it can be 

assumed. that 100 percent of_ ambient _l~a9 .<::.a!1 b~ attrib.tJt~d to 

mo b,ile ·S 0 u r c es .. (.:i.n ·."the -con.t,e x t. -0 f -th i,5;-.-s-t-u.dv-)··,_:.·d e sp-i:te· ·-t-he- fact-·-<.'<::· 

that, ~ationwide, mobile sources only accou~t for ~oproximately 

88 percent of Bll lead emissions. [121 

The nationwide VMT and urban estimates presented in Table 

3-1 show :..Jrban VM'!' growth to be 40 oercent hetween 1980-95. 

Since the Energy and Environmental Analysis projections[l8] do 

not oo back to 1975, a second DOE-sponsored study was used to 

derive the urban VMT growth between 1975-81)~ T!'lis Oak Ridqe 

National Laboratory study estimated V~T growth to be 14 percent 

between 1975-80. (191 Combining these two figures yields an 

overall V~T growth between 1975-95 of 60 percent. 

The use of 

following oeneral 

monitored ambient 

diesel particulate 

the factors mentioned above results in the 

equation, which can be used to convert the 

lead concentrations into estimates of urban 

concentrations: 
or 

C_ (D)' 199 5 

E(D) 1995 l 0 

= 0.1265 orams lead X 0:43 X 1 • 60 X C(Pb)l97S 

mile 

C(D)1995 = 29.4 E(Dl1995 X C(Pb)1975 

Since each of the four scenarios in this analysis has a 

specific average diesel particulate emission factor (E(D)) 

associated with it, four discrete conversion factors are 

?reduced . relating. urban ambient concentrations of lead to 

diesel oarticulate levels. As an example, using the fleet-wide ur~an diesel particulate emission factor for best estimate 

sales and the relaxed scenario from Table 3-2 results in a 

factor of 2.62. T~is means that 1995 urban diesel particulate 

concentrations are projected to be 2.~2 times larger than 1975 

urban lead levels. 

'!'able 3-3 presents the lead-based estimates of diesel 

particulate concentrations for each scenario for 28 cities 

included in the National .~ir Surveillance Network (NASN} for 

lead in 1975. These monitor stations were selected from a 

larqer lead data hase as thev were known :o be in areas havina 

no large stationary sources of lead emissions, and to be above 

12 meters in height in order to best reoresent large scale 

average urban lead concentrations. Table 3-4 presents the 

range of concentrations of diesel particulate for each sce~ario 

as a function of city size. 

:or the best estimate sales and relaxed ?articulate 

standards scenario, the ambient air diesel oarticulate . _. ·:e:9·f'1ce'h.tr·a:t''i:oniL"r·a·ng~("'-from· ·,f .. Tow: .«'.:>"f ;r:i·'u·q;m3 ... fi:;>:r_ ... t.he·:. c~it.y . ._o'l ~,~'-:-,·~~ .. _ ~;» . . . -. " . i a ii' s a: s . c i t y , .. !<ans <is t 0 a - h i g h 0 f 7 • l u g Im 3 i n L 0 s . Ange 1 e s • 

~h~ other scenarios show similar ranees with the highest 

orojected concentration occurring in the worst case sales, 

relaxed standards scenario, as excected (10.5 ua/m3}. In 

comparing the best estimate sales ~cinarios it can hi seen that 

the base scenario will result in an estimated 38 percent 

reduction in the 1995 ambient diesel particulate concentrations 

comoared to the relaxed scenario. T~is could constitute as ;iiuc~ as a 2.i; uo/m3 reduction (Los Angeles) ·or as little as a 

0.5 ua/m3 reduction (Kansas Citv, ><ansas) in diesel 

?articuiate level5. - · 

':'his same methodology can also be aoolied to 1980 diesel ~artic:ilate emissions to show the change in estimated ambient 

diesel particulates bet·,,een 1980-95. r;sing the 1980 diesel 

?articulate emission factors from Table 3-2 and a VMT growth 
- ~ -i:.. -,, 

3-10 

Table 3-3 

Amhient biesel Particulate 

Concentrations Based on Lead Surroaate vonel (ua/m ~· 

Best Sst1mate Sales Worst ~ase Sales 

C"itv 1980 ?el axed Base Relaxed Rase 

Pooulation Greater Than i,oon,on.o 

Fouston 2 • c; 5.5 3.4 8.1 'i • 4 

Los Anm~les '3 • n 7.1 4. 4 ln.5 i; • 8 

"Jew York 1. 2 ?. • 8 l. 7 4 .1 2.7 

Philadelohia 1. 'i 3 • c; 2. 1 5.2 3. 4 

l.4 3. 2 2.0 4. 8 3.1 

Pooulation ~etween :;rrn,ooo and 1,000,000 

-qoston 1.1 2. 5 1. 5 3.6 2. 4 

Denver 1.1 2. s 1. 5 3.7 2. s 

Kansas Citv n.q 2.1 1. 3 3 .1 2.0 

"Jew Orleans l. 3 2.8 1. 7 4 • 2 2.7 

Phoenix 2. s 5. 5 3 . 4 8.1 5.4 

? it t!=;bUr<;Jh 0.9 2. 2 1. 4 3. 3 2.1 

San Dieao 1. 3 3.0 1. B d • 4 2.9 

St. Louis 1. 4 3. 1 i·a . , 4. 6 3.0 

-copulation Between 2 511, one and 500,000 

!':lanta :!. • 2 2. 8 1. 7 4 • l 2.7 

3ir:ninaham l. 4 3. 2 2.n 4. 7 3. l 

r.incinnati I'). 9 2. l 1. 3 3 . 2 2. 0 

Jersev <:i+:v 1. 2 2.7 1.7 4 . 1 2. 6 r:,~o~u;i:sV._il l.e~~ " -- .: -- i... 2 .. --_·_ -.... -,. '"') •:fi- ·~ -._~ . -·- 1.. f;, ..... : - ::- ' - 3 ··- 7 ,., -.... : ..:.: i ~ 1;·.·_ :-_-_~-. 

Oklahoma <:itv 1. 9 4.4 2 . .7 6.4 4. 2 

1. 2 2.7 1. 7 d • () 1 • i; 

Portland n . 9 . 2. 1 1. 3 1 • 2 ?. • 0 

~'JCSOn n. 8 1. 9 1. 2 2.9 1. 9 

Yonkers 1. 4 3.0 1. 9 4. 5 3.0 

Pooulation Between l no, 0011 and 2511,000 

i(ansas City, KA 0.7 1. fi 1. 0 2. 4 1. 'i 

0 • c; 1. 2 0.8 1. 7 1.1 ~ohile 1. 2 2. 6 1. i:; 3.7 2 • c; 

'lew Haven 1. 3 3. 0 1. 9 4 . 5 2.q 

Salt Lake <:ity 1. 2 2 • fi 1. 6 3. 9 2 • 'i 

Sookane !l • 7 l. 5 1. 0 2. 2 1. 5 

Trenton 1.1 2. 4 1. 4 3 • 4 2. 2 

r.J a t e r bu r v 2.2 4. 9 3 . 1 7.3 ·4. 8 
3-11 

Table 3-4 

Averaqe Ambient Diesel Particulate 

Concentrations by ritv Pooulation (~q/m ~ 

1995 

Citv Size Grouping Fest Fst1mate Sales Worst 

("Dooulation) 1<:180 Pelaxe(l Rase ?elaxeil 

Greater than·· 1.2-2.7- 2.6-6.2 l.fi-3.9 3.9-9.2 

l,ooo,oon 

soo,oon-1,onn,noo 0.8-1.8 1.8-4.l 1.2-2.5 2.8-6.0 

2so,ooo-son,ooo 0.9-1.5 2.0-3.4 1.3-2.l 3.1-5.l 

ino,oon-2c;o,ooo 0.6-1." l.3-3.6 0.7-2.2 l.A-5.4 

Case Sales 

Base 

2~6-fi.n 

1.8-3.9 

2.0-3.3 

1.2-3.5 

* Rances are averaqe values clus and minus one standard deviation. 
3-12 

rate of 14 percent (as indicated previously for 1975-80), a 

conversion factor o.f 1.16 is calculated; this factor, 

multiplied by the indivioual ambient lead concentrations, 

yields the 1980 estimates of urban diesel particulate 

concentrations found in Tables 3 and 4. As can be seen, 

ambient diesel part icu late levels in 19 9 5 will increase over 

1980 levels under all scenarios. For examole, between 1980-95, 

diesel oarticulate concentrations in Los Angeles would increase 

by 4 .1· · ug/m3 under !)est estimate sales· and the· relaxed 

scenario, •1ersus 1.4 uq/m3 under best estimate sales and the 

base scenario. 

Another characteristic difference between the present ··::i:ir 

(1980) urban ambient diesel particulate projection and the :;95 

projections are that the proportion of LDDs versus :!DDs and 

hence their impact on air quality are substantially different. 

LDDs produce only 12 percent of total diesel ?articulate 

emissions in 1980, but between 3n and ~l percent in 1995, 

depending on which scenario is chosen. ~or a city such as Los 

Anaeles, this translates to an increase in urban ambient LDD 

?articulate concentrations of 2.1 ug/m3 and 2.2 ug/m3 for 

base and relaxed standards with best estimate sales, 

respectively. Of course, by analogy the i~oact of heavy diesel 

vehicle cateaories (MDV/LHDV and ~HOV) ~n urban air quality 

( 19 9 5 v er s us 19 8 O ) is pro po r t ion ate l y less than the over a 11 

fleet, though in absolute terms still increasing. 

Prior analyses have been performed by ~PA on the impact of 

diesel oarticulate on urban air quality. '!'he fTlost pertinent studies· are those done for the reoulatory analyses for the 

light-duty diesel particulate standards and the ~DD particulate 

standards. [20,211 In both of these regulatory analyses an 

identical lead-based air quality orojection was made for diesel 

oar'.t_iC:U la 'te ..... ~-The .. oQrY ~-a ff.feience s.: Seb~.ee'n.·~· .t.h e se ~ ?r.~)je:.C t iqn~. 

and t~e 9resent study would be the diesel particulate and lead 

emission factors, lead dispersion factor, and the year for . ..,.hich the projections 'Here made. 1'he :nore recent '!eavy-duty 

analysis will be used as the primary comparison to the present 

study. 

The analysis of the urban air quality i:npact resulting 

from diesel particulates, as calculated in this report, is 

aoproximately 45 oercent lower than the previo~s analysis based 

on a comparison between the midpoint of t!ie previous range of 

ar.ibient concentrations and the best esti:nate relaxed scenario 

in this analysis. For example, the urban ambient level of 

diesel particulate in this studv was esti:nated to be 7.1 

ug/:n 3 in Los An9eles under the best estimate relaxed scenario 

while the corresoondina value in the orevious analvsis for t'.1e 

uncontrolled fleet was- ap?roxi:nately ·12.9 ug/m3. -The primary 
3-13 

reason for this difference is the fact that non-trac emission 

levels fo.r LDDs are well below those projected three yea.rs ago 

and that the relaxed-scenario standard for qoos includes a 

slight degree (15 percent) of control. 

IV. ~icroscale Air Oualitv Analvsis 

Certain very soecific localized areas are known to be 

affected by motor vehicle emissions to a greater extent than 

ur~an areas as a whole rand the locations of · the lead 

monitors). Among these localized areas (hereafter called 

microscale areas) are urban expressways, street canyons, 

roadway tunnels, par~ing garages and ~esidential oarages. In a 

previous· effort by ;PA designed to _evaluate potential hazards 

due to unregulated pollutants emitted from motor vehicles, a 

set of ambient air dispersion models and model parameters were 

developed and validate~. (22] 

These models, ~hile mathematical in nature, were validated 

based on known concentrations of CO in these microscale areas. 

As such, these models can be considered reasonably accurate for 

the specific geoq r a ph ical and meteorological situations being 

examined. qowever, as the relationship between diesel 

particulate and CO emission factors may -:iffer under specific 

conditions, these models can only be considered to be oood 

estimates when applied to diesel ?articulate modeling. 

However, this approach is perhaps the best assessment available 

for localized estimates of diesel particulate concentrations. 

··'!'he aforementioned work identified a set of typical and 

severe sit'Jations for each of the microscale areas, differinq 

by •Jehicle traffic volume, •o1indspeed, ~nd other factors 

... -.-. :.;Jn.f Lu-enci:;ig, .amb.Je-n.t--conGen.tr.at,i ens ....... ':'he .r.e.su l t.s . of .... the .. e ar..ti-e r. -' ... ,., -=-~-,.-,, 

.. ·'· .. wo.r.k ... 'a 1 low-" cal cu l:a·t0i·on" of.> the···a:mb i:e-n t· .. ·a~i,r»-:".-:o~nc;en:t r-a·t·ion for· ·any: . .-:. ::.:· ·. -' ·""''• 

of. these microscale areas (in either the typical or severe 

situations) based only on the pollutant emission factor. If a 

pollutant is assumed to be evenly distributed within the 

microscale and is of low short~term reactivitv, then the 

pollutant emission factor is multiplied by the conversion 

factor (one for each microscale area situation) to obtain an 

estimate of the ambient concentration at the specific 

microscale location. 

Tab le 3-5 presents the various selected m ic rosca le a re as 

and their corres~onding conversion factors. These factors 

re ore sent the ambient concentrations of any applicable 

!)oilutant (based on above criteria) estimated to occur in each 

of these microscale areas for a vehicle emission factor of 1 

g/mi. These conversion factors can not be directly applied to 

lead emissions due to uneven distribution of lead throuohout 

the microscale (deposition/dispersion charateristics). 

However, CO, which is 100 percent dispersed, ·would be an 

applicable pollutant in this case. 
3-14 

't'ahle 3-5 

Summary of ~icroscale Situation Concentrations 

Situation 

l. Roadway Tunnel 

Tvoical - Lowry Fill, Minnesota 

Severe - Baltimore Farbor Tunnel 

2. Street r.anvon (sidewal~ receotor) 

Tvoical - 4 lane canvon, 800 vehicles/hr., 

8 m~h windspeed 

Severe - 6 lane canyon, ?400 vehicles/~r., 

2 mph windspeed 

3. On Pxoresswav (Wind: 315 dea. relative, 

2.2 mph) 

Tvoical - San Antonio I-410, 

Severe - Los Anqeles I-10, 

4. Beside ~xoresswav 

100 meters awav-downwind 

~icroscale· 

~onversion Factor 

( u a /m 3 oe r a /m i ) 

1,123. 

2,851i 

42 

282 

124 

50 ~ 
3-15 

The particular values listed in Table 3-5 for the tvoical 

situations were selected to be reasonably representative of the 

desired types of areas. The concentrations represented by the 

severe situation for each scenario would be expected to occur 

only a small percentage (1 percent) of ·the time on a nationwide 

basis. ~owever, in a given specific area, the severe case 

could occur much more frequentlv. For example,· the severe 

expressway situation used a segment of the Santa Monica freeway 

in Los Angeles, which is a 10-lane freeway with a 200,000 

vehicle/day traffic count. The windspeed and direction were 

typical of this location. While this kind of traffic flow is 

severe for most urban expressways in the nation (impossible for 

most), it is a r1efinite reqular occurrence for this expressway 

and other busy large expressways in large metropolitan areas.-

Thus, while the severe situation would not be expected to occur 

frequently on urban expressways in general, there is a real 

possibility of frequent occurrence in the few very busy freeway 

segments in large cities. 

Table 3-6 presents the results of the microscale area 

ca lcu lat ions for the four scenarios. The r anqe of lo ca 1 i zed 

diesel -particulate concentrations in Table 3-6 constitute an 

estimate of the levels which might be expected in these areas 

in 1980 and 1995. These levels are not to be construed as 

any th in g 1 i k e aver a a e u r ban 1 eve 1 s ~ r average per son a 1 

exoosures. In fact, the overall ~ooulation exposure 

contributed by these very high, short-term levels is probably 

relatively small. f.lowever, to the extent that the population 

is exposed as they pass through these microscale areas in their 

day to day activities, these localized area diesel 9articulate 

concentrations could constitute an i:npact on their health or 

welfare. 

-· .... . . Fo.r .. :exarriple.,.,·,~··h.i-.gh, ·loca1"-i"zed· :.;;·co·ncentrat·ions··· ·of· ·di·esel· · ~ -.... .. ..:.\.::· "pa"r-:E fc:~~-a t'·e 7":"·'6-n·~ '.an·:-- .:exp res s·.JiaY- ·· oo-i"ti.,;;.""·'\'.lg ;mJ Tti .:." 19"9 s·) ~_.. ·mav ·~o"e:; -!" -;:-.,,,., .•• : .... , .. ,l.' 

reflected in reduced short-term visi~ilitv or increased 

short-term odor which may impact on the health and welfare of 

the commuting public. qowever, current levels of diesel 

particulate in an identical situation could already be 

a~proximately 25 ug/m3. 

An examination of Table 3-6 shows the wide variety in 

potential localized area concentrations of diesel particulate. 

These projected levels range from as low as 2 ug/m3 for a 

typical street canyon under the best estimate sales and base 

standards scenario to as high as 378 ug/m3 for a severe 

roadway tunnel under the worst case sales and relaxed standards 

scenario. The lowest levels of this range roughly correspond 

to the overall urban area concentrations ?resented in ~able 

3-3. This finding is consistent with the fact that some of the 
3-16 

'T'able 3-6 

Microscale Diesel Particulate Concentrations (uq/m" 

1995 

Best Estimate Sales Worst Case Sales 

1980 Relaxed Base Relaxed Rase 

"( . Roadway 

Tunnel 

Tvpical 57 inn 62 l4q 97 

Severe 145 254 158 378 246 

I I. Street 

Canyon 

""Y?ical 2 4 2 Ii 4 

Severe 14 25 16 37 24 

TT T. 0n ~xoresswav 

'l'vpical Ii 11 7 16 11 

Severe 2fi 45 28 F, 7 44 

IV. BesicP. 

t:".xpresswav 5 ;. 14 9 
3-17 

fixed site monitors used ·in the lead ambient monitor netw.orl< 

are sited. in locations such as street canyons (on top of tall 

buildings) or near expressways and concentrations in these 

localized areas, under. typical conditions, may approach the 

overall urban area averaqes. 

~n analysis of the overall ~ifferences between the relaxed 

and base scenarios yields the same percentage differences as 

those found for urban emissions in general in Chapter 2. · These 

differences can be translated to an increase in · localized 

diesel particulate concentrations of from as low as 2 ug/m3 

for a typical street canyon situation to as high as 96 ug/m3 

for a severe roadway tunnel situation. Comparing the increases 

in ~hese projected 1995 localized diesel particulate 

concentrations to the concentrations which may be occurrinq now 

(1980) results in the observation that, for the severe roadway 

tunne 1 situation, oresent levels of diesel particulate may be 

expected to be on the order of 145 ug/m3, which can be 

comoared to the projection for the best estimate sales relaxed 

control scenario in 1995 of 254 ug/m3, or the projection for 

the best estimate sales base control scenario of 158 ug/m3. 

V. oooulation Exoosure Analvsis 

A. Tntroduction 

The population exposure estimates used in this report are 

based on a general air pollutant exposure model, called the ~lA;0s Exposure Model (\JEM) , develooed by OAOPS for the 

evaluation of relative population exposures under alternative ~AAOS [231. The NEM is an activity ~attern model that 

simulates a set of population groups called cohorts as they go 

''.: ·;::··~.b.P~:~'· ·.:~.he i.;;, .... q .. ~.Y:::.~!':-da Y .. ?Ct.iv it ~e ~ ! -,., ~ac.h .... oJ.-. .J:h.e .. se,, ,,coho,r-ts -.a·r·e . , _ ·. . ..... ,._r" .a.s.s-igned·. te" a .. ,. specifi,c::,rlo.ca . .t-io·n-~.t-y.pe .-a:ur·ir.g :e·ach ..... .hou'.t o·f, t"h'e:····\<• .. ';11.:~~- ~· 

dav. ~ach of several specific location types in the urban atea ar~ assigned a particular air quality value based on fixed site 

monitor ~ata. ~he model computes the hourly ~X?Osures for each 

cohort and then sums these values. over the desired averaging 

time to arrive at average population exposures and exposure 

distributions. Thus, the model simulates pollutant 

concentrations in urban areas by relating these concentrations 

to fixed-site monitor levels: in turn, the model simulates the 

activities of peoole bv relating the pooulation to a fixed set 

of cohorts with defined activity patterns. 

For example, ~ certain fraction of the total urban 

oopulation might ~e assignea to an off ice worker cohort with a 

~ome-work-home activity oattern. This cohort would experience 

a consistent set of microenvironments, such as home, 

t r ans po r ta t ion , and o f f ice , in a norm a l a a y ' s act iv i t y • ~a ch 
3-18 

of these microenvironments· would have an associated pollutant 

concentrat,ion related to the fixed-site monitor level for the 

specific time of dav and date. The fixed-site monitor levels 

are adjusted to correct for the differences that typically 

exist be tween the monitored locations and the m ic roenv i ronmen t 

location. These adjustments are general enough to .account for 

multiolicative and additive types of correlations between the 

monitors and locations. 

A unique feature of the model is that it ·separates 

concentrations, people, places, and time (all of the important 

inqredients of exoosure) into discrete elements. The 

concentrations are broken up into values determined bv the 

precision of the fixed site monitors (e.g., for co into ·whole 

integers of ppm). The people or urban population of an area 

are separ~ted into cohorts that are assumed to have soecific 

activity patterns and related exposures. The places are 

seoarated into a discrete number of areas which are assumed to 

have identical pollutant concentrations over a given period of 

time. Thus, the <iefinition of olaces may be influenced by the 

type of pollutant studied and its emission sources. Time is 

separated into the smallest unit of measure which is desired. 

Since this methodolooy was designed to be used with the NAAQS, 

which are based, at a minimum, on a 1-'.-.our time period, one 

hour is the shortest time period considered by the general 

model. tonger averagina times, such as 24 hours or a vear, can 

be obtained by calculating the appropriate averages from the 

1-hour exposures. 

The ceneral ~EM approach has been used by OAOPS to develop 

so e c i f i c mo a e 1 s f o r a numb e r o f c r i t e r i a po 11 u t an ts , such a s 

CO, c;o2 , N0 2 and particulate. [24] These oollutants have 

~ been s.tud_i,~d 0..Y aoolyi!}9 .. the specific ool_lutant data base _from ... , .... ·.-t·h-e · appropr.iate· EP·A monitoring· ~nogram and by -designing·'-ehe -~:::-· 

place desi9nations to those most a!'propriate to t'.:e oollutant • 

. ?lace or location designations .in the NEM are determined as 

exposure districts or ex?osure neighborhoods, depending on 

whether the pollutant of interest is a point or dispersed 

source of emissions, resoectively. The exposure district 

approach is more geographical in nature and relies on the fact 

that pollutants which are primarily emitted by large ~oint 

sources can be adequately characterized by exposure districts 

of fairly large areas. In contrast, !.'Ollutants with emission 

sources which are dispersed throughout an urban area (including 

mobile. sources) are best characterized by considering exposure 

neighborhoods with common exposure patterns. These 

neighborhoods may be spread out in a random fashion throughout 

the urban area. 
~he oeneral NEM ~odelino aooroach usino monitorina rlata in 

four cities (Chicago, Los Anoeles, Philadelohia, and st. r.ouisl 

was applied to the cd teria pollutants· mentioned ahov.o 

resultinq in four averaae exoosures and exposure 

distrihutions. a. limited set of 24 total monitors in four 

cities was used hec?Llse ~f the extensive comouter time reauirPrl 

to run the t..T'C'\4. A rouah nationwide exposure extraoolation has 

'-'een rlevelooed hv liAliP~, which involves relatino each of the 

larce urhan areas in tr.e countrv to the most similar of the 

four moneled N~\4 ci~ies. r241 

Direct measure!'l'ents o! die5el oarticuJ.t'lte levels i!'I 

overall urhan areas have not heen made because of t~e 

difficultv _in _~istinouishina diesel particulate from other 

carbonaceous cartic~late. 'T'he use of a surrogate aocroach to 

relate ni~sel carticulate to so~e otber oollutant which can he 

readilv measured in urban areas apoears to affor~ the best 

chance of obtainina reasonahle estimates oF diesel particulate. 

concentrations, as was the case for urban air auality estimates 

.in the orevious section of ti,is reoort. Of the criteria 

oollutants which 'iave heen assessed hy n"QPS using the NEM. 

methodoloov, ~n apcears to have the most aesirahle 

characteristics as a surroaate for diesel oarticulate. ~t~oscheric rli concentration~ are oeneral!v recoonized as beino 

essentiallv totallv attributahle to mohile sources, whereas 

other automotive oollutants are also e~itted hv stationarv 

sources. The cHsoersion characteristics of en are also verv 

similar to those of cHesel oarticulate :natter, since diesel 

oarticles are found to be relatively fine and are, therefore, 

assumed to ~isperse essentiallv like a aas. 

::'he ro NF.'4 is Clesioned to provine an overall estimate of 

.en .... :oo.ou1.a· .. tci.on ........ e,xoos,u.re-- ·.:r-e 1 a.·ted ... t·o .•. r. .. if-f.e rent ... 11a.1 .. u.e.s .. o.f .tn e .. rn ......... "'-.;.;.:.-. ·:.-.~ 

•.r;A{~~,. _ _.,_._,:.r_h i !..~-. t:-.e- se.l~c t ion; of· CO -a'nd·· ·t-'."-:·e .,r:::.~ · .. :r1e-thodol·oov -"'Fs ~- .~- ··-· .;-,.::: 

oe~~aos t~e ~est hasis for a ~nhile source assessment of 

oooulation ~x-:)osure, a number of rnodificati11ns to the NEV \() 

-:sseo:;s!!'!ent: are necessary and/or desirable in order to orovicie 

~he hest estimate of diesel particulate excosure. 

One modification to the standard N~~ '."'et~ndoloov involves 

,.h,,. re!T'.oval of all indoor sources of CO, sue'."\ as cas stoves, 

from t:-.e air aualitv inventories. ""his c!°'.a":ce allows for a 

more crecise estimate of automotive sources, particularlv 

ine!oors, where the contrihution of outdoor emissions is still 

oresent without the confnundino oresence of indoor sources. 

~his i~ the most imoortant modific~ton to the model in order to 

allow a reasonable estimate of a1Jtomotive exoosure to ro anrl, 

via an approoriate conversion, to diesel carticulate. 
3-21') 

Other desirable modifications to th~ · N~M, which are 

olanned for the. near future, include an effort to correct the 

model for a susoected urderestimation of mohile source 

microscale area contributions, and an effort to desian a 

national extraoolation procedure exoresslv for mobile sources. 

A modified version of the NF.~ methodoloav is exoecterl t~ 

produce slia~tlv ~iaher exoosure levels than the oriainal 

version: however, it -is felt that the current version is 

a~eauate for the ourooses oF this aocument • 

.,,he N~~-hased exoosure estimation methoc1oloav used in this 

reoort orovides hoth an averaae \("i exoosure and ("() exoosure 

distrihution for the four cities in the data hase. ~he averaae 

r.o exoosure results are used to feveloo the nationwide exoosure 

estimates for d iese 1 part icu late i.n l qg c;. .,,he exoosu re 

distrihution form of t!"'.e methodoloav is not essential for the 

uses of this report and will not he presented here. uowever, 

for the sake of comoleteness and hecause t~e distrihutions do· 

oresent information on exposure ranees of ciesel oarticulate 

·which mav hP. interestino in olacino the exposures in 

oersoective, the exposure distrihutions for diesel particulate 

will he presented later in this chaoter. 

~. Past ~xnosure 'l:'fforts 

Before discussino the details of t'.-,e diesel particulate 

exoosure estimate derived in this reoort, it mav he useful at 

this o.oint- to comoare the 'T'l:'Y methodolocv to the aeneral 

methodoloaies used in orevious E?A assessments of mobile source 

oollut3nt exoosures. ,. . ..,o different as~essrr.ents ~ave been used 

in t'.!e oast: 1) one hased on a methoao loav by 0 erlco for a 

qrevious FPA diesel oarticulate risk assessment and, 2) one 

hased. On .. a. methOOOlOOV by"· S·?:"( ~ for. ai"I .. ';_PA,. benzene risk; 

assesS;'!'l@.!"'t • 

.,,h@. Perlco exoosure assess!Tlent 11se<i ari !ir 0ualitv niso1ay 

voneli.na <A.nDM) aooroach wherein the urhan area to be modelled 

was brokP.n uo into a set of ::-eoaraoh ical ar ids where the or id 

oooulation and qrid oollutant concentrations were combined into 

an exoosure for each or id. r 2 51 "'he Pe<ico aooroach used .,,SP to 

~eriv~ the oriainal oredicted concentrations of particulate and 

adjusted these orel'.'lictions hase~ on 'T'~t> · monitor r--levels. 

μowever, since the emission ~attern and amhient ~istribution of 

'!'SP mav ~e verv 1Hfferent from diesel oarticulate riue to tlie 

laroe cnntrihutinn of non-mobile sources to TSt> emissions, this 

is ana was thoua!it to he a source of oossi'"'le error in the 

Pedco assessment. Also, no effort was made to simulate 

cHffeu~nt activitv oatterns as '"as none bv the 'iF:M model. The 

Pence aooroach was aoplied to onlv one citv, ~ansas Citv, ann 

this sinale result was extraoolate~ nationwide. ~he Pedco 
3-21 

apcroach was verv valuable at the time of its develocment as a 

coarse, but usable, first estimate of the cooulation exoosure 

to diesel particulate: however, the cresent "1(='~ mo~el is felt 

to be a more de ta i leci, or ec i se a cpr oach and probabl v, 

therefore, vields a more accurate result. Tt is not oossible 

to ciirectly compare the results of these two appr.oach.es (NF.M 

and Pedco) because· of the different emission factors used. 

~owever, -·it - is estimated that the current NEM assessment 

results in exoosures which are rouohly a factor of. l" hioher 

than those in the Pedco report. At the time of the prenaration 

of the oedco report, and its suhsequent use in the ~PA's 

creliminarv risk assessment for diesels, it was tiiouoht that 

the -Pedco assessment miaht be low, primarily because Kansas 

r.ity was not thouaht to be t~e most typical urban area with 

resoect to automohile emissions. 'T'hus, while this factor is 

sianificant, it is riot unexpected or unusual in our view, hut 

rather indicates that the current 'lFM aoproach reoresents a 

more correct and crecise exoosure assessment for mobile sources. 

,,.,he S?T moneliriq acoroach usea for the t:'PA benzene risk 

assessment esti:Tiatec1 the mobile source contrihution using an 

area wide aisoersion model called the μanna-\.ifford discersion 

!""1oilel.f:?61 'T'his aooroach is very simolistic, reauirino onlv an 

es t i TTI ate o f 3 n · u r ha n a re a ' s v eh i cl e re a i s tr at ions , ~JM'T' , a r ea 

size, averaoe annual wind sceed, and ve~icle emissions. A 

relativelv limited examination of copulatirrn activitv catterns 

was used hv SR! to estimate the influence of the manv different 

sources of henzene, ~ut onlv the area-wi~e dispersion-based 

ave races were used for the automohile contributions. 

(omcarison of the exoosures calculated bv the SRI ~enzene 

assessment to the NF.~ exoosures results in the f inoina that the 'l~~ 'oased exoosures are roughlv a :actor of five hioher t!ian 

,. t",e· ... S?:T· -estimates- .fo·r· -a·· eomoa-r:ab.t·e: e·"''issicon-· factor.·· ·The" SRI--· 

::·reoort•·st·a·t·es· -trra·t -t:l-ie '"autoinohite"" c·offtrihu .. t'io·n: to ·t:-:e~ benz~r1e·-· ...... . assessment are orobah.lv underestimated hecause of the fact that 

the area-wice iT'O~el used mav not adP.cruatelv reflect the l;ich 

localized concentrations believed to occur around 

automohile-use areas. (261 '!he ·relatively .-::lose .=.oreement 

hetween the SRI and N"E:~ excosure assessments and the intuitive 

loaic discussed earlier on whv the NE!'-' should be hiaher leads 

to the conclusion the NE~ model used in this reoort is 9robably 

the most valid aporoach currentlv available. 

C. Averace Sationwic1e niesel Particulate ~xcosures 

~ahJe 3-7 oresents the NFM hased averaae rn concentrations 

for the Four cities used in NF~ oroaram. ~he averaae en 

excosure r.oncentrations for each citv in ~ahle 3-i are co~bined 

in or~er to crovine the desire~ nationwi~e averaae exoosure. A 

5 i:nole methoc1 to use, and tre one used hv ho th the C() NEM an~ 
3-22 

Table 3-7 

Averaae ~otal CO ~xoosure in Four Cities 

Associated Total 

Pooulation Urban Pooulation 

co oom of C"itv As In Cities 200,000 

("itv <Annual 3VO.) rrsec in C0 NF'.~ 1970 

Chicaqo 1. 8 ppm 2,363,014 3 8 , 8 9 4 , 3 6"5 

Los .!1.nqeles 3.0 7,716,895 2F;,339,249 

Philadelphia 1.3 2,933,790 10,553,523 

St. Louis 2.0 1,221,461 17,350,712 

Overall 2.12 93,137,849 
3-23 

this report, oroups each of the larae urban areas in the 

countrv (populations oreater than 200,000) with one of the four 

modeled cities · accordina to overall urban characteristics, 

includina pooulations, vehicle-use oatterns, etc.r241 rrnr1er 

t h i s n a t i on w i c1 e ext r a po l a t ion , a 1 a r a e oo r t ion o f the 

oooulation (43 percent) is grouped under Chicaoo. · While this 

nationwide extraoolation seems reasonable and valid as an 

estimate, it is most likely the least precise part of this 

assessment. ~hus, it is one of the areas that EC~D is 

continuina to investiaate as oart of the onaoino mohile source 

ex~osure estimate oroiect. ~c.,.o intends to use a larae ~ank of 

r.o monitor data, perhaos from the EPA SAPOAD data base, 

selected with a view toward mohile source contrihutions, to 

crovide an extranolation to the nationwide situation • 

.,.he national oooulation (C"olumn 4) in 'T'ahle 1-i, as 

mentionec t:ireviouslv, counts only persons in urban areas with 

co ou la t ions are ate r than ? n O , n n O • Wh i. le i t i s des i r ah l e to 

extend this analvsis to the peculation in all urhan areas, 

inclucHno those with peculations less than 200,nno, the 

li1<elihooci that the exoosures in smaller urban areas would he 

lower than anv of the Four ~~M cities orevents this from beino 

oreciselv done. 'T'herefor~, we have limited our analysis to the 

oooulation!'; in the larae urr.an areas w::.-:~out consideri!"la the 

exoosures of rural or small urban areas. 

'1'he af=orementioned nationwi..,e extraoolation to tr.e N"l='~-CO 

averaae output results in the calculation of an overall averaae 

nationwir1e concentration (hased on C"O) of aooroximatelv 2.1 

com. '1"'his total adjusted national averaae (2.1 com) can then 

he 'l'!anioulated into a diesel oarticulate national averaae bv 

ratioina r:o an~ diesel particulate emission factors, and then 

.. , iiu.LtiolNina ... ·t:-:e.··res.u.lt,····by .,..2 ... 12 · oprn.· .... ,·.'T'·!:·e ~-at-ional · averaa·e c.n,·. · ,;~'"'· 

'e~ is s ion- ':·ac to·t - ·E or r 19·7 8 ··· '( t !"! e .. 'S'ame ··~·-··.;ea· r ··~·s· ' th·e .. 'co ' ~n:·~' "da~t"a~ -··~ ·'. .. , .... , ·:. 

hase) is estimated to be i=i/.1 a/rd. f2il :..70·..iever, since future 

·1ear 11M'T' 1s expected to increase by about js percent, the 

~iesel oarticulate e~i~sion factor should be adjusted uoward hv 

a factor of 1.45 for l9<1c;. [181 The 199S rliesel oarticulate 

e~ission factors are the same as those use~ in the air aualitv 

analyses (see Table 3-2). 

.,.able 3-8 oresents 

cnncentrations for e~ch 

values will he used in 

particulate cancer risk. 

national averaae diesel oarticulate 

of the four main scenarios. 'T'hese 

r.haoter 5 to esti~ate the diesel 

"T"he totnl oooulation exoosure (from 'T'able 3-8) for the 

best esti~ate sales and relaxed standards scenario is estimated 

to he i=il cercent hiaher thari the exoosures calculated for the 

corre~pondina hnse case standards. However, seoaratinq the 
3-24 

rrable 3-8 

Total ~ational Diesel Particulate Exoosur?. in 1Q95 

LDV 

LDT 

MDV/LHOV 

HHDV 

Total 

Annual Averaae Diesel Particulate 

::xoosure (ua/m3) 

Best Estimate Sales Worst ~ase Sales Rel~xed Rase Relaxed Base 

1. '2 3 

0.60 0 • Ii 4 

(1 • 5 4 0.27 

, 

2 . f; l l. 34 

4.98 3 • (19 

2.73 

0.92 

1. 07 

2.66 

7.40 

2.07 

O.R7 

1. 3 7 
3-2 c; 

lieht- and heavy-duty c.omponents of these exposures, individual 

contributions to this increase in exoosure with relaxerl 

standards are 14 percent for LDVs (LDVs and LDTs) and 86 

oercent for HDVs (FDV/LHDV and HHDV) • These data can be 

interoretea as meanina that the bulk of the increase in 

exoosure with best estimate sales and relaxed standards can he 

attrihuted to HDVs with a comoarativelv small contribution from 

LDVs. 

Tf the worst case sales croiections are used to derive 

relationshios hetween the relaxed and hase scenarios above, 

then the overall pooulation exoosure is increaseo 54 oercent 

with ,LDDs 'contributinq 28 percent of the increase, and HDVs 27 

oP.rcent. 

n. ~xoosure nistrihution for Diesel Particulate 

In ancHtion to the nat:i(")nal averaae exposure derived in 

the orevious section,· this rnohile source mocel can be used to 

inentifv a distrihution of exoosures amonq discrete 

concentration raneec;~ A manioulation ·of this information in a 

manner analaeous to the orevious niscussed averaae exoosure can 

he used to orovide a national averaae diesel carticulate 

exoosure distribution. ~or convenience ':his distr.ibuti('m is 

oresented in ,,.,able 3-9 as a ranae of per::F>ntaees for the two 

cities with the lowest and hiahest exoosures versus the diesel 

oarticulate concentration ranee (deoendent on the scenario). 

'T'he exoosure cHstributions included iri .,..ahle 3-9 can be 

used as a relative illustration of how the total exposure is 

~ro'<en nown into concentration ranees. While this data is not 

used furt!":er in this analvsis, in the event that a non-linear 

......... r is'< . moci e.l is ., u.sed i-.n .t.h.e .. fut-u re·-·· to ... est i!Tl.a.te .""t:Hes el ... ca nee r 

.. ~ ·risk·, data'" such as: ·those i:n 'T'able J·-9·"wi·ll· be· necessary- f·or·,·. 

estimatine the ~ancer risk to individuals. 

A brief inspection of the ~ata in "'ahle 1-9 show that 

while there are distinct differences hetween each citv's 

exoosure nistribution, there is the common feature wherein most 

of the diesel particulate exnosures (9~-99 oercent) are in the 

lowest range. '!'he corresoondina ranees of diesel particulate 

exposure are from 0-10 to n-21 ua/m3 neoending on scenario. 

Tf future interest is aenerated on this kind of ex?osure index, 

a wav to further break out the exoosures withi.n this lowest 

ranae.will ~e necessarv and this ~ffort is underway as oart of 

the onaoina ErTO oroiect on develooina a mohile source exoosure assess~ent methodoloav. 
3-26 

Table 3-9 

Diesel Particulate ~xoosure Distribution 

Diesel Particulate (ua/m3) 

Best Estimate Sales Worst Case Sales 

Relaxed Base Relaxed Base 

117-

106-117 

94-1'06 

7()-82 

59-70 

47-59 

35-47 

28-35 

21-28 

16-21 

f') - 1 6 

73-

6fi-73 

58-fin 

51-58 

44-51 

36-44 

29-36 

22-:?9 

17-22 

13-17 

10-13 

0-10 

174- 114-

174-174 102-114 

139-157 91-102 

122-139 79-91 

105-122 68-79 

87-HlS '.'7-i:iA 

70-87 45-57 

52-70 34-45 

42-52 27-34 

31-42 20-27 

21-31 ln-20 

n-21 o-16 

Ranae of 

Pooul3tion Exoosed ~ 

Hiah Low 

Los Anaeles Philadelohia 

0.000654 

0.000345 

1).000941 

0.006804 

0.008965 

n.n3fi916 

0.066520 

n.185011 

0.552863 

l.2q2C!52 

2.825991 

95.022026 

·o. 000250 

0.000000 

0.0002fi3 

n.nn1121 

o.oon555 

0.007867 

0.00942:? 

0.020867 

l'l.084505 

0.194798 

0.414451 

99.265896 
3"."2 7 

VT. Suooort for Air Oualitv Analvsis Used i~ This r~apter 

For ourooses of validation, the followina sections will 

lend suooort to the hasic theories hehind the air auality 

analvsis oerformed .in this chapter. The first section contains 

a review of available historical data on mobile source 

emissions and amhient concentrations of both lead and carbon 

monoxide: the demonstrated similaritv between trends in 

emissions and ambient concentrations offers support for the use 

of the "rollback" theory in orojectinq future ambient levels of 

both lead an~ CO. ~he second section contains a comparison of 

the air qualitv model descrihed earlier in this chaoter to ot~er lead surrooate work contained in a recent ~PA studv. Tn 

this section, both models are used to calculate 1980 ambient 

diesel particulate concentrations for four U.S. cities: the 

similarity in results obtained with the different rnot'.3els lend 

suooort to their validitv. 

"A. ~Talirlation!'; of Rolll---?ck 'T'heorv as AooliPd to Lead and 

rarh0n 'Aonoxirle 

~he theory behind the air aualitv models previously 

described is hased orimarily on the simole "rollback" modelina 

technique. 'T'he rollhack model assumes that a ~rooortional 

relationshio exists hetween emissi0:is and ambient 

concentrations, and uses this orooortionality to project values 

for future years. Recause lead and en were used as surrooates 

for ~iesel oarticulate matter in this chaoter, it is of 

interest to investiaate the ahilitv of rollhack models to 

predict future concentrations of lea~ an~ ro based on emission 

fact("')rs • 

. T:i .. a. r<?ce-nt-·i:-'P."A r:·eoort·· [121, ·data -on·.·t'."ie-·lead ·consumed ·in · .. ,. oasoline·· an·d 6n._,. amhi'erff' Ut'ba'n Tead'"co'nce·n"trai:ioris. for the vea."t's'-. '·: ... 

1975 throuah 1979 were examined. II.. verv strona correlation was 

reoorted, with an r2 value of 0. 99. a..· gr aoh of consumed lead 

versus ambient concentrations is oresented in Figure ~-1. 

~ecause the relationship hetween lead consu:ned in aasoline is 

linearly proportional to lead emitted with exhaust, it is 

concluded that the correlation c1eoictec1 in Fiaure 3-1 can be 

t r an s late a i n to a d i r e ct r e la t ions h i o 'ri e t ·.i e en l ea d em i s s ions 

and ambient urban lead co~centrations. ~vidence of this 

relationship suooorts the use of the rollback theory in 

preciictina future amhient leaa concentrat:ions from !ii!';torical 

aata on lead. 

Tn a second F.P"A reoort f 281, ro 

vears 197n-so (estimated usinq fp,a•s 

were _examined aaai:ist act;.ial ambient 

taken durinq the same period. Fiaure 

emission factors for the ~OBTLE-2 CO!T'puter model) 

3ir auality measurements 

3-2 is a logarithmic plot 
I 

~ 

I • s 

~ ... 200 

1IO 

1IO 

"' 1•0 

z 

~ 

0 

< "' 

0 120 ! 

Q 

"' 

~ 

:> 100 "' z 

0 

c.> 

Q 

< 

.... 80 

-' 

60 

40 

20 

0 

I 

... 

l 

,. 

... 

180 

1IO 

140 

120 

100 

·.~· . '°- --· ...... ·;;.. ·~ 

60 

•o 

.20 

3-28 

Figure 3-1 

AMlllNT UAO CONCINTUTION 

UAO CIMSUMlD IN GAIOl.INI / 

1975 1976 

~..::.... ~: .. - ---~ --~. ,,_--:_ -=-~ ·~·.c:'..~ .. · •.... :. _, ' ·-;. ~·- ··-. . ... " . . -

19n 1978 1979 

CALE!\: OAR YEAR 

-·- . ' 

' 

i9SO 

' ' ' -----

"----· 

1.10 

1.00 

o.to 

0.80 

0.70 

o.so ~ ·. .. r .... .. C 

0.50 s 

,.. 

~ 

l 

0.40 3 

• 

0.30 

Lcild consumed in g~sol!nc (Ou Pont, 19C2l and ambient lc~d con· 

ccntrutions, 1975-19132. lNunt and Ncligiln, 1982). 
- 0. I 2 

OIQ , \ 0 0 

=o. oa 

• 0.06 

• oiQ. 0 ~ 

c: 10. 02 

'-'o.o 

I., 

0-.02 

• 

,.. -. 0 ~ I 

~-.cs I 

I., - • 0 8 Q 

·- 1 0 ... 

. '- -. l 2 

0 

l \l 

I 

:l - : 5 If\ 

• I 9 l' 

.. - . 2 0 _, 

= - . 22 ~ 

:i 2" • - • lj 

::i 

1..1-.26 

~ I 

... .... ... 

~ r 

r 

~ 

i 

~ 

... .... ... ... ... .... ...... ....... ... ... ... ' ' 

3-29 

Figure 3-2 

' ' ' ' ' ' ...... ... ... ' ..... 

' ' ' ..... 

' ' ' ' 

70_7i 'i2-73 7'1.75 76_77· 76.'i~ ,,_,2 i3_,~ '5-'S 11_19 ·;-~o 

Te Qr- 1 

Seco"d 1-11.;i\ 8-

"'o"'" over-oge CC> • 

oLI. •Ol'll.l..or-1, 

• di. I..~ 

----- Ftdll"O\. l..••1.. 

Cr" QC: 1ech.1l"I 

(leel.. ••1.a11.0M1 
~ ... ·. 

1-30 

of the chances from vear-to-year in hoth C:O emission factors 

and ambient co measurernents. The plot neoicts a aeneral 

correlation between the reductions in both carameters: 

therefore, it is aaain concluded· that the rollhac1< modelina 

techniaue is acolicahle to the orojection of future C0 

concentrations based on historical relationships hetween emissi~ns and amhient air aualitv. 

'T'hese findinas are strona in~ications that both lead ant1 

r.o emissions are reoresentative of trenns in amhient 

concentration levels. This ohservation, couoled with earler 

documentation of th~ correlation he tween lead ann CO 

cnncentrations (Section III), leads to the conclusion that 

either of the two are fair candidates for the surroaate 

oollutant used in this chaoter's rolJhack model for estimati:ig 

ambient diesel oarticulate concentrations. 

c. Comoarison of Lead Surroaate ~odels 

,,..his section comoares the air aualitv model 11escribed in 

Section III of this chaoter to other rollback modelinq 

contained in a recent PP~ study. The basic differences hetween 

the morlels are discussed, and calculations are made for four 

n.s. cities usi?ia l:>oth rnonels. '4. comoarison of the results 

suooorts the validity of the nationwide model nevelooed in this 

chaoter. 

Tn a recent studv oerfor:ned !iv EPA's Office of ?.esearch 

and Develooment (ORD) in resoonse to Section /.14 of the Clean ~ir ~ct, lead was used as a St.:rroaate in ;nedictina al1'bient 

automotive oarticulate concentrations for several cities. fll 

Li~e the lea~ surroaate mo6el ~evelooea earlier in this ~c\a bte r'~- -·ORD' s · m_oce1's _rTia k e _us~e ·of·. t ~ e ro1 l b.ack ·· th.eor ·1·: howeve.r, · 

the rn6<iel.s ~iffer. 'in ·-that the O?o studv examined automotive 

natticulate concentrations as a whole, as oooosed to just 

diesel oarticulate. ~lso, the ·o~D studv user1 a baseline vear 

of 1977 in its orojections, while the model cevelooed earlier 

in this chapter is hased on lq75 ambient lead ~ata. 

Models developed in the ORD study[ll use a ratio of 

automotive particulate mass to lead mass in determinina a lead 

emission factor for the baseline vF>ar (1977) ~ this national averaa~ ratio for 1977 ranaes between 5:1 and 8:1, and is based 

on emission data taken from ambient air ~on.itorina sites. 

~sina a 1977 fleet-averaae automotive oarticulate e~ission 

factor of 0.24 a/mi, the resulting lead emission factors for 1~77 ranqe ~etween o.n30 and n.n4A a/~i. Because these 

emission factors are ~ased on amhient data, as oooosed to ~F>hicle exhaust emissions, a lead disoersion fact~r is not 

necessary. ('T'he model develooed earlier in this c,_,aoter uses 
3-11. 

an exhausted lead emission factor of n.12i:;5 a/ll'i and a lead 

dispersion factor of n.43: this translates into actual 

disoersed lead emissions of 0.054 a/mi for baseline vear lq75.) 

Ambient diesel oarticulate concentrations for four 

cities--St. Louis,· Los Anoeles, ~ew Yor~, and ~ansas r.itv 

(MO)--were calculate'd for 19'30 usina a modified ver·sion of the 

monel develooed in tlie OPD stunv. ~he model has the followina 

basic form: 

F, ( D ) 8 n VM'T' 8 0 

C(D)sn = x x C<Ph77 

p ( 0 !"I) 7 7 V~'T' 7 7 

'T'he 1977 lean emission factors are the same as those used 

in the ORD reoort (0.030 and 0.048 a/mi): the 1977 ambient lead 

concentrations used are also those reoorted in the OPD 

study. (11 'T'he remainina oarameters are those derived earlier 

in this chaoter. ~ 1°~0 fleet-averaoe diesel carticulate 

emission factor of n.nsc;2 a/mi was used in the model eauation 

( f r om .,.. ab 1 e 3 - 2 l • '!'he V~'T' a r ow th r a t e be tween 1 9 7 7 and 1 9 8 O 

was estimated at 1.4 oercent[l91: therefore, a factor of 1.034 

wa~ used as the vv'T' ratio in tre equation. Bv substitutina the 

ahove constants into the model equatior., the 1980 ambient 

diesel particulate concentration can be estimated hy a ranoe of 

values: the lower and u~per ~oundaries of the ranee are 

reoresented by multiolvino ·the 1977 amhient lead concenfration 

for each city by factors of 1.19 and 1.90, respectivelv. 

'"r'he' a!)ove calculations were perfor:T1ed for the f'.our 

oreviouslv '1'1entioned cities: 'T'able 3-10 conioares these values 

to t~ose liste~ in. 'T'able 3-3 for each oF tbe cities. For three 

of the four cities, the values oreviously calculated usino the 

.. model ,;!eve .. looec .. in . .this .chaoter ..... i:a1.1 .well wi.t.h.in. the., .. ran.oes o· 

··ca!culafec- wTt'h t!ie moaified· ·oRo·· mo~el. - The c6ncentratiori for\·~·-· .. ~·, ... 

the fourth citv (~ansas ritv, ~0) falls just sliohtlv helow the 

newlv calculated ranae: this could be due to different base 

monitors heino used in the two stunies. 

Overall, the comoarison of results cemonstrates that, 

altl'louah the basic inout to the models may differ in form, th·e 

final concentrations arrived at are fairly consistent. 'l'his 

si,,,ilaritv in results, alona with other cocumented supoort for 

the theories hehind the surrogate aooroach, lends validity to 

the air aualitv ~onel develooed earlier in this c~aoter. 
City 

St. 'Louis 

Los Angeles 

New York Citv 

3-32 

't'ahle 3-10 

romparison of Ambient Concentrations 

ralculated With Two Different ~odels 

1977 Ambient 

Lead Concentration 

( ug/m3) 

0.89 

1.8-4.2 

0. 157 

Calculatea 1980 Ambient 

Diesel Particulate 

Concentrations (uo/m3l_ 

Modified Values from 

ORD ~odel Table 3- 3 

1.1-1.7 

2.1-8.0 

n.S-1.3 

1. 4 

3.0 

1. 2 

Kansas Citv, MO 0.9-1.4 1.1-2.7 () • 9 
Refer~nces - cont'~ 

13. "Characterization of Particulate ~atter in Vehicle 

Fxhaust," Habihi, K., Environmental Science and ~echnoloqv, 

7:223-234, 1973. 

14. "Control of Particulate Lead Emissions from 

r..utomobiles," Cantwell, S., et. al., SAE Paper 720672, May 1Q72. 

l~. 

Exhaust 

1972. 

"Comoosition,. Size, 

Particulates," Ter Haar, 

and 

G. ' 

Control 

et. al., 

of -?..utomotive 

J APCA, 2 2: 3 9 4 6, 

11i. "Nature of Lead in Automohile Exhaust Gas," 

qirschler, D., and Gilbert, L., Architecture and Environmental ~ealth, Q:?.97-313, l0~4. 

1 7 • " Le a <1 i n So i 1 a n d ~J ea e ta t i on 

State Highway With Low Traffic Volume," 

Environmental ?olluti6n, 9:243-251, 1Q75. 

.ll.lona 

ward, 

a New Zea land 

N., et. al., 

18. "The F1ighway 

Ouarterlv ?eoort," Fnerav 

U.S. DnE, DOE Contract No. 

Fuel Consumption Model: Fiahth 

anc Pnvironmental .r..nalvsis, Tnc. for 

DE-AC01-79PE-70032, July 1982. 

lQ. "'!'ransoortation Snerav r:'onserva'=.ion Data 13ook", t<ulo ~. et.al., ORNL Publication 571i5-Edition ~, 1982. 

20. "Feaulatorv .r..nalvsis of 

Particulate Reaulations for 1982 

Liaht-Dutv Diesel Vehicles," U.S. 

SDSB, Februarv 1980 . 

the 

and 

SP.?.., 

Liaht-nuty 

Later ~odel 

OANR, O~SAPC, 

Diesel 

Year 

EC'I'D, 

.. _ ............ --··21. ·· 11 ora,ft · Reoulatorv ·.r...-nal'Vsis ·· ·.;;.·· · ue.avv::.nutv ·· Dieser 

Particulate ?.eaulations," U.S. P.P.~, OANR, O~SA?C, EC'!'!), SDSR, 

nece:riber 1080. 

?2. "-C:stimatina ~obile Source Pollutants in ~icroscale 

Sxoosure Situations," Inaalls, M., EPA-d~0/3-80-021, July 1981. 

23. "A General ~odel for i::stimatina l:'xoosure '1.ssociate<1 

with Alternative NAAQS," Biller, w., et al., June 1981 • 

2 4. "The N"A0S ~onoxide," Johnson, 

December lq82. 

F.xoosure 

T., et 

~odel (NE~) 

al., Draft . r..oolied to Carbon FPA-OAOPS Recor t, 

2~. "Air Quality Assessment of Particulate Emission~ 

from Diesel-?owered Vehicles," Pedco Environmental, Inc., March 

197R. 

26. "ll.ssessment o: ~uman P'xoosure to Atmosoheric 

Benzene," Mara, s., ands. Lee, EPA Reoort No. 450/3-780)1. 
References 

1. "Study 

draft, 

of 

U.S. 

Particulate 

EPA, E~RL, 

F.mi s s ions . From Motor Vehicles,~ 

March 1983. 

ORD, Vo 1. 2, Acpenrhx r, 

2 o II "'f'h e Relationship between Concentration of 

Traffic-Related 

Site," Witz, S., 

Pollutants and ~eterology at a Los Angeles 

et. al., JAPCA, 32:~43-~45, June lqA2. 

3. "Motor Vehicle Frnissions and Atmospheric· Lead 

r.oncentrations in t!:e Los Anceles Area," Pociaan, r-i.; et. al., 

JAPCA, 28:1200-120~, December iqi~. 

4. "Material Ralance for Automobile-~mitted Lead in Los 

Anaetes Basin," f.1untzicker, J., et. al., Environmental Science 

ana ~echnoloay, 9:44~-457, ~av lG75. 

~. "F.~issions and Air 0uality Pelationships for ~tmosoheric rar~on Particles in T,os ~naeles," C'"ass, G., et. 

al., Proceedinas of an International Svmoosium on ?articulate 

rarhon: ~tmosoheric r.ife Cvcle, Plenum Press (N.Y.r.), lq82, 

oc. 207-22Ci. 

~. "An Tnvestiaation of Fut~re Ambient Diesel 

Particulate tevels Occurinci in Larcie ~cale Urban Areas," 

Ueiser, n., ~PA-AA-SDSB-79-30, November l9iO. 

7. "Fstimates of Diesel Particul~te Concentration in 

:'our TTrban ?..reas Ur.der Different ''Ox =-mission Scenarios," rhoc~, David o., et. al., General Motors Research Laboratories, 

SAE oacer ~o. 84041~, February 27, 1984. 

R. "Size-Specific ~otal Particulate Emission Factors 

_ .... ;9 r_ -·~op .~J e _soy q: es_,.~· ... B !".' u e t_~c;l'l, . ~. , . r_~;~s ..... ~PA,.,,, QolN.R,_, .• o~.:..5-·,, .. s.c~"D, '-'- ... ~ ---- -.. ..., .. :-.s~s_-, ~ J. a ri.u.a. _r Y. .l.9 ... 8_4 __ . _ ( ~ r a.f~t) ._ ·-·-. ~-- : ~- .. __ .-; . --·~--·- -__ \-~~ .::;. ..... . .... ~- .... ~---.. :-·~. :. ...... _ .. __ f 

' 

Q, "Particle Size uariation il'1 Diesel Car 

March 1979. 

'E'xhaust," 

Groblicki, P., et. al., SAE Pacer 790421, 

lf1. "'!'he Effect of Operati:i9 Conditions on the Effluent 

of a Wall-Flow Monolith Particulate Trao," ~acDonald, J.S., SA~ 

?acer ~31711, Novemher 1983. 

11. "Diesel ?articulate Emissions," F.~A, P.SRL, Bulletin of ~ew York Academy 

~~:7Q7-811, ~ovember-Decernher 1980. 

Bradow, R., 

of ~edicine, 

rJ. s . 

Vol. 

12. "Lead Criteria Document," Carev, o., Chapter 5: ~ources and ~missions, Fehruarv iqs3, o. 5-13. 
References - cont'd 

2 7 • "~o BILE 2 • 5 F. mi s s ion F' actor 

numbers, ry.s. BPA, 0A~R, OMS, sc~n. 

Proa ram" IJnouhlished 

28. ".l\mbient Versus Predicted 

Wolcott, ~., n.c:. i:-pA, 0~S, 

EP2\-AA-TE~-FF-R2-4, Seotemher 1982. 

Carbon 

~CTD, 

Monoxide Levels," ~FR, Reoort ~o. 
4-2 

Visibility is defined as the areatest ~istance it is 

oossible to see a orominent dark object against the skv at the 

horizon·.r2} ~iddl-eton's Law(2l relates contrast an·d liqht 

intensitv: both are reduced ecrually at horizontal views oF 

obiects aqainst the horizon. !<oschmieder 's Lawf2l aoes a step 

further and relates visual ranae to the extinction 

coefficient. The typical observer can detect a" ob~ect with 2 

cercent contrast aaainst the backaround. f21 'T'he mathematical 

formula aescrihina Koschmieder's Law is: 

1.91 

b ext 

where Lv i s the v is u a 1 ran a e , 3 • 91 is 1 n { . 0 2 ) an c be x t is t~e total extinction coefficient. 

Koschmieder's Law 

Law, which aescribes 

extinction coefficient 

Seer-Lambert taw is: 

Where: 

can he derived· from 

the more Fundamental 

{ bexd on l ioh t 

the Beer-Lambert 

ef feet of the 

intensitv. The 

I 0 = light intensitv at the ohject being observed, and 

I = liqht intensity at a distance L from the object. 

~escribed very simolistically, Koschmieder's Law simply 

states that ohiect~ hecome invisible when the rat.io · o: ! to 

! 0 becomes IJ.02. Substitutina n.n2 for I/! 0 into t!ie 

· Reer:..tambert ·r.aw and ·sol vino for ·L yields Kosch·:nieder·' s ·taw. , ... ·-"-- · ·t-;;. .4. .. • .r ~ ·.•••. ·-' ·~ ·~ .. :· .... ~. ·~·· •• .... • ,:"•r; 'i 

a.s can be seen, the most i!'Tloortant carameter in 

the~e laws is the extinction coefficient (bextl. 

coeff icier.t is the sum of four components: 

1. scatterina by aas molecules, hRq: 

2 • absorption by qas molecules, baa: 

3 • scattering by particles, bso: 

4 • absorotion by narticles, bap· 

all· of 

"T'his 

Diesel carticulate impacts directly on the latter two 

crocesses. In order to oain insiaht into the relative role o~ 

diesel carticulate in liaht attenuation, each of t~e four 

components of the extinction coefficient should be examined. (31 
CHAPTER 4 

VISIBILITY ASSESSMENT 

I. Introduction 

The most obvious effect of diesel particulate, esoecially 

in urban areas, is reduced visibility. In order to study this 

effect, there must he a means of measuring the relationshio 

between diesel particulate and visibility levels. 'A. method is 

needed to determine the visibility impact from a specific level 

of diesel particulate. 

This chaoter develops and ap9lies a method for measuring 

the change in visibility caused by an increase in diesel 

particulate concentration. This is done on a city-by-city 

basis, yielding visibility levels for four regulatory scenarios. 

No attempt is made in this study to estimate the dollar 

value of the ?rejected changes in visibility. Such an analysis 

is beyond the scope of this report. f:'or an economic analysis 

of the benefits of visibility improvements, the reader is 

referred to a recent study performed under contract to EPA[l] 

and other studies in the literature. 

II. ~odelino Visibilitv 

There is no absolutely 9referred method for modeling 

visibility: different measuring techniques are appropriate for 

various times and locations. The three types of 

visibilitv-related indices are: 1) direct measures· of human 

percept ion, 2) measures of 1 iah t intensities, and 3) measures 

of visual properties of air. Using observers to measure 

air?ort visual ranges is an example of direct human perceotion ·~,"~ --'"''. ··-~-rne.asu-rement·.Q···,.T-h-is i-s a, -sub-j:ect-ivec ·m·e-t'hod -w.h.ic·!i ·:ifs ··dd:ff.i-cui,t ·-to · ~ .. -:- · :_,;::_.-·,. ~---convert' to · objective ·-"p'hfs-ical - ?ara:mete.t:s!~ =:- . .- 'T'ltere":?-·exfsts ·-··no 

correlation between the methods of measuring direct human 

·perception and diesel particulate. In measurina light intensities, the relationship between perceived contrast and 

:neasured physical contrast is also a subjective and complex 

one. (Contrast, combined color and brightness scales, and 

blue-red luminous ratios are examples of measures of 

intensities.) Because both of the above methods appear to be 

inadequate for relating the effect of particulate on 

visibility, the third method is, by necessity, the method of 

choice. The measuring of visual properties of air and airborne 

particles can directly relate the particulate matter from 

diesels to a reduction in visibility. 

•l .. ;, .... , 
.. 

... 

.. . . 

,,=-~ ...... , ....... __ _ 

. . 

. 

. 

4-4 

. . 2 

10 10000. . . .~. 

. . . . 

.. .m 

·~ . . 

1000 

.. : 

LO 100 . . . . . . 

... O.l. .. • IO 

F ·. . .. ~ ~ 

.· 

--.-.-.-.. --... -.•. ~ .. -.,---.--.-.-.-.-.. -.-.---.~.~ .. -.-.. -.-.---.~.-.. ~.~ .. . ' • . . I . .. z • . ·a.1 · ·· 1.0 .... .., -~10·. r·e ......... 

.. 

, - .. 

. 

C41cu1ated sc~t::~ing eff~ciency for. a 1og r.o~a1 

aerosol siz~ dis-:;oibtJ~on, se~r:at~c st::r:dard 

c!evia'tion equal to z. as a func-:icn of gec::etric . mass mean radius. Mis tJie fin~ par-:ic1e mass 

.. concent:--~ti~n, bs>' is ~1e sca~'t~ring c~efficie:it, 

. and rgrn ;s l.Jie g2~m=?t-:-ic mass rr:~:n radius. For · referenc~, ~ie right hand aAis is t1e mass concantnti on r~ui red to give a vi sua 1 range of 40 kr.l. 

. . 

p.g 

. 3 

rn 

at 

t - ~,. -,. =a • '-

0:" 

b~P ~ IC 
4-3 

A. Gas Scatter 

'T"he extinction coefficient due to scatterina bv cas 

molecules in the free atmosohere at sea level, known as 

Ravleiah scatterina, is rouchlv 1.5 x ln-5 meters-1: 

values of the extinction coefficient within a few percent of 

this have actually been measuren.f21 If.liaht dearadation were 

due solelv to aas molecule scatterina, then the visibilitv 

would he aooroximatelv 2~0 kilometers bv the ~oschmieder 

formula. 'rhus, scatterina bv aas molecules does not olav a 

major role in observed visibility deqradation. · 

B. r.as ~bsorotion 

~itroaen dioxide ('J02) is the only absorbinc caseous 

soecie oresent in hich enouch concentrations to have a 

sianificant effect on licht absorotion. In optics, No 2 seems 

to he important onlv in olumes, not in the case of a well-mixed 

laver.J21 'T"herefore, absorotion bv cas molecules can be 

niscounted in calculatino the total extinction coefficient. 

r. oarticle Scatter 

Particles with ~iameters in the r=nae of n.1 to l.n 

micrometer scatter liaht with the areatest effectiveness. 

Diesel oarticulate f~lls into this ranae. ~iaure 4-1 shows the 

ratio of mass to scatter coefficient as a Function of particle 

ranius. 'T'he duration of this scatterino effect is orolonaed 

for this size ranee, since such aerosols aenerallv do not 

settle out ~v oravitv and are not removed efficientlv from the 

atrnosohere exceot bv incorooration into clouds and suhseauent 

............ -~ --~, .. . ,,": l ~ .. ~~_(),p"t._.-<> .· ~Jyj}~ s ... ~~!ip~. t.h~ ~-. t;Q.~.v :JTig . .'.-L.~P-~r s i_ss ,_.Jn. ,_t~~---,a t_rn.QsoJ:i~.r.~,,..-· .!= 

•• :. ,.,.,."" ,_ : . ·!;i\,.~. ,.,f o,r ~ .,,.$·.e ~e.r.~ l.. _q.;,. 'ls • L~.1 ,~_ · __ .. -~-~- . -«.'. _ : _ : . 'ec-.: . ..;;: : ~- -: _ ·'!'·· .-: ,---· •·· •=· .. . / :r., ... ,.. - · .~. ,.. 

n. oarticle Ahsorotion 

'T'he most i:'l'1oortant contrihutor to particle ahsorotion is 

<Jr3Dhite carbon: any sub-micron 9articles with a hiah carbon 

content will have a sionificant effect on visibilitv. Diesel 

oarticulate, with its liS-80 oercent carbon content, falls into 

this cateaorv. rs1 

IT!. Visihilitv Fauations 

Once all the factors involved are known, the comoutation 

of visibilitv levels cfoe to a chance in diesel particulate 

level is straiahtforward. .A.ccordi!1a to t~e Koschmieder 

Formula, the visual ranae is inversely orooortional to the 

total extinction coefficient. ~he total extinction coefficient 

{bext) is the sum of the extinction coefficient for the hase 

line visihilitv (b0 ) and the extinction coefficients due to 

absorotion and scatterina of diesel particulate. 
4-6 

Table 4-1 

Extinction Efficiency (A) 

for Diesel Particulate 

Stucv 'A 

Trijonis* (1982) 

Klimisch (1982) 

Roessler and. 

Faxoq (1978) 

Vuk, et al (1976) 

Pierson (1978) 

(m2/a) 

8.4 

8.0 

6.8 

8.2 

8. () 

* 'T'he fioure for Tri~onis is calculated from his extinction 

efficiency for fine elemental carbon, 12 +3 rn2/q, usina 

a 70 oercent carbon content in the <1iesel particula.te. 
4-5 

"T'hus: 

bext = ho + Chap + hsp) 

~he absorption ann scatterinq coefficients are 

orooortional to the mass concentration of ,the diesel 

par t-icu late, b = .a.Mc. '!'he proportion a 1 i tv constant is . called 

the extinction etficiencv, referred to as A. "T'here are several 

values, all _ _in_ a close ranae, for the extinction efficiencv for 

diesel oarticulate: these are listed in ~ahle 4-1. '!'he averaqe 

value, ·a.. = 8.0 m2/a, is used for the concentration of diesel oarti~ulat~. ("T'akinq into account the carbon content of diesel 

oarticulate (aoproximatelv 70 oercent), the extinction 

efficiency for fine elemental carbon is 11.S m2/a.) 

'T'herefore, the oortion of the extinction coefficient due to 

diesels is the oroduct of the increase in oarticulate 

concentration and the P.Xtinction efficiency ~f diesel ~articulate, and the equation for bext hecomes: 

( 1) 

In order to compute oercentaae chances in visibilitv, the 

haseline visibility extinction, b 0 , mu!=it be known. Paseline 

visihilities were obtained from several '!'rijonis 

reports. r~,7,8,Ql '!'rijonis . determif"\e~ the existina 

visihilities from cumulative frequencv distributions of 

auality-checked* airoort observations. ~igures 4-2 and 4-3 

show the ~istribution of median visibilities for various carts 

of the countrv. Visibilitv in the Northeast tP.nds to he rather 

low, with the relative ·humiditv actin9 as the dominatinq 

factor. .,..edian visibilities ranae from 8-12 miles with very ..... -· r-"sm.a.11 .. di ffe..re?:lc.e.s .i~J:L_.me.t-r.o-oo.l.,itan. areas-, dH··ban,/suburhan·· are·a·s-,""' - a:nd' · ·nonu'rba n ""':a if ..... ea."s. - ··~0 r the;' Sou th west, the me·~ 1 an. i1T s i bi 1 i'ty't· ... 

is 30-55 miles in laroe urban centers and 65-80 ~iles ·at 

suhurban/non-urhan locations. One Trijonis reoort rc;1 lists 

:nedian visihility levels at 94 urban/suburban locations 

throuqhout the U.S: another report r91 lists median, tenth 

percentile and ninetieth percentile visibility at 12 

northeastern locations. "'-To data exists for the an nu a 1 j11ed ian 

visibility levels of all the major r_i.s. cities, so estimates 

were made from the median visihilities listed above. 

"T'he baseline visihilities <Lv 0 ) 

extinction accordinq to the formula: 

h = 

0 

are · related to 

* 'i'eleohone survevs were conrlucted at the airoorts to ensure 

that each location had an adeauate set· of vi~ibility 

markers for estimatina visual ranqe, reliable reportina 

practices, observation personnel and. observation locations. 
4-8 

Figure 4-3 

25 

70 

·o'i::::;I' 

1% 

-

Figure 3 ~adian annual ·l PM visibiiities (in miles) and 

visibility isopleths for C.:llifcrnia, 1974-1976. (g) 

,. 

70 
I 

r 

'· ; . 

~ Figure 4-2 

.n • 'j· 

'1 

'' ., 

I, ~t 

'-~; ~I ·:. ,. " ; 

60 

L! !' i' ~~ ----

; :: ... 

90 i ~ 

1,! ~ ----,____ -•-;, 

72 oo----ll 

f& Ou.cd on rhologr•rhlc 

pholo111elry dal1 

Iii Buell on pcphclopiclry d•l1 

., O•scJ on unccrlal" ealrapolallon ot 

vl1lblllly frequency dl,lrlbullon 

. ' . 

~ ., 

u • 

1.5 

f luure 2 NctJlan yearly vfsllJI Illes aud v1sll>lllty lsoplelhs·f~>r suburban/nonurban areas ••. f5l 

I I 
IV. Revised Visibilitv Ecruations 

.A.s described earlier, the Beer-Lambert Law Clescrihes the 

reduction in lioht intensity as a function of distance and the 

extinction coef=ficient of the media. For an object outside of 

the affected area being vi~wed from within the affected area: 

--b L 

r = I e a a 

a 

Where ha is the extinction coefficient existinq within the 

affected area, La is the distance from the observer to the 

limit- of the affected area and Ia is the light· intensitv of 

t!ie object at the limit of the affected area. Ia. is 

descrihed by the equation: 

-b (L - L ) o a 

where L is the total distance between the object and the 

observer. 

r.omhinino the two ecruations vields: 

(-b L - b 0 (L - La)) 

I = Toe a a 

Aoolvilio ..,..rijonis' aoolication of I<'oschmieder's Law, ln(I/I 0 ) 

is -3.0, and solvina for L (now Lv) results in: 

3.0 - (b - b )L 

L ...... a ~. . /L_ ... .a .... - ..... . ·. ~--· ~ _- . -.. ~--:_ = ·- . ' h 0 

.where Lana bare in inverse units, or 

L = v 

18.6 X 10- 4 [miles/ml - (h - b ) L a o a 

"o 

( 4) 

where Lv and La are in miles and b0 .and bm are in 

inverse meters. 

~he term ba can be nerived using 

Surstitutina this into Eouation (4) yields: 

18. fi X l0- 4 (niiles/ml - ~. n fm 2 /cl Meta 

h 

0 

Equation ( 1) • 

. ( 5) 
4-9 

The -orooortionalitv constant of 3.11 in this eauation is 

aoolicable when using airport visihilitv data, as oooosed to 

usinq the 3.91 figure from the Koschmieder formula. r~l Airoort 

data does not adhere to the conditions for applying ·the 

Koschmieder formula hecause natural objects at a qreat distance 

are usuallv small (small obiects need a contrast oreater than 2 

oercent to be seen), and natural objects are never black. ~he 

o~ooortionalitv constant of 3.0 is aopropriate accor~i~~ to 

Triionis, et al. r11 

~o simolifv this formula's units, it may also be expressed 

as: 

-4 18.6 x 10 rmiles/ml 

L fmilesl 

VO 

( 2) 

where the units of extinction are inverse meters and the units 

of visibility are miles. 

~he new visual range caused bv the adnition or subtraction 

of cHesel oarticulate can now he calculated from the following 

exnression: 

l~.6 x l0- 4 fmiles/m1 = 18.~ x ·1n-d [miles/ml ( 3) 

., 

h b + a.arm /al~ ext o · c 

Where: 

is determined usino ~auations (1) and (2) . 

. .. . .. _._..,,~_,.,., ............ :,.~--~·-~:o~~"'e.Ve r· , .. , .... -·t ~·e· ·-·"'a tro"J'e" r "ecru at f o-rr:-::.~·.a 5· siime''s. '.""f!iac~- . s~- ,.,, ... -.. ·.·"1_5_·. _,_,, .··•.:. .... .. . . . · · .............. ·~ .... ext .. · '··c6nstari€ t'?rouahout .. the entire visu'al · · ranae. This is a 

satisf.actorv assumption for the haseline situation (i.e.,· to 

estimate b0 ). However, it may· not be satisfactory to assume 

that the effect of diesel particulate will be constant 

throuqhout the visual ranoe. Th~ ambient concentration of 

diesel particulate will be relatively high in the central city 

and near suburban traffic corridors and will be relativelv low 

outs id e of the c i t y or met r o po 1 it an l i mi ts . S i n c e v is i b i 1 it v 

may ·extend to areas hevond the city or metropolitan limits, 

this effect must be taken into account.. For those cases where 

visibilitv extends hevond the affected area, this· effect mav be 

tal<en· into account by returning to the Beer-Lambert Law and 

recieriving Koschmieder's Law assumina one value of bext for a 

fixed distance (i.e., uo to some limit) and another value of 

hext bevond. 
4-12 

not circular, a reasonable aoproximation to tbe averaae 

distances between the center and the edqe can be derived frorn a 

calculation of a nominal radius from the actual area of the 

metropolitan area, assuming it is circular ·in shape. 

v. Visibilitv Lev~ls 

A. Methoaoloov 

Measuring the change in visibility levels due to a chanae 

in diesel Particulate is deoendent on four factors: 

1. the mass concentration of the diesel particulate, 

2. the extent of this concentration, 

3. the extinction efficiencv of diesel oarticulate, and 

4. baseline visibilities. 

F'or those cases where the visual ranae does not extend 

cast the 1 im its of the affected area, the visual range can be 

calculated from the followina expressions: 

-4 lA.n x in [miles/ml 

bext 

-4r . lR.~ x 10 miles/ml 

Lvo = 2 * + 8.0[rn /ql M 

c 

~·!here r"v is the visual ranee in miles, !.,.10 is the haseline 

visual ranee i:i miles, ;ind M is ··the ··:n-ass·-·concentration ·of·-··,=· . c . . ......... ·•· ,., the"diesel particulate~ in grams per cubic meter. -----· 

For those cases where the visual ranee does extend beyond 

the affected area, the visual range can be calculated from ~he 

f.ollowina exoressions: 

18.6 x 

b 

0 

~ L 

c a ( 7) 

* If the oresencf'! of diesel oarticulate is determined in ter~s of the elemental carbon concentration, then 11.5 

m2/o should be used instead of a.n m2/a. 
4-11 

The terms b0 and Mc can be derived from Equation (2) 

and air qualitv .models, respectively. Only La remains to be 

described. 

La is the tycical distance between the viewer and the 

limit of the affected area. '13efore determinina this distance, 

the limits of the affected area must be defined. Tn the actual 

situation,- the concentration of diesel oarticulate oraduallv 

~alls off until it reaches zero: in the model heina used, a 

constant level of diesel oarticulate inside the affected area 

and no affect outside is assumed. The limit of the affected 

area, La, must be between the point where the actual amhient 

concentration of diesel particulate heains to fall off and the 

co i n t w he r e i t f in a 11 y r each es z e r o . The r e f o re , t !1 e a f f e c t e ci 

area's limit, ~a, is where the actual diesel oarticulate 

level is aporoximatelv half of its cel"ltral citv ievel. 'T'wo 

convenient lil"l'its which could suffice are: 1) the c::itv limit, 

and 2l the metrooolitan area limit. Tt has heen assuiiied that 

the metrocolitan areas and cities were circular to calculate a 

nominal radius. 

'T'he metrooolitan area limits for laroe cities, such as Los 

Anaeles (36 miles) and New York Citv (:?l miles), appear very 

reasonable as diesel oarticulate penetration limits (i.e., for 

r...os Anaeles, La = 36 miles and for New York City, La = 21 

miles). However, for smaller cities, such as Ann .r..rbor, 

Michiaan (15 miles) and Madison, ~isco~sin (20 miles), the. 

metropolitan area limit appears much too laroe. The city 

limits aopear much more reasonable for these smaller cities 

(i.e., 2.6 miles for Ann Arbor and 4 miles .for ~adison). Thus, I 

metrooolitan area limits will be used for the laroest U.S. 

cities and ci_tv limits will be used for the smaller cities. ·- ·-; ·· -, · - -· ··.~ '1'hi s ""w-:H 1---mo re- ·c los·e l v·· ··model"" -the ·····s i'"Z'e-'" o·f · 'the' -a··f f e·cted ' a re as·~,.,-,,· . . .. -- ·. - . . - . . .. . ... - . . . ·-'---· - -- - :- . - .. - . ... . ·.. . .. .' .. ' . --- ·v-ielciino a ··hetter model .. for th'e extent of the actual diesel ·· -

oarticulate concentration level. 'T'o he conservative, the 

ciemarcation between the two will be made at a relativelv large 

citv copulation, 1,000,000, resultina in the use of 

metropolitan area limits in onlv six cases: C:hicaao, netroit, 

Houston, Los Anqeles, ~ew York, and ohiladelphia. 

Now that the limits of the affected area are established, 

the tvcical distance hetween the viewer and the limit of the 

affected area must be determined. 'T'his depends on both where 

the viewer is located and on which direction he is viewina. 

While it is conceivable that a model could be formulated to 

determine the mean viewina distance based on relative 

copulation density and shaoe of the affected area, etc., the 

radius of the metropolitan area or city should ~e a sufficient 

estimate of the typical distance between a viewer and the limit 

of the metropolitan area. While most metropolitan areas are 
4-14 

Table 4-2 

Averaoe Diesel Particulate roncentrations, uo/m 3 

City Size Rest ~stimate Sales Worst· Case Sales 

(?ooulatirm) ~elaxer3 Base ?.e lax en qase 

More t~an 1,000,000 . 4. 4 2.8 6.6 4. 3 

~no,000-1,ono,ooo 3.0 1. 9 4.4 2.Q 

250,000-500,001) ?.7 1. 7 4~1 2.7 

1no,oon-2c;o,ooo 2. s 1. 5 3. ~ 2. 4 
Nhere ~c is the mass 

the affected area, La 

area, and 

-4 

4-13 

concentration of diesel particulate in 

is the nominal radius of the affected 

18.~ x in fmiles/ml 

b = 

o L 

VO 

where Lvo is the baseline visual ranee without the effect of 

diesel oarticulate. 

~. Results 

As described in the orevious section, three pieces of 

information are needed for each citv in order to project the 

effect of diesel oarticulate emissions on its visibility: 1) 

citv radius, 2) baseline visibilitv, and 3) the ambient 

concentration of niesel oarticulate. The baseline visibility 

and the nominal radius were estimated for each citv and 

metropolitan area with ino,ono inhahitants or more. 

The ambient diesel oarticulate concentrations in 1995 for 

various cities were estimated in ~haoter 3 (see 'fable 3-4 of 

that chacter). ~here are four concentration values relatino to 

the four reaulatorv scenarios: 1) best estimate sales, relaxed 

controls, 2) best estimate sales, hase controls, 3) worst case 

sales, relaxed controls, and 4) worst case sales, base 

controls. Aowever, these ambient diesel particulate 

concentrations are not available :or every city with 100,1)00 

oeoole or more. ~hus, the available concentrations were --- ,- .... ·averaae~- -accornina to ·citv···s·i··ze··and-us·ea·--for· those 'cit'fes- ··for·"-~"'·"-"' 

which . 'pro 3 ect ior1s . w~'re'"'· not' ava i'labie-. .. '!F:'e. : four' c i tv-s i ze 

cateaories and their corresoonding averaoe particulate 

concentrations are listed in Table 4-2. 

Aoplyino the baseline visibilities, nominal radii, and 

1995 ambient diesel oarticulate concentrations to the 

aooropr ia te c i tv situation (represented bv ::au at ion f; or 7) 

vields absolute visibility levels in 1995 for each of the four 

scenarios. ~rom these citv-soecific visihilitv orojections, 

the effect of 1995 diesel oarticulate concentrations on 

haseline visibilitv can he estimatea. ~he averaae visibilitv 

re~uction for each citv-size cateaorv and diesel control 

scenario is shown in ~ahle ~-3. 
4-V5 

As can be seen, the visibility impact of all scenarios is 

strongly dependent on city size, with the larger cities 

experiencinq the larger effect. This is primarily due to the 

greater diesel particulate concentrations projected for larger 

cities (see Table 4-2). However, the especially large 

visibility effects experienced by the cities having a 

population of more than one million is also due to their larger 

estimated radii. As was described earlier, the entire ~etropolitan area was assumed to be affected by diesel 

particulate emissions in these instances, where in the cases of 

the three smaller qroupings, only the city proper was assumed 

to be affected. 

With respect to the various scenarios, under best estimate 

sales the relaxed scenario reduces visibility by 4-20 percent. 

These visibilitv reductions are reduced to 2-15 oercent under 

the base scenario. Under worst case sales the visibility 

reductions under both the relaxed and base scenarios are much 

greater, 5-27 percent and 3-19 percent, respectively. In both 

cases, the base scenario removes approximately one-third of the 

visibility reduction of the relaxed scenario. 

VI. Uncertainties in the Model 

The uncertainty present in the methodology used above can 

bias the results in one direction or the .')ther. Although the 

degree of these biases cannot be measured, it may be possible 

to indicate if the biases are upward or downward. This section 

will examine the uncertainties involved in this methodoloav for 

;neasuring the change in visibility caused by an increase in 

diesel particulate, noting the biases. ~ :~ .-7 :.: . ~ ., . _ .... ~ .-\.~.. ... ·-·""'·-.. . -.... 

An average value of 8.0 m2/g for the extinction 

efficiency of diesel particulate was drawn fro'm several 

reports. This value may be a conservative estimate according 

to a National Research Council report.flOl As a larger 

extinction efficiency would yield a greater visibility impact 

due to diesel particulate, the currently ?rojected impacts may 

be somewhat low. 

The proportionality constant of 3.l'l was used in place of 

Koschmieder's value of 3.91 to account for the real conditions 

present when measuring baseline visibilities as opposed to the 

theoretical conditions of the Koschmieder for mu la. Certainly 

this figure is an approximation and varies depending upon 

geographical and climatic conditions, but any resulting bias is 

unknown. 

Diesel particulate concentrations and visibility levels 

were modeled as single values for each city as a simplification 

of the actual situation. These values assumed that all 

individuals in an area experienced id en t ica l levels of a iese 1 
4-15 

Table 4-3 

Average Reduction in Visibility 

Due to Diesel Particulate, Percent 

City Size Best Estimate Sales Worst Case 

(Population) Relaxed Base Relaxed 

More than 1,000,000 20 15 27 

son,000-1,000,000 8 6 12 

250,000-500,000 6 4 10 

100,000-250,000 4 2 5 

Sales 

Base 

19 

a 

~ 

3 
4-17 

This can lead to an overestimate of exposure fo~ some 

individuals (e.g., those living inside the city area border) 

and an underestimate for others (e.g., those living outside the 

city border where the particulate level is assumed to drop off 

to zero). .~lso, visibility is stronqly weather dependent and 

the baseline visib.ility levels took no account of this. 

However, the resulting bias is again unknown. 

VII. Conclusions 

'A. method exists to determine the visibility impact of a 

soecific level of diesel particulate. The necessary input data 

include the ambient mass concentration of the diesel 

particulate, the extent of th is concentration (assumed to be 

the city limit), the extinction efficiency of diesel 

particulate. (a value of 8.0 m3/g is used) and baseline 

visibilities for each city. 

vis i b i 1 i t y 1eve1 s in l 9 9 5 for a 11 U • S • c it i ~ s with more 

that 100 ,000 inhabitants were projected under four regulatory 

scenarios. 'rhe larqer cities showed a greater reduct ion in 

their visibility levels for each scenario. Under the best 

estimate diesel sales scenario, the relaxed control scenario 

resulted in a visibility loss of 4-20 percent, while the 

visibility reduction under the base scenario was 2-15 percent. 

Under the worst case diesel sales scenario, vis ib il i ty 

decreased 5-27 percent under the relaxed scenario and 3-19 

oercent under the base standards. In both cases, the base 

scenario removed about one-third of the loss in visibility due 

to diesel particulate emissions under the relaxed scenario. 
4-18 

References 

1. "Health, Soiling and Visibility Benefits of 

Alternative Mobile Source Diesel Particulate Standards," 

Mathtech, Inc. for U.S. EPA, Office of Policy Analysis. EPA 

Contract Number 68-01-6596, December 1983. · 

2. "Visibility Protection for Class I Areas, 't'he 

Technical Basis," University of Washington, Seattle, Prepared 

for Council on Environmental Quality, Washington, D. C. , Pb-288842, August 1978. 

3. "Heavy-Duty Diesel ?articulate 

Regulatory Analysis," U.S. EPA, Office 

Chapter V, December 1980. 

Regulations, Draft 

of Mobile Sources, 

4. "A Study of Particulate Emissions from Motor 

Vehicles, A Report to Congress," U.S. EPA, Office of Research 

and Development, Bradow, et al., 214 Draft, Section 7.2. 

S. "Characterization of Gaseous and Particulate 

Emissions from Light-Duty Diesels Operated on Various Fuels," 

Southwest Research Institute, EPA-460/3-79-008, 1979. 

6. "Existing Vis ib il i ty Levels in the 

and Shepland, Technology Service Corporation 

Grant No. 802815, SPA-450/5-79-010, 1979. 

U.S.," Trijonis 

for U.S. EPA, 

7. "Impact of Light-Duty Diesels on Visibility 

California," Trijonis, Final Report for California 

Resources Board , Contract No. Al-117-32, 1982. - ,.., ~·~ • -.:-·, .. ··.r.-.:: • .1'"' •- -~ •:,•- - ~ ••• - •• 5.:;.: . • . "-!-:: .,....,..,..,~···~!'~- ..... .,_,... ':."~·- ..... ,.... . ..,_.., ,-: •.!"""·.,~-'"'.:·.:it,,..:·• -~-,'.o.1"!"'.,._ ,.-~.l';::-•T•.1,~.1 .... ,..•~ .. ;:_·;;.p,.,'!-' .££ .: • ·,__,~•:: ... :. ..:...'. ~-.:.~:.-.• "'·:':.-

in 

Air 

··~· . .:::·. . 

·; 'C.: - ... ""iL--· ·''--"'i vf~TSif'U:y .:: .. fn""·'·~fh·e·--·-57,--:u·tffl'.:.ies.t" ·'.~' -~-"h<f~· =::xplora·t:(o-;, of 

the :iistorical Data Base," Trijonis, Atmospheric Environment, 

·Vol. 13, oo. 833-843, 1978. 

9. "Visihility in the Northeast," Trijonis and Yuan, 

Technology Service Corporation for u.s. EPA, Grant No. 803896, 

EPA-600/3-78-075, 1978. 

10. "Diesel Cars - Benefits, ~isks, and Public Policy," 

Final Report of the Diesel Impacts Study Committee, Ass~mbly of 

Engineering National Research Council. 

-. ~ .... 
CHAPTER 5 

CANCER RISK ASSESSMENT 

!. Introduction 

Of the potential health effects associated .with diesel 

particulate emissions, oerhaps the greatest concern has been 

associated with its potential carcinogenic effects. This 

chapter will examine the state of knowledge conc~rning the 

carc1noaenic potency of diesel particulate and estimate ~he 

effect of various diesel particulate control scenarios on an 

individual's lung cancer risk. The non-cancer health effects 

associated with rHes:l PC:_r t icula te .. ~ r.e. examined -in Chapter 6. 

The first ~~ction of this chapter reviews the major 

studies which have investiqated the carcinoaenic potency of 

diesel particulate. The second section compares the results of 

these studies and selects a likely ranqe of carcinoaenic 

potency for diesel particulate. The third section examines 

trap-oxidizer removal efficiencies of suspected carcinoqens 

with respect to total diesel particulate matter and makes 

adjustments to the base scenario exposure estimates (Chapter 

3). The final section combines the carcinogenic potency with 

the adjusted exposure values to estimate t~e annual lung cancer 

risk for an individual under each control scenario. 

II. Review of Major Studies 

'T'he potential carcinogenicity of diesel particulate has 

been examined throuah both human epidemioloaical studies and 

clinical studies on animals and other lower oroanisms. Because 

the eoidemioloo ical data base is 1 imi ted, much weight has had . . _ 

to be-. placed o'n ~b~. _c+J.riic.?J .. , .. §.tud.ies .. ,.'T'hes~_. S'.ltnic..~-l::._:::St4,Q.J:e~'s:··:·:.r,·".:~::':'.·~-·"·:. ... est·i-ma·fe · · the·'.:···-ca·r:c·i.noae:n ic 'oo:tet1cv-' ·-o'P ,.·d'i-es·er ·"·oar t icu late by ~r.~~c<:l'mda'"r"i~nef·'"th~Tr. ·clinical re.sults ·to the clinical results ·of 

other cancer-causing substances for which human epidemioloqical 

data are available. In this section, past and current 

epidemiological studies will first be reviewed, followed by a 

review of the comparative potency analyses. 

A. Eoidemioloaical Studies 

The best means to determine the risk of developing lung 

cancer from a given exposure of diesel particulate is to 

conduct a lonq-term epidemiological study. Such a studv would 

trace the health of several well-defined groups of people who 

were exposed to orecisely known concentrations of diesel 

particulate for known periods of time. Comparable groups that 

were not exposed would also be monitored in order to detect any 
5-2 

differences in cancer rates. The influence of such factors as 

niet, .family history and smoking would be known in order to 

strenathen the validity of the study's findinas and reduce the 

margin for error. 

No matter how close the correct methodology is followed, 

an epidemioloaical study cannot "prove" the absence of a cancer 

hazard. Rather, a neaative epidemioloaical study yields a 

statistical upper bound on the potential potency of a 

carcinoaen unner various assumptions of how the carcinoaen 

affects cancer rates. A sound epidemiological study will only 

indicate that a model with an upper bound risk estimate is 

reaso·n·able "in the absence of cont:r a·ry inf or mat ion n. ( 11 With 

these· limit-ations of an epidemio'loaical study noted, two 

studies of diesel particulates will be reviewed: 1) the London 

.Transit Authority Stuny, which was completed a number of vears 

ago, and 2) the U.S. Railroad Workers Study, which is still 

underway. 

1. London Transit Authoritv 

Of the epidemiological studies com?leted to date which 

specifically examine diesel emissions, the London Transit 

Authority (LTA) Study is generally considered to be the most 

thorough, althouqh it too has significant deficiencies. (2] This 

studv initially examined the luna cancer incidence amona 

different aroups of LTA employees between 1950 and 1954,[31 and 

was later updated to include the years through 1974.(41 Among 

the groups followed were diesel bus garage workers (generally 

h ioh leve 1 of exposure) and design ena ineer s ( aener al 1 v low 

-level of exposur.e) •. . Lung. cancer:----inc-idences were identi·f ied 

from information on. the death. certificates of .those who ,were ~., '"~:-.:.·,~:: ·:;.: .. .;:,:.stJ;.tt:.,~~ ·m:p1 qy~e<r;_·~,b.Y.~ ·~:.the..-; ~r.. 't~~:·: .. tf.~~;.:,t~,-e::;;t: .in\ e.·~ =o:f:· :c:f.~,~~t:~f\ -~ .:~~i~t i-~·he,a.Lt fi..::~:; 

· · retirement records, and the records of transfers to other LTA 

job categories. The study did not continue to monitor the 

health of individuals once thev were no lonaer· employed by the 

LTA. This is an area of potential. bias since cancer typically 

develops several years after initial exposure to carcinogens or 

even after exposure terminates. J 

Other weaknesses of the study include the fact that the 

extent of individual exposure to diesel exhaust was not 

measured. Instead, oarticulate concentrations were simply 

measured inside and outside of selected 9arages on a few 

separate days dur ina the 1950-7 4 observation period. Also, no 

soecific cohort of employees was identified and_ followed 

throu9hout the study. Thus, the potential influence of such 

factors as smoking habits, :nedical history and related 

socioeconomic characteristics is not known. 
5-1 

The study found that the cancer incidence of the highly 

exposed group was actually less than that expected based uoon 

r.reater London lung cancer death rates in the 1950:74 

timeframe. 't'hus, the study concluded that in regard to th is 

study population, no evidence existed associating lung cancer 

to diesel engine exhaust. 

However, this study has been analyzed independentlv by Dr. 

Todd Thorslund of EPA's Carcinogen Assessment Group ·and. Dr. 

jeffrey :~arri~; a member of the Analytical Panel of the 

National Academy of Sciences (NAS) Diesel Impacts Study: 

Committee. Both found that the potential errors involved in 

··-··the -LTA study could have resulted in· a .. sizeable u·nder estimation 

of the carcinoqenic ?Otency of diesel particulate. (1,2] · 

Based on the analyses bv Thorslund and Harris, it is 

possihle that sionificant excess cancer deaths could result in 

the general population even though the LTA study showed no 

excess cancer deaths in the diesel ?articulate exposed group. 

Thus, the LTA study's conclusions for its population cannot be 

translated to the general population. Due to. the ootential 

errors involved and the lack of an upperbound estimate, this 

work has been disqualified from further consideration in this 

study. 

2. U.S. Railroad Workers 

Another epidemiological study is currently being conducted 

by Harvard University to evaluate the possible carcinogenic effect of diesel exhaust in U.S. railroad workers. Data for 

the study come from the o.s. Railroad Board. Components o~ the 

studv include: 1) a retrosoective cohort analysis of ':'\>.,. .... n •'•" •·1• -.,.· Jl'<•tl n .... rJ., · ;•···•••_·~- ..... _. • · _ ..... ~;-,..,,..,; ... ,.··.:•~:: •• ~: •. ,:·:·.··, -:, ;:;_1+.;,, '.t·::••.t• •--~· ·····~· .. ··~·.·~.-,, •••. , •. ··~'!'- ,...,_.,.,~ ·-·· 

. a"pprOX lina tely'.,. 57.,:00:0 ·,male: Ca ilroad: . .-WQ[° ker·s,· "2 r a ··case-cont t. .. 0 .. l<;...v:'. :.:.,,:,·1.:·: 

study of 300 incident lung cancer cases and ~atched controls of 

railroad workers, and 3) actual environmental monitoring of 

worker exposure to diesel exhaust. These approaches will allow 

for quantitative assessment of both level and duration of 

diesel exhaust exposure, and consideration of the major 

confounding factor. (cigarette smoking), thus removing the majo~ 

design weaknesses of the L't'A study. 

The retrospective cohort consists of app~oximately 57,000 

male railroad workers, aged 40-64 in 1959, with 10-20 vears of 

railroad service at that time. These workers were selected 

from job categories having hiqh diesel exposure and an 

appropriate sample of control exposure categories. The massive 

amount of data being generated in the retrosoective and 

case-control studies is currently being analyzed. Air 

pol lu tan ts being monitored in five round-house locations 

include nitrogen dioxide, sulfur dioxide, carbon monoxide, 
5-4 

respirable and non-respirable particulate and its constituents, 

such as sulfates, polycyclic aromatic compounds and other 

orqanic compounds. In addition, fractions of the oarticulate 

sample extracts will be analyzed by mutagen bioassays, such as 

the .a.mes test. .a. au al i tat i ve comparison of automobile diesel 

exhaust with the railroad diesel exhaust will be performed by 

correlating the aas chromatography/mass spectra of the 

polycyclic aromatic compounds of each. 

A pilot study was undertaken to evaluate the feasihilitv 

. of this larger study. The cohort of the pilot study consisted _____ Qt appro~imatelv 2, 500 male_ railroad workers who were between __ t,he ages of 45 and 64, working in 196-7 and who had at leas-t -10 

years of railroad service. ----Of these--workers, 69.8 percent were 

in occupations exposed to high concentrations of diesel 

exhaust. ~he risk ratio for luna cancer in· diesel-exposed 

workers relative to unexoosed workers was 1.42, or a 42 oercent 

increase. However, th is increased risk was not statistically 

significant due primarily to the small size of the cohort. (51 

The larger retrospective cohort study and the case-control 

study are currently in progress and are scheduled for 

completion in the near future; at the time of this writing, no 

formal results have been published. 

B. Comparative Potencv Analyses 

Due to the limited epidemiolo<;7ical data available, 

estimations of the human lung cancer risk from diesel 

particulate have been made usinq a comparative potency method 

developed by EPA. (61 In this comparative potency method, the 

re·s1Jlts of n·on-human laboratory bioassays are used to compare -~- _ ··-. -'--·- .. t.he .. c_a.r~ inogen ic .. and ... mutagen.iq .. _. po.t.eQ<:; i_es .. o t-.-d.ices.eJ_ p_~_r __ t;_~_c_~l.~ te _ .... _ - ·:-·· ~ Tsp"e·c·i-'fic'a:1:l-r, the···pa-r't--i~c·1,e--bound ·-o-rganics)" with- -those·· of-··o·ther" ,_ · 

combustion and pyrolysis products that have been shown by 

eoidemiolooical data to cause lung cancer in humans. ~stimates 

of the human lung cancer risks from exposure to these 

established carcinogens, based on epidemioloaical studies, can 

then be adjusted by the corresponding estimates of their 

potencies relative to diesel particulate to yield estimates of 

the lung cancer risk from diesel particulate. The equation 

used is given below. 

Estimated Human Risk Bioassav Potencv (diesel) 

Human Risk = {carcinogen) x Bioassay Potency {carcinogen) 

{diesel) 

The ratio of potencies obtained from the same bioassay is 

referred to as the relative potency. The unit risk exposure, 

referred to in terms of constant exposure per year, always 

assumes a lifetime exposure. The unit risk is calculated for 

each emissions source in order to have a bas is for compar inq 

carcinogenic potency. 
s-s 

This method~loqy is based on the assumption that the ratio 

of the ~arcinogenic potency of diesel emissions t6 the 

potencies of proven ca re inogen ic products is preserved across 

human and non-human biological systems. Although this 

assumption has not been proven and is a novel approach to risk 

assessment, EPA has determined that the comparat~ve potency 

aooroach is the most promising method available until a 

rei iable epidemiol'o"q ical study focusing on exposure to diesel 

exhaust is oerformed. 

The human carcinogens (comparative sources) selected by 

EPA were coke oven emissions, roofing tar emissions and 

cioar,ette smok·e cond·ensate~ ··-The· mobile source samples selecte_q 

included those from a·· ··HDDE (Cat·erpillar 3304), three LDDVs 

(Datsun Nissan 220C, Oldsmobile 350, and Volkswaqen 

turbocharqed Rabbit), and a gasoline-fueled, catalyst-equipped 

vehicle (Ford Mustang !I). Data from other LDDVs were also 

reviewed and will be summarized later in this section. The 

organics extracted from the particulate emitted from the 

above-mentioned sources were used to determine the relative 

potencies. 

~he comparative sources and the mobile source samples were 

both tested in mu tagenes is and care inogenes is b ioassays. The 

mutagenesis bioassays selected included· reverse mutation in 

Salmonella typhimur ium (Ames test), forward mutation in L5178Y 

mouse llmphoma cells, forward mutation in Balb/c 3T3 mouse 

emb.ryo ibroblasts, forward mutation in C!'iinese hamster ovary 

cells, mitotic recombination in Saccharomyces cerevisiae, DNA 

breakage in Syrian hamster embryo cells, and sister chromatid 

exchange in Chinese hamster ovary cells. The care inogenes is 

~ioassays included oncogenic transformation in . B_alb/~ . 3J'~ 

·· <:;:.el ls ~-,~~"V.,iT~l .. , enh'a'n-c·ernen t .. ·of . 't'C"Clns·f'o·rma t ion.·· :'in=· .i·sy(ia"n ·:··nams'fer .· ·"' ·'' ,.,,~'":~t"· 

·embrvo ·cells, ·and-~·ikfn irH'ti'ation·'·and sk.in carcinogenicity in 

S~NCAR mice. Further details of the study design can be found 

elsewhere. [ 7] 

The potencies obtainea in these bioassays, toaether with 

epidemiological data on the comparative sources, were combined 

to estimate the human lung cancer risk from diesel particulate 

in three independent analyses performed by Or. Jeffrey Harris, 

Lovelace Biomedical and Environmental Research, and EPA. ~ach 

will be discussed below. The analyses differ with respect to 

the choice of bioassavs selected for determin~tion of the 

relative potencies and the choice of comparative source 

epidemioloqical data. 

It should be noted that ~PA. did not conduct new 

e?idemiological studies as part of this approach, but rather 

relied upon existing data. For coke ovens, the work of 
5-6 

Mazumdar[BJ and Land[9] was used, for roofina tar emissions 

Hammond's·(lOJ data were applied, and that of Dell and Peto(ll] 

were used in the case of cigarette smoke. The t-;arris and 

Lovelace analyses relied upon the same coke oven and roofing 

tar data. ~or ciaarette smoke, Lovelace used the data of 

USHEW,[12) Hammond[l3l and Kahn,[141 which resulted in a risk 

estimate similar to that obtained by EPA. qarris did not 

include cigarette smoke as a comparative source in his analysis. 

1. ~arr is 

In addition . to his analysis of the London Transit . Autho,r .. ity Study, - Harris-· conducted a comparative potency 

analysis for the National Ac.ademy of Sciences. [11 The 

comparative source emissions selected by Harris were coke oven 

emissions and roofing tar emissions. Using a linear relative 

model, Harr is analyzed the epidemiological data for coke oven 

and 'roofing tar emissions to obtain estimates of the 

proportional increase in lung cancer incidence per unit of 

cumulative lifetime exnosure to coke oven emissions (0.044) and 

roofing tar emissions (0.015). 

Harris used data from three short-term bioassavs to 

estimate the relative potencies of the diesel {light-duty. only·) 

and comparative source samples. The bioassays used were tumor 

initiation in SENCAR mice by skin painting, enhancement of 

viral transformation in Syrian hamster ~mbryo cells, and 

mutagenesis in L5178Y mouse lymphoma cells. The results from 

these bioassays can be found in Tables A-1 and A-2 of the 

Appendix. Harris then applied these relative potencies to his 

estimates of the proportional increase in lung cancer incidence 

from ~xposure to coke oven and roofing tar.emis~ions. to-obtain. · . ~ estimates- ~of·- the· ·nrooo·rt'.Lo·n·a 1. fncr ea-se i·n -·tuna,.,..,.·c.,.2n-rc·er ·.- inc·iae~nce .· . . . .. ...: .. --·~from expo.'s·u·r~ ... to diesel emissions. . 

Harris' overall estimate was a 0.0035 percent proportional 

increase in lung cancer incidence per unit exposure (i.e., one 

'ilicroaram per cubic meter of diesel particulate for one year 

assuming lifetime exposure). This is roughly equivalent to 1.4 

x io-6 incidences of lung cancer per person per year due to a 

continuous lifetime exposure of one microgram. per cubic meter 

of diesel particulate.* 

* Th-e proportional increases in luna cancer incidence 

obtained by Harris were translated into absolute measures 

of lung cancer incidence independently by Thorslund. (61 
5-7 

2. Lovelace Biomedical and Environmental Research 

Lovelace used two methodologies to estimate the cancer 

risk from exposure to LOO particulate. [151 

The first method assumed that diesel particulate was not 

more mutagenic or carcinogenic than the most potent of coke 

oven , r o o f i n g ta r or c i g a r e t t e par t i cu 1 a t e • F i r s t , the an nu a i-· 

lung cancer risk per person for each of the three carcinogens . was estimated . from the --epidemiological studies of coke oven 

workers, roofers, smokers and nonsmokers using a linear, 

non thr es hold model. Then, the aver age concentration of each 

type of .particulate inhaled over a year was es·timated and used - to estimate the annual unit lung cancer risk per individual for 

these comparative sources. All of these figures are pr es en ted 

in Table 5-1. Lovelace then assigned a figure of 1.5 x lo-6 

lunq cancers per person due to a lifetime exposure of one 

microgram per cubic meter of diesel particulate as an upper 

estimate of the potency of diesel particulate. This fiaure was 

based primarily on the estimated annual unit risks for coke 

oven and roofin9 tar particulate, which are both between 1.0 x 

lo-6 and 1.5 x lo-6. 

~he second method used the bioassay cata develoced bv SPA 

i-o estimate the relative potencies of the LOO and compar.ative 

~urce samples. Like Harris, these relative potencies were 

then applied to the unit risks derived from the epidemiological 

studies of the known carcinogens. 

'1'he comparative sources selected from the EPA work were 

coke oven emissions, roofing tar emissions and ciaarette smoke 

condensate. Urban soot was also selected inde~endently by 

Love l:·ac e as·~· aA-' addt t ion·a-1 ·-comoa·r a t'i v·e source. ·'t'he :nutaae ne s i's'·" ·· ~ - a 

........ b.io'assa'Y"s'·~·use'd ··we·r·e' "the· Ames. a"ss'ay; forward. mutati6'n''"'1n" ChlnEfae.. "' .. : 

hamster ovary cells (HGPRT qene locus assay), forward mutation 

in L5178Y mouse lymphoma cells, and forward mutation in Balb/c 

3T3 mouse embrvo fibroblasts. ~he carcinoqenesis bioassavs 

used were oncogenic transformation in Balb/c · 3T3 cells, viral 

enhancement of transformation in Syrian hamster embryo cells_, 

and skin initiation and skin care inogen ic i ty in SENCAR mice. 

These bioassay data are presented in Table A-3 of the Appendix. 

The overall relative potencies resulting from a comparison 

of the data in Table A-3 are shown in ~able 5-2, along with the 

annual unit risks already presented in Table 5-1 and the 

estimated annual unit risks for diesel particulate resulting 

from each comparison. When only the comparative sources used 

by EPt>. are considered {coke oven, roofing tar and ciaarette 

smoke condensate), the annual unit risk estimates for diesel 

particulate range from 0.07 x lo-6 to 0.6 x lo-6 lung 
5-8 

Table 5-1 

Summary of Inhalation Exposures and Annual 

Luna Cancer Risks for Surroaate Pooulations - Lovelace* 

Study 

Population 

Coke Oven 

Workers 

Roofers 

Smokers: 

(ciaarettes/ 

day) . 

1-9 

10-19 

20-39 

40+ 

Urban 

Nonsmokers 

Rural 

Nonsmokers 

Average Air(al 

Concentration 

of Particles 

(mg/m3) 

3 

1 

2-16 

18-35 

36-71 

73+ 

0.06 

0.03 

Annual Lung Cancer 

Risk x 106 (per 

person, oer year) 

·4000--·. 

1100 

260 

470 

800 

1070 

70 

30 

.. ·-·: ............. -----· ··- ---

Annual Risk 

x 106 

(per person, 

per ug/m, 

oer vear) 

1.-3 

1.1. 

0.03 

0.02 

0.02 

0.01 

1.2 

1. 0 - . 

- -- - .. .·. 

[a] The average air concentration of particles was estimated 

as the total mass of particles inhaled oer year divided bv 

all 0 f the air breathed per year (assumed to be 20 rn3 

per day X 365 days per year). 
5-9 

·Table 5-2 

Lung Cancer Risk 

From ~xposure to Diesel Exhaust Based Upon 

Relative Potencies of Surroaate Substances - Lovelace* 

Surrogate 

Exposure 

.Coke Oven -- Emissions 

Roofing Tar 

Vapor 

Ciaarette 

Smoke 

Condensate 

Urban Soot 

Selected 

Diesel Lung 

Cancer Risk 

Median 

Relative Annual Cancer 

ts~PEae~~e/ (~~~kP~~Q~n diesel ratio) oer ug/m3) 

5 - -1. J .. --

2 1.1 

0.3 0.02 

0.4 1.2 

Estimated Risk of 

~i5aetp~er~~£~a~e 

per ug/m3) 

0.3 

0.6 

0.07 

3.0 

1. 0 

Information on this table was excerpted from Reference 15. 
5-10 

cancers per person per year due to a constant lifetime exposure 

of one microgram per cubic meter of diesel particulate (unit 

exposure)~ When urban soot is also considered as a compirative 

source,· the range increases to 0.07 x lo-6 to 3.0 x lo-6. 

Based on the results of both methods, Lovelace chose 1.0 x 

lo-6 as being the most representative estimate for· the annual 

unit lung cancer risk due t_? diesel particula~.e. 

3. ~nvironmental ?rotection Aaencv (~PA) 

Members of EPA' s Office of Research and Develooment also 

recently estimated. the annual unit cancer risk of diesel 

particulate using a comparative potency method very similar ·t~ 

that used by both Harris and Lovelace;[l6l The comoarative 

sources used in this analysis were coke oven, roofing "tar and 

cigarette smoke. Epidemiological data for coke oven workers, 

roofinq tar workers and cigarette smokers were examined using a 

linear, nonthreshold model to determine the annual unit lung 

cancer risk for each carcinogen. A summary of these risk 

estimates can be found in Table A-4 of the Appendix. 

The relative potencies of the coke oven, roofing tar, 

cigarette smoke condensate and mobile source samples were 

evaluated by a large number of bioassays which have already 

been described. The bioassays used in tI:e final determination 

of the relative potencies were the tumorigenicity bioassays 

involving skin initiation and skin carcinogenicity in SENCAR 

mice, the Ames bioassay, the L5178Y ~ouse lymphoma cell 

mutagenesis hioassay, and the sister chromatid exchange. (SCE) 

bioassay in Chinese hamster ovary cells. The results from 

these tests are given in Tables A-5 and A-6 of the Appendix. 

It should . be n~ ted. that .. the. mobJle ._§O.U. rce _ ari_d. C9'!'Pa r.a .. tjy~ -·-·- ,, .. -· ·s·ou"rce-· sam·oles were·· a1s·o evaluated ·. -i.n · ·a. ~nurnbe·r~, of . additional· - -

b·ioassays. - -rhe bioas·says used in this analysis (and those 

selected in the Harris and Lovelace studies) were selected for 

their ability to produce dose-related effects and t=-.e strenath 

and relevance of the end point being measured. The relative 

potencies are shown in Tables A-7 a~d ~-8. 

Two steps were subsequently followed to determine the lung 

cancer risks for the diesels and the qasoline. vehicle. First, 

the relative potencies in the mouse skin tumor initiation assay 

(Table A-7) were used to obtain the annual •Jnit .risk estimate 

for the. ~issan particulate from the annual unit risks for the 

coke oven, roofing tar and cigarette smoke condensates (Table 

A-4). Second, the annual unit risks for the other diesel 

particulates were obtained by multiplying the annual unit risk 

of the Nissan particulate by the net relative diesel potencies 

of Table A-8, which were based on the Ames, lymphoma and SCE 

bioassays. 
5-11 

The annual unit lung cancer risk estimates resulting from 

these calculations are shown in Table 5-3. Since the organics 

extracted from the particulate were used in the bioassays, the 

risk estimates were calculated in terms of organics and then 

converted in terms of particulate. For the three LDDVs, the 

annual risk estimates per person range from 0.26. x lo-6 to 

0.46 x lo-6 due to lifetime exposure to one microgram per 

cubic meter of particulate. The LDDV with the highest risk 

estimate, the Nissan, was initially selected as reoresentative 

of abnormally high particulate organic mutagenic activity for 

an uoper ranoe value. Although engines of this tyoe are 

reported to have faulty injector systems that result -in the 

high activity emissions, other studies show a number of LDDVs 

with Ames mutagenicity activities above that reported for th-e 

Nissan.(15] Hence the ~issan risk estimate is not unreasonably 

high for a diesel vehicle. 

It is interesting to note that emissions from the 

Caterpillar HOOE had about one~tenth the potency of the LODVs. 

This may be due to two reasons: 1) the particulate from the 

Caterpillar had been stored for more than a year before use, 

and. 2) except for the Caterpillar, all the vehicles were 

operated on a chassis dynamometer using the highway fuel 

economy test cycle (HWFE7). The Caterpillar engine was tested 

on an engine dynamometer and operated at low load conditions (~ode II using a steady-state operation of 2200 rpm and an 

85-pound load), possibly resulting in low activity. oue to 

these non- r epresen tat i ve conditions, the risk estimate for the 

Caterpillar particulate will not be used further. 

Ames test results on diesel particulate samples other than 

those cited iri the above analysis were also reviewed. Major ·· ·· · emo"h"a--s is· wa·s· ·on~·:,l:igh.t•.du ty·· ··diiese l .vehicles·,·· ?art ic-u la r ly ·in···use··:·;:-,;;:-, _ _,,.., .... ·.,. ';,... "a~u'ion'fdb"i't"e''S .. ,.. '."'.!""'fo":··--··~ensure.' ''the"'' 'r"e·p'C-esernt'a''t'iveness e·, ''"c)f""' . efie.:: ..... ·:>'! ':·"'~'. 

above-described results. Due to availability of data, and 

because the TA-98 strain was used in the earlier analysis, data 

for this particular strain were of primary interest. 

Results of four separate studies on the specific mutagenic 

activity of diesel particulate are summarized in Table A-9 of 

the Appendix[l7-201: numbers of revertants per ug of SOF 

(soluble or a an ic fraction) are a i ven for samoles both with and 

without metabolic activation. Means for the specific 

activities range from 0.97 to 13.7 for the non-activated 

samples, and between 2.08 and 8.66 revertants/ug SOF for the 

metabolically-activated tests. 

A. comparison of these supolementary data with the values 

used to determine cancer risk estimates earlier in this section 

shows fairly stron9 agreement. '!'he specific activities listed 
--

Diesel Source 

Nissan[a] 

5-12 

Table 5-3 

Unit Lung Cancer Risk Estimates 

for Diesel Particulate - ~PA* 

Unit Risk Estimates· 

(annual risk/uo/m3) 

Oroanics Particulate 

Volkswagen Rabbit[b] 

o.58 x lo-5 

0.11 x lo-s 

0.16 x lo-s 

o.87 x lo-7 

o.46 x lo-6 

0.30 x io-6 

0.26 x lo-6 

0.024 x lo-6 

Oldsmobile(b] 

Caterpillar(b] 

* This table was excerpted from Reference 16 in which 

lifetime risks were presented. These risks have been 

converted to annual risks by dividing by the ~edian 

·lifespan {76.2 years). 

[a] Based on average relative mouse skin tumor initiation 

activity {Table A-7). 

(b] Based on average relative activity i:1 the mouse lymphoma, 

SCE, and Ames Bioassays {+MA) (Table A-8) • 

.. -.;' . - ~~ , .. 
5-13 

for diesels in the comoar-a ti ve risk study (Table A-5) ave rage 

5.7 and 5.8 revertan~s/ug SOF for the non-activated and 

activated strains, . respectively, excluding the Caterpillar 

data: this compares to overall means of 5.3 and 6.1 in Table 

A-9. A comparison of maximum specific activities shows 11 and 

13 revertants/ug for non-activated and activated samples, 

respectively, in Table A-5, versus 21 and 13 in· Table A-9 

(again excluding the Caterpillar). These maximums support the jud~ment that the Nissan estimates from Table A-5 are not 

unusually high and. are reasonable estimates of maximum 

potencies for diesel vehicles. The close agreement between the 

overall means in both tables add further support for the 

representativeness .of the data used in calculatinq the cancer ~ts~·estimates for "diesel 'particulate and fqr_excl~sion of the 

Caterpillar data. · 

!II. Choosina a Value or Ranqe of Values 

A summary of the risk estimates obtained from the three 

comparative risk studies is shown in Table 5-4. It should be 

obvious from the preceding discussion and a comparison of the 

figures in Table 5-4 that there is no concensus among the 

scientific community as to the carcinogenic potency of diesel 

particulate. The three potency studies differ at nearly all 

possible points: 1) the estimated annual '..lnit cancer risks of 

the known carcinogens, even though, for the most part, the same 

epidemioloq ical data are used, 2) the- non-human b ioassays 

selected for actual derivation of the relative potencies, and 

3) the relative weightinqs given to those bioassays selected. 

In addition, all of these studies rely on the assumption 

that the relative carcinogenic ootencies of diesel '=missions 

and the r.elated environmental --emi.ss i.ons,, ... a.r.e-..... o,r--eser_ved across _ · h·u· ma·,.;. .. ,.-· a n·a· -- · · =n· o. n· ·1...,,m· an · · .. bi· o l. ·og i·:c·a l··-,. "<.-s-·v··s·:·t:e··~m··s· ~·:.~·.:: ·:. ·· "·1 tho·· ··u· ·g· ·h· .... ·t'!i·'i''-":li:'~""''" ,, . ..,. __ ,~,,. ··" 1'1•... • • 11!1· ,;a. ...... ,..... ' ,,;:10 •• ,;,J" •• ~1· •. : ' . ·-:91·11".4 i"•. ... ... •. ~- .... .. • • ~ • :::i 

assumption has not been proven correct, it is the best one that 

cari he ~ade until a reliable epidemiological study focusing on 

exposure to diesel exhaust is performed. 

It should also be noted that all of the comparative 

potency analyses discussed used a linear, nonthreshold 

dose-response model to extrapolate cancer incidence to lower 

doses. While this has been the most widely used model in the 

past, others are gaining mere u~e presently. Figure 5-1 

depicts two typica 1 examples of other models: an infra 1 inea r 

model and a linear, threshold model.[211 Since all the 

exposures simulated in the non-human laboratory tests are very 

hioh to demonstrate effects with small number of soecimens, the 

results must be extrapolated downward to lower, more realistic 

doses. Examining F iqure 5-1, the point common to a 11 three 

models can be taken to be the result of the high-dose 
(a J 

[ b] 

5-14 

Table 5-4 

Summary of tung Cancer Risk Estimates 

Comparative Potency 

Anal vs is 

Harris 

Lovelace 

EPA. 

Annual Risk x 106 

(per person per ug/m3 

oarticulate) 

l.4 . 

l.O[a] 

0:26~_0.46[~r -

~hen the EPA comparative sources were used, the risk 

estimates obtained by Lovelace range from 0.07 x lo-6 to 

0.6 x lo-6. When urban soot was also considered by 

Lovelace as a comparative source, the risk estimates range from 0.07 x la-6· to 3.0 x lo-6. Lovelace chose 1.0 x 

in-6 as being most representative. 

Since the heavy-duty Caterpillar sample is not considered 

representative, the range of risk estimates is restricted 

to the range of risk estimates obtained for the light-duty vehicles. 
5-15 

bioassay. Then, as can be seen, both the infralinear and 

linear, threshold model result in lower, low-dose risks than 

the linear, nonthreshold model. Because of this, depending on 

which model is correct, the use of the linear, nonthreshold 

model could overestimate the cancer risk at lower doses. To 

date, however, the linear, nonthreshold model has been the only 

one applied to diesel particulate emissions.* 

Because of the lack of consensus among the various 

studies, this study will use the ranqe of risk estimat~s 

obtained from the comparative potency analyses of Harris, 

Lovelace and EPA. Referring to Table 5-4, the ran~e of risk 

estimates selected for this analysis is 0.26 x lo-6 to 1.4 x 

lo-6 lung cancers per person oer year due to a constant 

lifetime exposure of one microgram per cubic meter of diesel 

particulate. 

IV. Reduction in Cancer Risk Via Total Particulate Control 

In Chapter 3, individual annual exposures to diesel 

particulate matter were estimated for the relaxed and base 

scenarios (Table 3-8). The reduction in exposure between the 

relaxed and base scenarios reflects projected trao-oxidizer 

efficiencies in removing total diesel particulate (namely those 

of non-catalyzed traps). In the interest of projecting cancer 

risk from exposure to diesel particulate emissions, the actual 

removal of suspected carcinogens should be compared to the 

overall reduction in total particulate mass. 

This section will concentrate on the effects a particulate 

trap has on the soluble organic fraction {SOF) of diesel 

particulate._ It 'is this SOF, _ particula.rly __ th.e,. _ J1e_avi_e_r, .. -., ...... ., .. ;: ·:<;··~·:'. '.~y-C:fr-oca't·frons ,·_ ·. 'tha·t .. is .. usually..: .·asso~_ia~ed ~--with. the . bulk .. ~c)f.~~- .. : ~: :;.:: ::. 

bio-activity; this bio-activity, in turn, is generally 

considered an indication of carcinoqenic tendencies. Part A of 

t!'\is section will evaluate the trap's ability to control SOF 

with respect to total particulate. Part B considers possible 

changes in mutagenic or carcinogenic tendencies of the organics 

with the use of a trap. ?art C will evaluate data from 

previous sections in order to determine a ratio of removal 

efficiencies (SOF to total particulate matter): in turn, this 

ratio will be used to adjust the exposure figures from Chapter 

3 • 

• There is one additional model, the suoralinear model, 

which actually results in a higher, low-dose risk than the 

linear, nonthreshold model: [211 however, its application 

to diesel particulate would be the furthest from being 

established of all of the other models. 
S-1'5 

The data examined in this section were limited to studies 

performed with non-catalyzed, ceramic particulate traps. This 

distinction was made in an effort to examine perhaps the 

"worst" case with respect to carcinogen removal. Non-catalyzed 

traps primarily filter solid particulate matter; heavy 

hydrocarbons can still be in the gaseous phase at the trap and 

can escape and later either adsorb onto the remaining 

__ p~~ti_cl1Jate or remai~_ i_n the gas i:>b~se. Catalyzed traps req~~-e. 

gaseous hydrocarbons preferentially to particulate matter. 

Therefore, the use of catalysts in particulate traps would be 

expected to reduce-- c·a·nc:-er r i"sk-·t:c:> a·n ·even oreater extent than 

they reduce total particulate matter. As the costs of 

non-catalyzed traps are used in Chapter 8, non-catalyzed traps 

were chosetf-lier-e -t6 ··repr·es·e·nt the reduction in cancer risk due 

to· base scenario .. cc)n trol :neasu res. --

At this time, it is important to note that data examining 

various carcinogenic parameters both with and without trap use 

were very limited in their availability •. This study bases its 

preliminary conclusions on existing data only; no new tests ~ere initiated. Some areas of the study (such as soluble 

or a an ics removal) had more oe rt inen t data available than did 

others; therefore, in drawing cone lus ions, more weighting was 

given to these ar~as. ~ew information may become available in 

the future that could modify these results. 

A. SOF Removal !fficiencies 

For a 11 the available data examined, it was found that 

actual emission rates for soluble organics were reduced 

substantially with the particulate trap in place; however, the 

SOF .removal efficiency was, in most cases, somewhat lower than 

__ ...... ;~,- t!1_a_t ,/o_r __ ,"~~,0;~~-~ t:~r-~~e~~ula.;~." r~~-μ-~~-i~.l\~« 9ue. ·:~9.H ~h_~--~- .J?".-1.~~- sgx_ · -·· · ~---e-ffic1ency.,. the· "afte-r-trap SOF as. a percent ·0·f-.-total. mass,,-was-·· 

generally found to be higher than the "before-trap" SOF 

percentage. For HDDVs, average reduction efficiencies for 

total particulate and SOF were 76 and 68 percent, respectively; 

for LDDVs, the total efficiency of 80 percent was somewhat 

higher than the SOF removal of 69 percent. For both classes, 

the efficiency "gap" was approximately the same (8 to 11 

percent). (See Tables A-10 and A-11 in the '4.ppendix for test 

data on SOF emission rates. (22-26]) 

When the actual fraction of soluble organics (expressed as 

a percent of total mass) is examined before and after the trap, 

the "with-trap" SOF tends to be higher than the baseline 

percentage. The increase in percent SOF for the LDDVs is 

substantially higher than that shown with the HDDVs; the SOF as 

a percent of total particulate increased (on the average) by 

23.4 ·percent and 11.4 oercent for light and heavy· vehicles, 

respectively (see Tables A-12 and A-13). (22-26] 
5-17 

Ther~ is one concern related to simply focusing on the 

SOF. The SOF is made up primarily of unburned organics that 

condense or adsorb onto the solid particulate matter: organics 

that do not at ta ch to sol ids remain in the gaseous chase. 

Since the trap removes the 9reat majority of the particulate to 

which unburned HCs can attach, one concern is. that more 

organics will remain in the gaseous_ phase._ This concern was 

addressed by examining available data on gaseous HC emissions 

with and without a trap. In six LO and three HD studies, 90 

percent ·of the data showed either a decrease in HC emissions or 

no change at all with the use of a trap: in all instances 

except one, any increases were less than three percent higher 

than 'baseline data (see Tables A-14 and A-15). Overall, 

gaseous HC emissions were reduced by 12.4 percent and 22.2 

percent {LO and HD averages, respectively). Furthermore, a 

durabilitv test on a LD vehicle (23] showed that HC removal 

efficiencies did not deteriorate· with increased VMT: ~C 

reductions ranged from 12 to 54 percent, with an average of 

33e5 percent {see Table A-16). The overall indication here is 

that particulate traps do not force organics back into the 

gaseous phase: this, coupled with the data showing substantial 

decreases in SOF emissions, leads to a preliminary conclusion 

that the number of cancer-causing organics being released to 

the atmosphere will most likely be signi:icantly reduced with 

the use of a trap. · 

Tn summary, SOF removal efficiencies were substantial in 

al 1 cases, a 1 though generally lower than over al 1 particulate 

removal efficiencies. Related to this, data indicates that 

soluble organic material as a percentage of total particulate 

was slightly higher after the trap than before. Further 

.!:?Cam i_na~,.ion , o L. _t:Jie, __ .Spf ,_,._wi.11 __ ,_.C9Jts .. i.d_e.r .. c:.hal"lge s in. 9.i.o: act~-'? i ty, __ .. ,.,l.'r:'\cc·n•d rela.tedly, can'cer.:·r·isk. - - ' .. - • -.'..L "· " .•. -~. ,,..,,.:. ;., .. , .... ,-.. -• .,-, • '•S .. ..;T-':"'"!:t :-.':.".'.~·'0::':f' 

B. Mutaqenic Activitv 

There are various methods of. assessino the cancer risks 

associated with the SOF of diesel particulate matter. One of 

the most widely-used methods is the Ames test, which measures 

bio-activity in terms of revertants per mass of SOF tested: 

when these values are converted to units of revertants per mile 

or per kilowatt-hour, they are generally considered meaningful 

estimates of the carcinooenic prooerties of the SOF. A second 

metho~ of estimating can~er ri~k ls to examine the temperature 

distribution of the SOF: the focus, with respect to 

care inogen ic i ty, is placed on the heavier hydrocarbons (three 

or more benzene rings), which require higher temperatures to 

vaoorize. A final indication of cancer-risk is the measure of 

benzo-a-pyrene (BaP) emissions: this poly-nuclear aromatic 

hydrocarbon is a known human carcinogen. However, it is well 
5-18 

known that BaP represents only a minor fraction of the 

potential. carcinogenicity of diesel particulate: therefore, a 

change . in the concentration of this one compound may not 

indicate a similar change in overall carcinogenic potency. 

Ames mutagenicity test data both with and. without a 

non-catalyzed trap ·were available for one light-duty diesel 

vehicle and one heavy-.duty diesel engine.(27,25] In general, 

the number of revertants per mile or per kilowatt-hour (LDDV 

and HOOE, respectively) ·was lower with the trap in --place: the 

average reduction for LDDVs was 7.5 percent, while the value 

for HDOEs was 39 .1 percent. The reductions in total 

. part_i~u~ate ma~.s w_ere .-72 _a_n_d_ 8_9 percent, respectively. Thus, 

__ the .!:rap _removed revertan.ts .. 10 and 44 percent as efficiently as - it removed total particulate mass. 

The actual number of revertants per mass of SOF was found 

to increase with the use of a trap: light-duty bio-activity 

increased by an average of 113 percent, while the heavier 

engine had an increase of 170 percent. (See Tables A-17 and 

A-18 for the Ames test data on LDDV and HDDE, 

respectively.) (27,25] 

Boiling-point temperature distr ihutions were also 

available for a light-duty automobile and a heavy-duty engine. 

In both cases, data supported the finding that the particulate 

trap was most able to capture the heavier HCs, presumably 

including the mutagenic, multi-ring hydrocarbons as well. In 

other words, the "after-trap" SOF seemed to contain fewer heavy 

HCs than the "before-trap" SOF samples. 

Actual temperature distribution -data were not available 

. _~ .... ~.~ for . the .... abov:e-,111e n t io_ned. LOOV.: ... , howe•:e.r,., c-ur·V-es for · "w.i·th-" .. and ·-.-· :~n:w1thout":: .. trap w·e·re provided which plotted volatile particu"late 

mass (SOF) versus TGA temperature. (241. The "with-trap" curve 

levels off at approximately 300°C, while the "without-trap" 

curve continues to rise until a temperature of 500°C is 

reached. Therefore, the "without-trap" sample contained more 

materials_ with high boiling ~oints than did the "with-trap" SOF. 

Temperature data was available for a heavy-duty diesel 

coach engine and is given in Table A-19. [261 This boiling 

point distribution of the two SOF samples shows that the 

"with-trap"" SOF has approximately the same · fraction of 

lower-boiling compounds as the "without-trap" sample 

(discounting the initial value), but a lesser amount of 

high-boiling compounds. Again, the data indicate that the trap 

was able to remove some of the care inogen ic, heavy HCs being 

emitted as part of the SOF. 
5-19 

One final indicator of carcinogenic tendencies, the amount 

of benzo-a-pyrene (BaP) , will qe examined for a heavy-duty 

diesel engine and an in-service coach. Data showinq the change 

in BaP level due to trap use are found in Table A-20. [ 26] As 

shown, engine tests showed emissions of BaP to increase by 

0-250 percent, while vehicle tests showed BaP ~missions to 

increase 10-175 percent with the trap. (It should be noted 

that BaP is difficult to measure, and the measurements were 

only 'quoted to one or two significant figures.) 

c. Exoosure to Potential Carcinogens 

Diesel particulate exposure levels for the base scenario 

estimated in Table 3-8 take into account only reductions (from 

the relaxed levels) ·of total particulate mass. In order to 

project cancer risk for the base scenario, the exposure figures 

must be adjusted to take into account the reduction in 

suspected carcinogens relative to overall particulate removal. 

Table A-21 summarizes trap removal-efficiencies for the 

available indicators of carcinogenic potential: SOF, mutagens, 

and BaP. 

·The data show a wide variation between the reduction in 

the three indicators of carcinogenic potential and that of 

total particulate. For several reasons, the d~ta on soluble 

organic emissions were considered the most pertinent. Seven 

independent studies were available and the results were very 

consistent. Overall, the average ratios of SOF removal 

relative to total particulate removal ran<;?ed between O. 7 and 

1.0. The temperature distribution data indicate that the trap 

removes the heaviest oroanics pref e rent ia l ly. Since the bulk 

of bio-activitv is believed to be associated with these heavier 

oraanics, the ·reductio_n .iz:i .~OF _ma_y ac.tu.ally,. \J.nde_res.t.ima.te. the__ .. reduction, ~n .. b.io::act.fv.i:ty. - · : .. . ... · · ··-·· · ·· · .. -........ ., .. "''''" .. '' 

The little Ames test data that compared emissions with and 

without trap use showed inconsistent results. The most data 

was provided by a HD study on a Caterpillar engine {25]: Table 

A-18 summarizes the results. The figures calculated for the 

last four modes are consistent with ear 1 ier SOF reductions: 

excluding the first two modes, the ratio of reduction in 

muta9enic activity with respect to overall particulate removal 

ranges from 0.79-1.0. Ames test d_ata on LD vehicles was very 

limited and not very consistent (Table A-17): the average 

reduction of 7. 5 percent was not representative of previous 

findings, and, therefore, this data was not weighted very 

heavily in calculating the adjusted exposure levels. 
5-20 

There appear to be a number of reasons not to place much 

weight on the BaP data. The only BaP emissions data available 

were from one HD study of a coach engine and coach vehicle. 

The engine in both cases was a DOA 6V-71N, which has unique 

emissions characteristics a~d has already been replaced by the 

6V-92TA or 8V-92TA in transit buses. Also BaP only accounts 

for a. v~_ry small fraction of the overall bio-activitv. Given 

these factors plus the inconsistency between -·the sa:F> results 

and all the other data, very little weighting should be given 

·-to ~hi~·data in determining new exposure levels. 

In summary, the reduct ions in SOF emissions we re - -cons ide-rea- the ·most· represe-rfta t l ve, and, therefore-;-· the- high-est -

· weightirig-·was -given to· results· from these tests.··- In view of 

added support from the Ames test results on heavy-duty vehicles 

and the temperature distribution data, it appears that the 

reductions in SOF emissions should be indicative of a reduced 

cancer-risk. ~owever, since removal efficiencies for the SOF 

are 70-100 percent of that for total particulate, a factor of 

0. 7 to 1. 0 will be used to adjust the base scenario exposure 

levels from Table 3-8. The adjusted exposure levels are shown 

in '!'able 5-5. 

V. ~stimated Risk Based on Projected Diesel Exposure 

The range of potency estimates for diesel particulate 

derived in Section III can be combined with the adjusted 

scenario-specific particulate exposures from Section IV to 

yield estimates of the individual lung cancer risk due to 

d i es e 1 par t i cul ate in l 9 9 5 • After th is has been a one , these 

individual lung cancer risk estimates will be compared to ... cancer.and accidental risks from other sources. £ .... ""!; ••• :J,·:.1~.:..!.·' ·.«:.'.:"""'~";'·!-.• •. -_-. ·.,;.··.:..!. ____ .,;;.._.';;:-..:""': .. ':"'"'7·.;."•_.;;·· l•,-N ... -·-~ .·:·:·-.;:..:_·-· ·_ ... ''.:"''" :- .•• ·; • ·····- -· •••·· ..... -.,..~-·-· 

A. Scenario-Soecific Individual Luna Cancer Risks 

The ?Opulation exposures to diesel particulate from both 

light- and heavy-duty vehicles in 1995 were derived in Chapter 

3 for four scenarios: 1) best estimate diesel sales with the 

relaxed control scenario, 2) best estimate di es el sales wi t.h 

the base control scenario, 3) worst case diesel sales with the 

relaxed control scenario, and 4) worst case diesel sales with 

the base control scenario. Subsequently, in this chapter, the 

exposures for the base· scenarios were adjusted to reflect 

reductions in carcinogens with respect to total particulate 

removal. 

The potency esti:nates of Table 5-4, 

non threshold extra po la ti on model, only 

average individual exposure to obtain 

average cancer risk per individual. The 

based on 

require 

estimates 

projected 

the linear 

the annual 

of annual 

nationwide 

' ~ -
5-21 

Table 5-5 

·Individual Diesel Cancer Risk Projections in 1995 

Projected Individual 

Diesel Particulate 

Exposure in 1995 - (ug/m3) 

Light-Duty 

Heavy-Duty 

TOTAL 

Adjusted Exposures 

Based on Ratio of 

Carcinogen vs. Total 

Particulate Removals 

with Particulate Trap 

(base scenario) 

Light-Dutv 

Heavy-Duty 

TO'!'.;L 

Scenario 

Best Estimate Sales Worst Case Sales 

Relaxed Base Relaxed Base 

1. 8 

'L 2 

s.o 

1. 8 

3.2 

5.0 

1. 5 

1. 6 

3.1 

1.5-1.15 

1.6-2.1 

3.1-3.7 

3. 7 

3.7 

7.4 

. 3. 7 

7.4 

7.4 

--·· - - - .·:-. ,,, . ....... ,.!' ...... ... .... ··1· .. •:• .•. -........ _, ·- :.'• .• ~ .. 

2.q 

l. 9 

4.8 

2.9-3.l 

1.9-2.4 

4.8-5.5 

, ~-!. -~ .r· - .· . !!. : ·:. :: 

Estimated Individual . ·· · Risk··s·a·sed"on A:a.:..:.-.. · ,_. jus.ted oi'esel -·Pa·r·:. ·-.·. '· 

ticulate ~xoosures 

in 1995 X 106 

(lung cancer risk/ 

person-year)* 

Light-Duty 

Heavy-Duty 

TOTAL 

0.5-2.5 

0.8-4.5 

1.3-7.0 

0.4-2.2 

0.4-2.9 

0.8--S.l 

1.0-5.2 

l.0-5.2 

1.9-10.4 

0.8-4.3 

0.5-3.4 

1.3-7.7 

Individual lung cancer risks in 1995 were obtained by 

multiplying the adjusted individual diesel particulate 

exposure in 1Q95 for each scenario by the range of potency 

estimates for .diesel particulate (0.26 x lo-6 - 1.4 x 

lo-6 risk/person-year-ug/m3). 
5-22 

annual average exposure levels for individuals living in .urban 

areas in 1995 for each scenario, expressed in terms of 

micrograms per cubic meter, are found in Table 5-5. These 

exposure estimates are then simply multiplied by the range of 

individual potencies, expressed as lung cancer risk per 

micrograms per cubic meter per year, to obtain the range of 

estimated -i-ndividual lung ca.ncer risk in 1995 due to diesel 

. . 

oarticulate exoosure under each scenario. . 

The resultant individual lung cancer risks in 1995 for 

each scenario are also shown in Table 5-5. Individual lung - - cancer -risks .. in-199.·s due -t.o--exposure .to particulate from both 

-1.ight"'-· and. heavy--.duty. diesels - r,.ange- fr.om O. 8 x lo-6 to 7. 7 x 

lo-6 under the base control scenarios and 1.3 x lo-6 to 

·10.4 x lo-6 under the relaxed control scenarios. 

As can also be seen from Table 5-5, the relative 

contrihution of LDD emissions is much greater assuming worst 

case diesel sales than best estimate sales. Also, the 

individual lung cancer risk is reduced by roughly 27-38 percent 

under the base scenario relative to the relaxed scenario. The 

effect of the base scenario is greatest with respect to the HDD 

contribution. 

B. ~omoarison of Diesel Cancer Risk with Other Risks 

To olace these estimated cancer risks in perspective, they 

can be compared to current (generally 1981) individual risks 

from other sources. 't'he other individual risks Provided for 

comparison include commonplace (accidental) ·· risks of 

death[28-30], ~ost of which would be considered involuntary · · · .' -- (unavoidable), ---a·nd - cancer·, r,isks .c· from-· exoosure to··-· va·r·tous - ··-··· "'sourc"es:-n·a="32r·· Also l.nciu"c:Jed· fs" -the· r°fsk 0

of""aeath fr"()ni Lung ... 

cancer for smokers whose deaths are attributable to smoking, 

along with the risk from lung cancer for the 9eneral pooulation 

whose deaths are attributable to causes other than 

smoking. [33] These risks, expressed as individual cancer risk 

or probability of death per year, are given in Table 5-6. 

Accidental risks are generally applicable to the entire 

U.S. population. As can be seen in Table 5-6, the aggregate 

risk for tornadoes, floods, lightning, tropical cyclones and 

hurrica~es is within the same order of magnitude ·as that given 

for diesel particulate. In contrast, the risks of not wearing 

seat belts, burns, drowning and motor vehicle accidents all 

exceed the risk projected for exposure to diesel particulate. 

The risk of a motor vehicle accident is more than an order of 

magnitude greater than the maximum risk estimated for a iesel 

particulate. 
5-23 

Table 5-6 

Comparison of Risks from Various Sources• 

Sources of Risk 

Diesel ?articulate: 

Best Estimate Sales: 

Relaxed Scenario 

Base Scenario 

Worst Case Sales: 

Relaxed Scenario 

Base Scenario 

Commonolace Risks 

Motor Vehicle Accident[2BJ 

Not Wearinq Seat Belts[29J 

Drowning[281 

Burns[28J 

Tornados, Floods, Lightning, Tropical Cyclones 

and Hurricanes[30] 

Cancer Risks 

Estimated Risk 

(risk/oerson-vear) 

1.3 x lo-6 - 1.0 x io-6 

o.a x lo-6 - 5.1 x lo-6 

1.9 x lo-6 -10.4 x lo-6 

1.3 x lo-6 - 1.1 x lo-6 

222.b x io-6 

112.0 x io-6 

26.0 x lo-6 

21. 0 x lo-6 

2.0 x io-6 

Natural Background Radi- 20.0 x lo-~ 

ation (sea level) (30] 

Average Diaqnostic Medical 20.0 x io-6 

X-Rays in the United 

States[301 

Frequent Airline Passenger 10.0 x io-6 

(4 hours oer week 

Exposed 

Pooulation 

r;rban U.S. 

Entire TJ • S • 

Entire u.s. 

General TJ. s. 

Entire U.S. 

General TJ. s. 

Entire u.s. 

Widespread 

Limited 

f 1 yin g ) [ 3 0 1 -·-

-. Fo.ur .:'aqJes.pq.ons,J~ea_nut ..... ~~ .. ;, .. , ... 8.Q .x, .... LO:_~:· ~·" .,_, -·· .Fa_irly. _.., ... ···-··-'.:. ~ .......... ·- _. ... \. . ... ~_-... ··isu t t\·e r:· -:per Dav · (·d·ue· ··t·o· 't~ ~ '!'" ·"': -~··:::. • · t·1'i~d e·s pr e.a·d, '2.f· ·!· .. ~ :-1 .;<- .:.:·":t 

presence of aflatoxin) [30) 

Ethylene Dibromide{31J 

One 12-0unce Diet 

Drink Per Day[30] 

Arsenic[32] 

Miami or New Orleans 

Drinking Water (due 

to presence of 

chloroform) (301 

Lunq Cancers: 

For Smokers Due to 

S mo k in g [ 3 3 J 

For General Population 

Due to r.auses Other 

Than Smoking(33J 

4.2 x io-6 

2.6 x io-6 

1. 7 x 10-6 

1.0 x io-6 

419.o x io-6 

73.9 x io-6 

~Hdespread 

Widespread 

1% of U.S. 

Southern 

U.S., Urban 

-Sntire U.S. 

* In some cases, an average lifetime of 76.2 years was ---··-... ...; ..... - ... - ............. ,;4=~;mo ,.;c:1r +-n ;an ;ann11.::il risk. 
5-24 

In addition to the accidental risks discussed above, 

cancer risks which result from ·dietary and occupational 

exposures are included for comparison. These cancer risks are 

roughly within the same order of magnitude as that for diesel 

particulate. (The risk from lung cancer will be discussed 

separately.) Exoosures to many of the cancer risks given in 

Table 5-15, including the risk .from diesel particulate, can be 

applied across the general U.S. urban population or a vast 

majority of it. Exposures to the other cancer risks such as ... arsenic, or frequent airline travel, can only be applied to a 

selected segment of the population. For example, only 2.82 

_ mill.io.n people, or roughly l percent of_ the . population are - . 

exoosed by virtue of their occupation to atmosoheric-- -- arsenic. [321 Thus, the number of people exposed to arsenic is 

far less than those exposed to diesel particulate and the other 

cancer risks whose exposures can be applied across the general 

U.S. population. The number of people exposed to each source 

should be taken into consideration when making direct 

comparisons of risk. 

In some cases, risks resulting from certain occuoational 

expo'sures far exceed those risks presented in Table 5~ 6. For 

example, exposures- to arsenic results in an individual annual 

risk of respiratory cancer as high as 180 x lo-6 for those 

few workers exposed near cot ton gins. [ 3 2] For ethylene 

·dibromide~ cancers can result from both dietary and 

occupational exposures. The risk from dietary exposures to 

ethylene d ibromide is given in '!'able 5-6. The occupational 

risks of cancer resulting from inhalation of ethylene dibromide 

vapQr can be as high as 5.2 x io-3 for citrus warehouse 

laborers. [311 .-: .. .: . ~ ... . ::...~- -. ..:· ___ ,.. ~- -- __ -, _·- - -·~'t. :~-- -: •• - • • • - • •• 

·-'The· -i:--lsk· ·-of -rung· cancer. 'for·· smoker_s .... who-se cfaath·5·---a·re 

attributable to smoking, along with the risk from lung cancer 

for the general population whose deaths are attributable to 

causes other than smoking, are also included in Table 5-6 for 

comparison. The maximum lung cancer risk given for diesel 

particulate is roughly 2.5 percent of the lung cancer risk for 

smokers whose deaths are attributable to smoking, and 14 

percent of the lung cancer risk for the general population 

whose deaths are attributable to causes other than smoking. 

The analogous figures for the minimum diesel exposure are 0. 2 

percent and 1.1 percent, respectively. As can be seen, smoking 

is the primary contributor to lung cancer deaths in the U.S. 

( 8 5 pe r c en t ) • 
5-25 

References · 

1. Answer to the Posed Question: Are the Results 

Obtained in the London Transit Worker Study Sufficient to 

Dismiss 'Any Concern Regarding the Potential Cancer Hazard for 

the U. -S .. _. Population in the Future, Due to Diesel Engine 

Exhaust?, EPA Memo From Todd Thorslund, Carcinogen Assessment 

Group to· Michael Walsh, Mobile Source Air Pollution Control, 

January 29, 1981. 

2. "Potential Risk of Lung Cancer 

Emissions," Harris, J., National Academy 

D.C., 1981. 

from Diesel Engine 

Press, Washington, 

3. "The Health of the Worker," British Journal of 

Industrial Medicine, Raffle, P., Vol. 14, pp. 73-80, 1957. 

4. "Trends - in Lung Cancer in London in Relation to 

Exposure -to -Diesel -FU.ri\es·,·-.. In: Heal th--Eff ects -of Diesel Engine 

Emis.sions: Proceedings of an Internationar Sympositim, waller,· 

R., Vol. 2, EPA-600/9-80-057b, 1980. 

5. "Lung Cancer and Occupational Exposures to Diesel 

Exhaust: A Pi lot Study of Railroad Workers," Schenker, M. B. , 

T. Smith, A. Munoz, S. Woskie, and F. Speizer, Draft Submitted 

for Publication, 1982. 

6. "A Suggested Approach for the Calculation of the 

Respiratory Cancer Risk Due to Diesel Engine Exhaust·," 

Presented at the EPA Workshop on the Evaluation of Research in 

Support of the Carcinogenic Risk Assessment for Diesel Engine 

Exhaust, Thorslund, T. W., February 24-25, 1981. 

7. "Mutagenic and Carcinogenic Potency· of Extracts of 

Diesel and Related Environmental Emissions: Study, Design, 

Sample Generation, Collection and Preparation," Environ. 

- International·, Lewtas, J., R. L. Bradow, R. H. Jungers, B. D. 

·- ., :~.~.,Harr.is_!.:• c·R ., .. , .. 8.-. ,. Zweiqipger ,_ .. K .... !1.'..,_. <;;us.l'JAI1g, .B_._ ., E. ,. Gi 11 ._a!_1d .. _R. "'. E, ........... ~_;:, _ .. · ... .,..":'.'-~A lbe·rt ~· .::·V'01 ~·· ·~ 5· ;· pp .·· .... 3··5 3·~3 a·7 -,·· ... '19 81 ~ ·.:.· · '.~·".• .. ~ .. ·~·.: ··~·· .··.:·· ~: ·. "·~ ... ···~~ · .. \"'.:-::-~~ .. -: ·~._ '.vf"<"·";" • • .... ,..,, 

8. "An Epidemiological Study of Exposure to Coal Tar 

Pitch Volatiles Among· Coke Oven Workers," Journal of Air 

Pollutant Control Association, Mazumdar, S., C. K. Redmond, W. 

Sollecito, and N. Sussman, Vol. 25, pp. 382-389, 1975. 

9. Presentation at OSHA Hearings· on Coke Oven 

Standards, Land, C. E., 1976. 
5-26 

10~ "Inhalation of Benzo-a-pyrene and Cancer in 

Ann. NY Acad. Sci., Hammond, E. D., I. J. Selikoff, 

Lawther, and H. Seid.man, Vol. 271, pp. 161-124, 1976. 

Man," 

P. L. 

11. "Cigarette Smoking and Brochial Carcinoma: Dose and 

Time Relationships Among Regular Smokers and Lifelong 

Non-Smokers," L Epidemiol. Community Health, Doll, R. and R. 

Peto, Vol: 32, pp. 303-313, 1978. 

12. "Smoking and Heal th: A Report of the Surgeon 

General," U.S. Department of Health Education and Welfare, DHEW 

Publication No. (PHS) 79-50066. 

13. "Quantitative Relationship Between Cigarette Smoking 

and Death Rates," Nat 1 .. Cancer Inst. Monogr. , Hammond, C. E. , 

Vo 1 . 2 8 , pp . 3 , · 1 9 6 8 . 

14. "The Do:r;n Study of Smoking and Mortality Among U.S. 

Veterans: Report on Eight and One-Half Years of Observation," 

Kahn, H. A., EPT-Demiological Approaches to the Study of Cancer 

and Other Chronic Diseases, Haenszel W. , Edi tor, Nat 1. Cancer 

Inst. Monogr, Vol. 19, pp. 1, 1966. 

15. "Potential Heal th and Environmental Effects of 

Light-Duty Diesel Vehicles II," Cuddihy, R. G., w. c. Griffith, 

C. R. Clark, and R. o. McClellan, Lovelace Biomedical and 

Environmental Research Institute, Inhalation Toxicology 

Research Institute Report LMF-89, 1981. 

16. "A Comparative Potency Method for Cancer Risk 

Assessment: Application to Diesel Particulate Emissions," 

Albert, R. E., J. Lewtas, S. Nesnow, T. W. Thorslund and E. 

Anderson, Submitted to Risk Analysis, 1982. 

17. "Final Report on the Study of Diesel Particulate 

Traps at Low Mileage," Land.man, L.C., and Wagner, R.D., U.S. 

EPA, OMS, ECTD, August 1983. 

•••--• --.- • •·-····,.·ai-o• -~ -·~ ··~··-• • ., -:-·-H- .. • • ·-·. - • .·••._::.••: .•-·•::- .. ·· ... ''"':-"""'"·"'=::.::;~~-~ o•''•', .·.··-·· .... ·.- ~- O••- • 

~ ... ---- . rs~ :::.-:~-:~'The --Eff-ec-t---:of ·-Arumina:_coated Meta-1 Mesh Fi 1 ter -·on 

the Mutagenic Activity of Diesel Particulate Emissions," 

McMahon, M.A., et. al., Texaco, Inc., SAE Paper No., 840363, 

March 1982. 

19. "Analysis of Particulate and Gaseous Emissions 

from In-Use Diesel Passenger Cars," Hyde, James D. , et. 

New York State Department of Environmental Conservation, 

Paper No. 820772, June 1982. 

Data 

al. I 

SAE 
. .. . ..... .. 

5-27 

20-:- "Characterization of Automotive Emissions by 

Bacterial Mutagenesis Bioassay: A Review," Claxton, Larry D., 

U.S. EPA, GTD, EPA-600/J-83-096, 1983. 

21. "Assessment ·of Technologies for Determining Cancer 

Risks from --the Environment," Off ice of Technology Assessment, 

June 1981. 

22. "Diesel Exhaust Treatment Devices: Effects on 

Gaseous and Particulate Emissions and on Mutagenic Activity," 

Gorse, Florek, Young, Brown, and Salmeen, Ford Motor Company. 

23. "Diesel Car Particulate Control Methods," Urban, C. 

(Southwest Research Institute), Wagner, R. and Landman, L. 

(U.S. EPA), SAE P_aper No. 830034. 

24. "Effect of Operating Conditions on the Effluent of a 

Wal 1-Flo~. _Mono 1 i tfi ___ Particulate Trap," MacDonald, J. , GM, SAE. 

Paper .No .. 831711, November 1983. 

25. "Study of Aftertreatment and Fuel Injection 

Variables for Particulate Control in Heavy-Duty Diesel 

Engines," Michigan Technical University, U.S. EPA, 

November 1982. 

26. "Emission Characterization of a 2-Stroke Heavy-Duty 

Diesel Coach Engine and Vehicle With and Without a Particulated 

Trap," Southwest Research Institute, U.S. EPA, May 1983. 

27. "Study of the 1985 Light-Duty Diesel 

Standard,'' submitted to U.S. EPA by Ford Motor 

October 2, 1981-·(EPA Docket A-81-20, II-3-24). 

Particulate 

Company on 

28. The World Almanac and Book of Facts 1983, New York, 

New York, 1983. 

29. "Rediscover the Safety Belt", U.S. Department of 

-Transportation, Nat-ional ··Highway· Tr af·fi·c Safety Administration;···"-.... ~ .. . JJ1983"'." .":-:- ·•;;_.,.:~ -"~- -. .--::-.--. ...... : . " : . -·: .. ~:.).~ .... '. ,. ........ , ........ ::.-. .... ·"" ·"" , ... . 

30. Risk/Benefit Analysis, Wilson, R., and E. Crouch, 

Cambridge, Massachusetts, 1982. 

31. "Ethylene Dibromide: Position Document 2/3", 

Special Pesticide Review Division, Environmental Protection 

Agency, EPA/SPRD-81/74, 1980. 

32. "Final Risk Assessment on 

Assessment Group, Environmental 

EPA-600/6-81-002, May 1981. 

Arsenic," Carcinogen 

Protection Agency, 
5-28 

33~ Estimates for total lung cancer deaths in 1981 

obtained from the National Center for Health Statistics, 

Department of Heal th and Human Services. Percentages of lung 

cancer deaths attributable to smoking and other causes obtained 

from Clearinghouse on Smoking and Health, 1982 Report on 

Smoking and.Health. 
t. Introduction 

CHAPTER 6 

NON-CANCER HEALTH EFFECTS OF 

DIESEL PAR~ICULATE 

One of the primary concerns regardin9 diesel particulate 

is its potential for adverselv affecting human health. The poten~ial adverse health effects of this material can be 

divided into two broad categories: 1) carcinoqenic and 2) 

non-carcinoqenic, or non-cancer. 'T'his chapter deals 

specifically with non-cancer health effects. The potential 

carcinooenic effects of diesel particulate were already 

discussed in Chapter 5. 

Althouqh a larqe amount of information documentinq the 

adverse health effects of inhaling particulate matter is 

availahle in the literature, comparatively little deals 

specificallv with diesel particulate. However, concern over 

the ?Otent iallv adverse heal th effects of exposure to diesel 

exhaust has recently increased, and has resulted in a 

sionificant amount of new research concerninq diesel 

particulate and its effects on health. [1,2) Unfortunately, 

because much of the aiesel particulate health ·effects 

information which is available is comparatively recent and has 

not been peer reviewed by other scientists, very few conclusive 

statements can be made regarding the health effects of diesel 

?articulate exposure. r31 Therefore, at this time, the best 

aporoach for evaluating the non-cancer health effects of diesel 

oarticulate is to evaluate the health effects of particles for 

which established literature is available. However, before 

outlininc how this comparative analvsis will be, performed, it 

is iMportant to describe three t~ings this analysis will not do • 

.. , , . _ First-, th~-·-fa~'t_~::,.t.ka··t · ·partlcles \n~----t-he:- ambien.t air can. 

cause adverse non-cance~ health effects will not be established ~ere. It has lonq been recocnized that exoosure to various 

forms of particulate matter can cause a wide variety of adverse 

non-cancer health effects. The~e effects have heen well 

documented in the literature and total suspended particulate 

matter was among the first airborne pollutants to have a NAAOS 

established by EPA in 1971. 

Second, in evaluating the documented non-cancer health 

effects of particulate matter, the focus will .not be on any 

speci.fic tyoes of particulate, hut rather on typical ambient 

mixtures of particles. Obviously, some types of particulate 

affect health differently than others. For example, soluble 

Particles may affect health through different mechanisms than 

insoluble particles. Some specific oarticles also are 

inherently more danqerous than others (e.g., radioactive 

material) • μowever, because it is qenerally imooss ible 
6-2 

epidemioloqically to ascrihe the adverse health effects of 

ambient. exposures to anv specific comoonen t of the part icu late 

mixture, the effects o{ soecific particles are less important 

than the effects of typical mixtures of particles found in the 

atmosphere. 

'l'h.ird, .this . comparative analysis will not be conducted 

quantitatively, but qualitativelv. While a few quantitative 

health effects studies based on measurements of total suspended 

particulate or British smoke shade are available, the 

extraoolation of these results to diesel particulate could only 

be based pr:L auaJJ1:ati_ve _rel.at.ion.ship.s. and._ the. quantitative. 

-resuifs woula imply a degree of preci.s{on beyond that which was 

defendable. 

Proceeding to the description of what will be done, the 

comoarative analysis will be performed on two levels: 

particulate inhalation characteristics and laboratorv health 

effects testing. The available inf or mat ion on each of these 

levels wi~l be oresented first for ambient inhalable 

oarticulate and second for diesel Particulate, with a 

comparison of the-·two-seEs-of-results ·following on- each level • 

.a.n overall asessment will then be made as to whether or not 

cHesel oarticulate shoulc1 be exoecteci to affect health 

(non-carcinooenically) disoroportionate to its impact on 

ambient mass particulate levels. 

I!. "Jon-Cancer Ffealth Effects of '!'voical Particulate Matte·r 

A. !nhalation of Particulate ~atter 

--- .:: .-::, ..:.:::-:-::;- .:::-.- ., i:.cOn e.,_~o L .. t b.e-.mos.t ea.s,i l-v.,. ··U n.d.e.r,st-o.o:c1z-:,,d e·ter:n·i"nant s.: ·o.f .. a·dv·e-.r: se .._,_*""''~-

' " -nea 1 tli effects· .. f r·om _: .. i nha'.l: i:ncr ~part rcu·]:a te ,_::m·a t-i:"e r ·. i"s: the ·. "body I -;.; 

dose. II For. the·-·-ourp6se"s of th i"s -chapter, the b1portant aspects 

of body dose are: 1) where particles are deposited in the 

respiratorv tract, and 2) how these particles are cleared from 

the system by natural defense mechanisms. Therefore, some 

oeneral knowled<;re reaarding the structure of the respiratory 

tract, in addition to deposition and clearance within the 

system is a prerequisite for specificallv discussinq the 

non-cancer health effects of particulate exposure. 

~he orincipal features of the respiratory system are 

deoicted in Fiaure 6-1. The upper respiratory tract begins 

with the nares (or mouth during oral breathina) and ends at the 

entrance to the trachea. ~he lower respiratory tract is 

subdiviaed into the conductinq airways (or tracheobronchial 

re9ion) and the aas-exchanae region (or alveolar reqion). .'T'he 

tracheobronch ial reg ion cons is ts of the trachea down to the 

minute terminal bronchioles. The alveolar reqion includes the 

oartially alveolated hronchioles and finally terminates with 

the alveoli themselves. (A more complete description of the 

respiratorv ·tract as it relates to particle ~eposition can be 
" .. ~· . --~.-:: _.., .. 

.. 

.. 6-:-3 

Oiagrarrrr.atic Representatioo of the 

H\m'.an Uot:e.r and !.ewer P.esoiratory Tract(4] 

I.~ 

lf'Olfl!OI"\' 

trK'\ 

. .. 

• l 

I 

p 

i 

" ; 

'; 

.... • 

. •• ·' • to ••• • 

~ 

I 

l 

I 

i 

I 

''"I '. .. 

I 

~·. . .. . . . ' .. ~ . l. • ..: • .,;•"1 ..... 
6-4 

1. Deoosition in the Resoiratorv Tract 

a.s stated above, the health effects associated with 

particulate matter in the respiratory tract are dependent, to a 

lar<:Je degree, upon ·where in the tract deposition takes place. 

Spatial deposition within the rest?iratory system is primarily ·· ·· aetermined by particle size, with the mode of breathing ·(nose 

versus mouth) also hav ino a substantial e f feet on the 

disposition of large particles~ 

"1ov i ng through the respiratory tr act, aepos it ion in the 

upper- respiratory tract -during ~ breathing is nearly 100 

percent complete for particles with diameters larger than about 

10 micrometers and declines to about 10 percent for particles 

with diameters less than 1 micrometer. [51 Duri~o mouth 

breathino, deposition in the uoper respiratory tract -is less 

efficient, althouah the vast majority of laroe particles are 

still removed in this region. 

~ost particles smaller than about in-ls micrometers enter 

the . lower respiratory tract. and are deposited, to varying 

<1earees, in the tracheobronchial and alveolar reoions as shown 

in Fioure 6-2. In the tracheobronchial reqion, deoosition 

nurinq mouth breathing is especially hiah for particles with 

diameter_s of 5-10 micrometers (up to 80 percent removal) and 

ta-pers - of-f_ -to--.~ deposition of about 5 percent for particles 

witfi d-ia-me·t-er-s·---of 0.1:..1 micrometers. Deposition of 5-lo· 

micrometer. oarticles in this reoion during nose breathing is 

considerahly less due to their previous depos1t1on in the upper 

respiratory tract. 

~ ·· :"< ... ,_. ~ ~::'="·:i'·;;;·_,,:~~ .-··· -~ffi":T-"Ene :-:·-a1.V:-eoTar-·::>"r-egTon·, .. ,.-aep-o-s1·t~i'on i·s- .. a:trijo·st: !10-iiexistenJ: · ... ,,,,_ - -----. ·-·-----f'o'r·-oa-rt1cles·--w'lth aramet_e.r's 'qr'eafer -than· abouf lb m'icro'nieYe-{s·,· 

s inc~ near 1 y - a 11 such large part ic i.es already would have been 

deposited in the upper respiratory tract and the 

tracheobronchial reaion. Deposition in the alveolar region 

during mouth breathing peaks at about 65 percent for particles 

with diameters of 3-4 micrometers and declines to around l? 

percent for particles with oiameters between 0.1-0.2 

micrometers. This peak is still present durina nose breathino, 

but it's level is much less (25 percent). Generally, this 

information shows that oarticles with diameters less than about 

10-15 micrometers generally penetrate deeper into the 

resoiratory system than larqer particles. 

2. Clearance of Particulate Matter From the Resoiratory 

Tract 

Clearance is the ?rocess whereby particles are removed 

from the respiratory tract. This process is described in this 

section in a simplified manner. It must be noted, however, 

that the mechanis-ms for removing particles are often complex 

and the efficiencies of these mechanisms often vary 
0. 1 

0 

O.l 

o-5 

Fi'gure 6-2 [6, 7] .. 

~sitial- iri the Trac..~ch.ial 

and Alveolar Re¢cns 

9y L'1dicated Particle Di..an'eter 

i I I j - I 

Range of alveolar deposition 

couth b:eathing. 

Estima:e of alveolar deposition 

nose breathing. 

I -

Range o! t:-acheobronchial deposition 

mouth brea:hing. [b]* 

E~t=~?~·iatio:\ of above to point 

p:edi~:ed by Re!erence 4. 

Ehtrwpola:ion to point 

deconstra:ed by Ref erenca 7 

O.~ O.J 0.-' O.S , .0 :.o J.O .: .0 5.0 

?!IY:i!C.:..L 01.:.1.l!:T~::\. ;:n1 AEliOO'i'tJ.:.l.llC 01.l.!.IET:R. j.1111 

I . \ 

J 

l 

I 

_, I 

' I \ I \ l 

\ =1 

, I \ 

, I . . ._ : .. -\ ·.· · .. '·· ""'•"··:'.':! - .. . ,, . ' ..- .............. , , ..... ,,,,, .. ,,,.-

·~ . ·~ 

J 

\0.0 

Ca 1 Deposition is expressed as fraction of particles of a given diameter 

entering the mouth (or nose). 

lbl Tracheebio1lchial deposition during nose breathing likely would be. less 

than that depicted for mouth breathing. 
:.•· ~· 

6-6 

smoking, pathological abnormalities, and response 

pollutants. A more complete description of 

clearance is available in Reference .2. 

to inhaled 

respiratory 

Particulates mav he removed from the respiratory tract in 

two orincioal ways. ~irst, oarticles which are soluble in body . fluids (or the soluble coating on insoluble particles} mav 

dissolve in any reoion of the respiratory system where. 

neoos it ion occurs. After di sso lu t ion, the constituents of the 

oarticle may interact locailv with cells or tissues, or they 

may be absorbed into the blood and transported to other areas 

9_f J:J:i~ .body. . _. _ .. 

Second, relatively inert ari.d insoluble particles may be 

removed from the respiratory tract by more mechanical means. 

~he orocess is somewhat soecific to the various regions of the 

system; therefore, each region is discussed separately. 

Clearance of insoluble particles from the anterior portion 

of the upper respiratory tract takes place mainly by blowing 

the nose or sneezing. In the posterior portion of thi~ region, 

the coriducting airways are li~e~ with ~oth ciliated cells that 

have hairlike projections and mucus-secreting cells. ~articles 

that are deposited in these conducting airways are trapped in 

the mucus and are mechanically transported by cilia action to 

the throat, where they are either swallowed, entering the 

oastrointestinal tract, or expectorate<1. This clearance 

mechanism is called the "mucociliarv convevor." Clearance in 

the upper respiratory tract is· normally rapid (i.e., 

minutes). [61 

.- .... 'J'h~ ·pr-ima.ry.·· clearar:ice -.,.mechani•sm ···in ---.t!"le - t·racheobroncia·i ···-

:.·- r·ecHon ·i·s ·a··lso· ·the muc<5c.iliarv con•ievor·. As described· above;·--~. 

entrai:'1ed particles are transpor.ted .:to the throat where they 

mav 1-ie swallowerl, thereby entering the c;rastrointestinal tract, 

or exoectorated. Smaller oarticles, 1.¥hich may deposit in the 

smaller airways deeper in the lunq ,. take longer to clear than 

lar9er particles, which tend to de?osit in t~e larqer airways. 

Generally, however, clearance from the . tracheobronchial region 

o: the respiratory system normallv takes hours to days. [61 

The principal clearance route in the alveolar reaion is 

via alveolar macrophages. These specialized cell·s phaoocytize 

(i.e., ·engulf) deposited particulate matter. Some macrophages 

containina oarticulate travel to the mucociliary conveyor of 

the tracheobronchial reaion where they are cleared through the 

aastro intestinal tr act. Others travel to 1 vmoh nodes and are 

cleared from the body throuah the lvmphatic system. C:learance 

of insoluble particles from the alveolar region generally takes 

months or years.(6J 
. : ~ .I'·: 

6-7 

3. Related Health Concerns 

There are two principal concerns associated with the 

deposition of inhalable particulate in the lower respiratory 

tract. First, ?articles deposited in this area, ~ven if not 

directly toxic themselves (e.g., inert particles)~ may have 

hazardous·····- rnat-ed:als adsorbed onto their surfaces. 

Conseouently, these adsorbed, hazardous materials may be 

transported deep into the most sensitive areas of the lung 

where they may cause localized effects or be absorbed and 

circulated to other parts of the body, causing problems 

·elsewhere. Second, all particles deposited in this area have 

relatively long residence times. As discussed previously, 

clearance of particles in the tracheobronchial region may take 

days, while in the alveolar reqion it may take years to clear 

insoluble particles. These lonq residence times provide a 

greater ooportunitv to oenerate health problems even if toxic 

materials are not present. Both of these concerns have led 

r.?A's Office of Air Quality Planninq and Standards to recommend 

that a NAAOS be established for particulate matter with 

diameters of 10 micrometers or less. (fil Therefore, the 

particles in the ambient air which are associated with the 

effects of concern have two aeneral characteristics: 1) 

chemical con st i tu en ts that are soluble in body flu ids, and 2) 

diameters of 10 micrometers or less. 

""hese general char·acter ist ics of typica 1 particulate 

matter that cause adverse non-cancer health effects are 

imoortant later in this analysis, since the greater the 

similarity between this particulate matter and diesel 

oarticulate, the stronqer the inference that diesel particles 

··-·can ...... a 1 so . g a.1,.i'se '. a<l.'.f e.r s·e· ~~·ne·a 1 t:h:.'.-~e;f.fe:.cts~~ ... ~he .key:,. po.in.ts ... ;-·~:<?·::~ . .•. -· .•. .. remernher" ;ire: . . . . . . - .. .. . . . . .. . . 

1. Deposition in the respiratory system is 

particle-size dependent, 

2. Smaller Particles with diameters less than about. 

10-15 micrometers are transoorted into the deepest oortions of 

the respiratory sys tern (tr acheobronch i al or a i veolar r eq ions) 

where they reside for lona periods of time (hours to years), and 

3 • 

particles 

diameter 

dependent 

Within this subset of inhalable particles, some 

are neposited in greater amounts dependina on their 

and the heiahts and breadths of these peaks are 

on the mode of breathing (mouth versus nose). 

8. Bffects of Particulate Deoosition in the Lower 

Resp1ratorv Tract 

As stated in t~e previous section, the deposition of 

inhalable particulate in the tracheobronchial and alveolar 

reqions of the respiratorv tract oose the qreatest threat to 
-· •,t ~ ~~ .... ---~~ .. 

6-8 

1. Reduced lung function, 

2. r...qaravation of · existina respiratorv 

(especially for bronchitics and asthmatics), - disease 

3. Increased infectious disease, and 

4. Predisposition to the development of bronchitis.[61 

In the alveolar region the effects of concern include: 

1.- -· Reduced lung function, 

Z. Damage to lung tissues, 

3. Increased susceptihility to infection, and 

4. Aqqravation or predisposition to cardiopulmonary 

diseases. [ 6] 

These effects have been observed to varyina degrees- in 

laboratory and ep idemiolog ica 1 studies. Because of individual 

variation and limitations in analytical :nethodologies, it is 

difficult to tell at what particulate concentrations these 

_effects begin or become significant. Presently, many of these 

effects.do not appear to have clear thresholds. [6] 

'l"he exact causes of many of the 

effects are not well known, but the 

res9onses are qenerally involven 

above non-cancer health 

followina mechanisms or 

either 'sin9ly or.-· in 

'-:".- .. ~..,..,-C:.-.,?~.~il')~~'t.!~~IJ-:J:~~-~J;:,.:._ .. ,,,. _ .. , .. c· c; .. · ••. ·--•. , ... ····.:-·. ---:::.:··:·.o--:-.-o_·--·.·---'-:-•-<7"•·.:·'-'·-·~:~::"··-:· -:-_:- -~~-.-.· --,., 

._. .·. - ~ ~ .-:- ...; '-::• <' ... • - - - ~ ·-··-- .. ~.: ._ •. :-:·. "•,;;0:: .: .. ;, 'r:.f. __ :.·_.;_- -.~- •'•-t. - . Z•:" :_. ..,; :· " ., ... .. .. ~.. ~ . ,., ; 

1-. ~acroohage damaae due to ohysical overloadin9- with 

particles or because of a toxic response to chemicals adsorbed 

on oarticles; 

2. Bxcess mucus secretion causing a reduction in the 

flow rate of the mucociliary conveyor; 

3. Structural changes in the lung tissue nue to 

physically or chemically induced damage; 

4. ~eposition of particles in excess of the lung's 

clearance ability with an attendant build-up of particles; and 

5. Bronchioconstriction of airwavs due to the 

stimulation of nerves in the tracheobronchial region. 

While the health effects listed ahove are a steo closer to 

overall human health than the lung functions (mechanisms) just 

descrihed, it is the list of mechanisms which will be most 

useful helow in assessing the relative potency of diesel 

T"),:u·1-;,..,,113tp 'l'hpl"'p ~,.P c::iTT1..-,1v '"'"'r P""nl'oh ,.:l=-~:l n ... ~hp pfFp,-.~ nF 
6-9 

diesel particulates on the tyoes of health effects listed 

above. w·hile the amount of available data on the effect of 

diesel particulate on lung function is also less than 

des i reabl~, it is area ter than that on heal th effects and wi 11 

provide the basis for comparison below. 

II!. ~on-Cancer ~ealth Effects of Diesel Particulate Matter 

A. tnhalation of Diesel Particulate 

Concerns reqarding the health effects of ambient exposures 

to diesel particulate were first based on its physical and 

chemi·cal characteristics~' The particulate-· matter from diesel 

engines is composed of basic units which are 0.1 micrometer or 

less in diameter.(81 These units form agglomerates with 

diameters ranaing up to a maximum of about 1 micrometer. Most 

of the agq lomer ates, however, are significantly srnal ler than l 

micrometer in diameter (90 percent by mass), with about 50 

percent hy mass being 0.3 ·micrometer or less. [8,9,10] The 

small size. of diesel particulate means that it is deoosited in 

the lower respiratory tract, where clearance may take years. 

Also important is the fact that the ~asic particulate unit 

is composed of a carbonaceous core with a wide variety of 

orqanic comoounds adsorbed onto its surface. While at least 

one study specifically identified 70 organic compounds 

associated with diesel particulate, [81 the qreat maiority of 

the individual compounds remains unknown. Such chemical 

constituents could react locally with the cells or· tissues of 

the lung, or be transported to other areas of the body • 

.. T~ese. a~e the san:i~ __ 9en~ral . .__c~.~E<?c:tesJe.ti.~~ ...... that w_~_;·e ..... ,. ··- __ .. : .. "fae-n·tT-fTe'<1·· above ·for -tyoic·a l i nhalab le particles. 'T'he re eor~e-r-:--·.:. -· .. ·=·~:-nba sed solely on the inhalation characteristics of diesel 

particulate, it is loqical to exoect that exposure to diesel 

particulate could cause the same adverse non-cancer health 

effects as other inhalable particul~te. 

B. Effect of Diesel Particulate Deoosition in the Lower 

Reso1ratorv Tract 

This inhalation-based connection between inhalable 

particulate and diesel particulate has f os t.ered research sneci~ically aimed at understanding the non-cancer health 

effects of exposure to diesel particles. The results of this 

research can be used to resolve two issues which are of 

paramount concern. First, does diesel particulate actually 

elicit the same adverse effects or responses that were 

described above for inhalable particulate in general, as would 

be expected based on the similarities between the particles? 

Seconn, is exposure to diesel particulate disproportionately 

more hazardous than would be suggested by its con tr ibut ion to 

the concentration of inhalable particulate suspended in the 
6-10 

ambient atmosphere because of its deep lunq deposition and 

adsorbed chemicals? More specifically, is the potency of 

diesel particulate and the mixture· of inhalable particulate in 

the ambient air significantly different, so that any increase 

in diesel particulate beyond current levels would be esoeciallv 

hazardous? These two quest ions are discussed separately 

because one issue can be re-solved more conclusively ·than ·the 

other at this time: the first question in this section and the 

second in th~ next. 

Two types of $tudies which specifically deal with diesel -,--'.-emis-s-t·o-ns··-~--a·re-·-·-most - -use·fu1 - - in - answetinq etth-er·-- c)f- these -- --·· 

questions: epidemio·1·ogica1--- and laboratory. Before the 

f indinqs of these studies are presented, it should be noted 

that most of this research has already been comoiled or 

reviewed in References 3, 11, and 12. Because of this, only a 

brief overview of the literature will be presented here. 

The epidemioloqical research into the non-cancer health 

effects of diesel particulate exposure is extremely limited • . There are no studies which. specifically evaluate. diesel 

particulate. Only a verv few studies evaluate diesel exhaust, 

and diesel particulate by association. The primary reason for 

this is the lack of suitable populations available for study. (l] 

. S-ome of _the __ sfi1dies_ that l'!ave been completed su~gest that 

occupational exposure to diesel exhaust (e.g. , railroad, 

transit, mining workers) results in a higher prevalence of 

chronic respiratory symptoms, bronchitis, and loss of lunq 

function. [ 3 J Other studies have shown no significant adverse 

-- -- - -.: ~-~··t{~'."t't;f~u·a1s~1~)-~~;Q, ·"--'T~~~~:-~:~~t-e~;~~c;!."'r;{ff~f~~~-~-~- it~~-l _:::~-~-~~:i~I~"~~-~~~~:'.:~:~::~ ·---·---·---· --- . eo-fcfe-mioloqical studies SUOgeSt that Chronic eX?OSUre to d1esel 

exhaust, including diesel particulate, may adversely affect 

health, the results are inconclusive. Because of this, no firm 

conclusion reqarding the health effects of diesel particulate 

can be made based on this type of information. Thus, the 

results of laboratory studies must be examined to better 

determine the effects of diesel particulate exoosure. 

Most laboratory investigations of di es el part icu late 

exposure have been conducted at hiaher_ particulate 

concentrations than normally would be encountered in the 

natural environment. This is common practice in such studies 

and is done to reduce the cost of such research. Because of 

the hiah exposures used in these studies, they are very useful 

in identifying the mechanisms or responses that would account 

for the effects of concern that are observed in the "r·eal 

world" (e.g., bronchitis and infectious disease). However, 

they are less use fu 1 for id en ti fyinq heal th effects that wi 11 

occur at realistic exposure levels. 
6-11 

Most of the laboratory stu~ies involvino diesel 

particulate have shown, to varying degrees, the same basic 

effects on lung function that were oreviously described for 

inhalahle particulate matter, including alveolar macrophaqe 

damage, excess secr~tion of mucus, lung tissue damage, possible 

adverse effects on the immune system, and particle build-up in 

the luno. [3,11,121 This similarity of response provides· st'tOng· 

evidence that exposure to niesel particulate has the potential 

to elicit many of the - same adverse health effects which were 

also previously described · for inhalable particulate in 

general. Therefore, the original concerns regarding diesel · particula-te that were based simply on its inhalation 

characteristics are supported by more recent direct evidence. 

C. The Hazard of Diesel Particulate Relative to General 

Inhalable Particulate 

'rhe issue of ~iesel particulate's relative hazard is a 

more difficult issue to resolve. As discussed above, the few 

quantitative eoidemiological studies are not useful to 

characterize the non-cancer health effects . of diesel ~articulates because their results are inconclusive. ~lso, the 

use of verv high particulate concentrations in the laboratory 

studies generallv precludes using this research to evaluate the 

health risk of ambient exposures to diesel particles in 

comparison to that associated with the ambient mixture of 

?articles. Nevertheless, some studies have investigated the 

systemic toxicology of diesel exhaust. Such studies are 

?articularly useful in evaluating the concern that the organic c~emicals adsorbed on. the surface of diesel particulate may 

make it nisproportionately more hazardous than other -·· · · , ... oa r·t-i.cu1a t·e-· in·'"the .' ambient mixt'u're •· .. ·· ··;.. · _,:·: . .- ··· · · · - .. ' . .., ··· ""'"'·'" ...... ,,., .. ·· · • • ~ " .. .... • r • • , 

Generally, the results of these studies have not 

demonstrated any s ion if icant gross tox icoloo ica 1 effects from 

exposure to d iese 1 particulate. ( 8] A possible explanation for 

this lack of effect is that other research has suggested that 

although the organic layer of diesel particulate is soluble in. 

body fluids, it may be released very slowly and that enzyme 

systems in the lungs may metabolize these chemical 

consitituents into more innocuous substances. [l] Therefore, 

this information suggests that the organic layer of diesel 

particulate may not cause significant non-carcinogenic 

toxicological effects. Until more information is generated, 

however, the possihility that diesel particulate may be 

disproportionately more hazardous cannot be dismissed. 

Information concerninq the efficiency with which particles 

of various sizes are deposited in the lower respiratory tract 

may also provide some insiaht into the relative hazard of 

diesel particulate. It was previously stated that almost all 

diesel particulate is smaller than 1 micrometer in diameter. 
6-12 

Figure 6-2 shows, for example, that the deposition for these 

sized particles in the alveolar region during mouth breathing 

is substantially less than for particles with diameters of 1-6 

micrometers. (The effect is present, though less dramatic, for 

nose breathing.) Therefore, particles in the ambient air which 

are somewhat larger than diesel particulate may pose a slightly 

greater health hazard on the basis of mass deposited in the 

lower respiratory tract. This suggests that, on a mass 

concentration basis alone, diesel particulate may not be more 

hazardous than would be accounted for by its contribution to 

the total ambient mixture of inhalable particulates, and that 

it could be slightly less hazardou.s. than certain larger, though 

still inhalable, particulate. Here again, however, the 

information is simply too limited to make any conclusive 

judgments. 

IV. Summary and Conclusions 

Based on the available health effects and deposition 

studies, there is no direct evidence that diesel particulate is 

disproportionately more potent in causing non-cancer . health 

effects than an equivalent mass of the current ambient mixture 

of particles. However, this information is so limited that it 

does not provide a sufficient basis for conclusively 

eliminating the concern that diesel particulate may be more 

hazardous because of its chemical composition and deep lung deposition. Therefore, the issue of diesel particulate's 

relative hazard cannot be fully resolved at this time. Ongoing 

research may shed more light on this issue in the future. 

The following overall conclusions regarding the non-cancer · -·.··heal t·h · e·f fee ts o.f · die s-e 1---par t-icu late· :a r·e ·possible,. ba·sed ·on · t.h.e ,. ·±·nforma'tion--summarized above." ···· ··· -

1. Laboratory studies have shown diesel particulate 

matter has the potential to cause or contribute to adverse 

health effects such as reduced lung function, damage to lung 

tissues, increased suceptibility to infection, aggravation of 

existing respiratory disease, predisposition to bronchitis, and 

aggravation of or predisposition to cardiopulmonary disease. 

2. There is insufficient evidence to conclusively judge 

whether diesel particulate is or is not more hazardous than the 

mixture of various particles suspended in the ambient air with 

diameters of 10 micrometers or less (i.e., inhalable 

particulate). The very limited information from health effects 

and deposition studies suggests that diesel particulate may not 

be more hazardous under certain conditions (i.e., mouth 

breathing). However, until more data becomes available, diesel 

particulate should be considered as harmful in causing 

non-cancer health effects as the ambient mixture of inhalable 

pa rt icles. 
6-13 

References 

1. "Inhalation Toxicology of Diesel Exhaust ?articles," 

In: Diesel Emissions Svmposium Proceedings, McClellan, 'R.., A. 

Brooks, R. Cuddihy, 'R.. Jones, J. r-Aauderly, and R •. Wolff rJ.S. 

FPA, ORD, 1981. 

2. "A Subchronic Study of the Effects of Exnosure of 

Three Species of Rodents to Diese~ Exhaust~" In; Diesel 

Emissions Symposium Proceedings, Kaplan, ~. L., w. F. 

~ackenzie, ;:;. J. ~prinqer, R. M. Schreck, and J. J. Vostal, 

U.S. -~PA, ORD, 1981. 

"3. "Impacts of niesel-?owered Liqht-Duty 

Health Fffects of Exposure to Diesel Exhaust," 

Research Council, 1981. 

Vehicles: 

National 

4. "Size Considerations for Establishing a Standard for 

Inhalahle Particles," Journal of the Air Pollution Control 

.h.ssociatio·n, Miller, i:-., s. Gradner,T c;raham, R. T...ee, .Jr., t-1. 

w1ls.on, .and .r. Bachman, 1979, Vol. 46, pp. 610-615. 

5. "Air 0uality Criteria for ?articulate Matter ana 

Sulfur Oxides (Draft)," U.S. EPA, OAQPS, December 1981. 

6. "Review of the ~ational Ambient :r..ir (")uality 

Standards for Particulate Matter: Assessment of Scientific and ~echnical Information," U.S. SPA, OAOPS, January 1982. 

7." American Industrial qygiene Association," In: 

Diesel Emissions Symposium Proceedings, r:han, T. and ~. 

--- :LTppman, v~ol; ... "4'1/-p~ ... ·. 3'9·9·~·4'0'9~, ·19~0': ·":'.""·';":'_·:-~--' ... \:·: . ·· · ·.... ,. .. _ · •····~_" ....... r•• 

8. "EPA Studies on the Toxicological Sffects of Inhaled ~iesel Engine Emissions," In: Diesel Emissions Symposium 

Proceedings, ?epelko, w., U.S. BPA,_ORD, 1981. 

9. "Characterization of Particulate and Gaseous 

Emissions from Two Diesel Automobiles as Functions of Fuel and 

Driving Cycle," Hare, ~. and T. Baines, SAE Paoer No. 790424. 

10. "Characteristics and Oxidation of Diesel 

Particulate," In: Diesel Emissions Symposiu~ ?roceedings, Trays~r, ~.h.., L. J. Rillenbrand, D.S. SPA, 0RD, 1981. 

11. Diesel Emissions Symposium Proceedings, U.S. EPA, 

ORD, 1981. 

12. "Health 

Proceedings of an 

Edited by Peoelko, 

December 1979. 

Effects of 

!nterational 

r.v • , R • D a n n e r , 

Diesel Enqine Emissions: 

Symposium," Vol. l and 2, 

and N. ~lark, U.S. SPA, ORD, 

:.--· 
CHAPTER 7 

SOILING EFFECTS 

I. Introduction 

With the increased use of diesel-cowered vehicles, the 

impact of diesel oarticulate emissions on material$ has become 

a subiect for investiqation. 'L'he major material effect 

associated with chemically non-reactive atmospheric particles, 

such as diesel particulate, is that of material soilina. [41 

This chapter will examine the effects of diesel oarticulate on 

soilinq. · 

·In t·he past, .the vast majority of soiling studies· have· 

dealt with aeneral atmospheric particulate, while little work 

has heen done soec if ica 11 y on the soi 1 ina impact of d iese 1 

particulate. However, by considerina the relative 

characteristics of diesel particulate, it is possible to adaot 

the findings of studies addressing atmospheric particulate 

soilina to diesel particulate soilin9. 

'T'he soiling effect caused t'ly increased ambient levels of 

aiesel particulate can he addressed in a number of ways. One 

approach would be to derive three relationships: l) a 

relationship between ·ambient particulate levels and the 

physical phenomena of soilina (i.e., particle deposition), 2) a 

relationship between soilina and cleanin9 frequency, and 3) a 

relationship between cleanina frequency ann cleanina costs. By 

combinina the three, a relationshio hetween ambient particulate 

levels ann the cost associated with removinq the soiling can be 

obtained. ~owever, with this aoproach intermeaiate 

relationships are also determinable (i.e., the relationshio 

between ·aarticulate levels and cleanina :recruencv). .A. second. - aooroach~ would be to· derive a sinole relationshio betwee·n-.u·.·"'":.~ ... • ~ ·•.• ••• r ....... 'It•" ..... - • r• .. ;1"o1 l" ' .• "' ~ • • • ' . •• ' ·r· . ,._, •• ,.. - ... • .... • .• ... .... 't'·· "' •· :1 • • • 

· · amhient particulate levels and the cost· of soi11na. · "!'his 

latter methodology usuallv utilizes survevs of individuals' 

intentions or actions to determine a "willinaness-to-oav" 

associated with a decrease in soilinq. Derivina a relationshio 

hetween ambient particulate levels· and the behavior of the 

oeoole affected bv soilinq is still another aoproach~ thi~ 

approach may utilize prooertv values in its methodoloay to 

determine the cost associated with a reaction to soiling. 

Th is anal vs is will not address any economic costs 

associated with soiling due to the controversy connected with 

the existinq economic soilina analyses. Instead, this analysis 

will only address the practical aspects of soiling (i.e., 

soilina as a function of particulate concentration and cleanina 

(or other soiling remedy) ·frequency as a function of soiling). · 
7-2 

This restriction in scope has the unfortunate side effect 

of olacinq the great majority of the research addressing 

atmospheric particulate soilin~ outside the scope of this 

studv. '!'he remaining research or ima r i ly addresses the effect 

of total susoended oarticulate ("!'S'P) on soiling, with little 

havinq been done on the eff.ect of soilinq on cleaninq freauencv 

or on the soilino. effects of various subclasses of 'T'SP·. 1'\Io 

experimental research has been conducted on soil inq by diesel 

particulate. 

raven this, this study will take a three-step approach to 

address the issue of diesel particulate soiling. First, the 

- physical pr-ocess of soilinq will be defined and descrihed. 

Second, studies addressing soiling by TSP will be reviewed to 

assess the current state of knowledge in the area. 'i'hird, 

soilinq by diesel oarticulate will be compared to that by TSP 

by comoarino the ohysical and chemical properties of both types 

of particulate and oostulating their effect on soilinq. The 

goal of the entire process will be to arrive at some· relative 

value for the soiling effect of ambient diesel particulate to 

that of TSP. 

!!. Descriotion of the Soiling Process 

Soilino is defined as the build-uo o: a layer of deposited 

atmospheric particulates on an exposed surface.[11 A soiled 

surface aopears dirty to the eye and, as the layer of deposited 

particulates increases·,- 1t will become detectable by· touch. 

Characteristics associated with soilino are: 1) a loss of 

reflectance of visual liqht by an o-paque material surface, or 

2) a reduction in liaht transmission throuah a transparent 

material. 

- -·~ ........ - -T"~e ·t-ime_c __ frit.er;v~f-·· reot.d.r'ecf- to . tran.sform' her iz'o'~tal'- .a~n-cf" -·-

vertical surfaces from a clean to a perceptibly cirtv state is 

aenerallv determined bv oarticle com-position and the rate of 

deoos it ion. This or oces s is also influenced by the location 

and soatial alianment of the material, the texture and color of 

the surface relative to the particle, and meteoroloqical 

variables like moisture, temperature and wind soeed. [21 

'i'he degree of soilinq is determined by measuring 

reflectance frorn an ooaaue surface and by measurinq haze 

through a transparent surface (window qlass is the most common 

transparent surf ace) • "T'he area ter the or io in al reflectance of 

the surface, the more observable the soilino will be. [3] 'i'his 

can easily be seen hy imaqininq the effects of soilinq on a 

white~painted surface, which has a reflectance of more than 90 

oercent, as comoared to the effects of soilina on a 

black-oainted surface, with a much lower reflectance. Of 
7-3 

course the soiling effects on a dark surface by a white or 

lioht-colored particle is equally observable, but because 

diesel.particulate is dark, this is not a concern. 

I!T. Atmosoheric Particulate Soilina 

A small number ·of studies have been performed relating TSP 

levels to the ·physical r·ate of soiling. This section will 

!;riefly review four such studies. The first two studies were 

experimental in nature and simply attemoted to determine the 

relationship between particulate concentration, time, and 

soi 1 ing. 'T'he th i rq s tudv used surveys and at tempted to go one -· · --steo· further-· by· relating pa·r·t-i"cle concentration to the 

"•::: ·\ 

frequency of soiled removal (in this· case, paintino). The 

fourth studv, a literature review, identified those cleanino 

tasks that would he affected by increased soiling resulting 

from increased ambient particulate levels. 

In the first study, Parker attempted to determine the 

relationship hetween chanqes in the reflectance of a surface 

and the accumulation of particles. [ l] Reflectance chanaes of 

white painted surfaces showed a first order dependence upon 

total pollutant dosage as defined by the exoression: 

R = Rp + (R0 - R0 ) exp (-KCt) 

Where: 

R 

Ro 

Ro 

K" 

r '.- ": .... ~. ·: 

t 

= reflectance of the surface, 

= initial reflectance of the surface, 

= reflectance of particles, 

= deoosition rate constant, 

=" particl.e .. <:oncecntrtft.i§fi, .,., ...... . ~·exposure tini"e·: -· .. . . . . .. ~.-: .•;. 1 - , ~. , I 

Tt is interesting to note that, if soiling is defined as 

the chance in surface reflectance CR 0 - R) rather than simply 

the surface reflectance (R), the above equation becomes: 

Ro - R = (Ro - Rp) (1 - exp (-r.r.t)) 

'T'h is is the equation for exponent ia 1 !Jecay, which, among 

other processes, describes the decay of radioactive .materials. 

~he chanae in reflectance is rapid at first and· slows as time 

qoes ·on. 'J'he final reflectance of the surface approaches the 

reflectance of the ~articulate assvmptotically (i.e., very 

aradually). A douhlinq of the particle concentration would not 

affect the final reflectance of tlte surface, !Jut woulc; double 

the rate of soilino. ~his is shown in Figure 7-1. 
7-4 

In a ·second, similar studv, Beloin and Havnie exoosed six 

materials to particulate soiling. [4] .'A. linear r-eqression 

analysis resulted in the followina relationshios for two of the 

materials: 

1. ~or acrylic caint: 

Ro - R = 92.5 - R = l.36C•34St.612 

2. ~or white asphalt shingles: 

where the units of C and t are microqrams per cubic meter and 

months, res?ectively. 

Here, soiling (R - R0 ) is deoendent on certain oowers of 

both cart icle concentration ·and time. While these 

relationships appear quite different from that put forth by 

Harker, they are not entirely inconsistent. First, Beloin and 

Haynie were actually addressing a_ situation quite different 

from that addressed by Harker. Beloin and Haynie's experiments 

and their correlations included a variety of particulate types, 

a].l havina different properties. f-1'ar-l<en's relation only 

aoplies to a single type of particulate. Seconn, the powers 

associated with particle concentration anCi time in the Beloin 

-and Havnie eouations are all essentially between zero and one~ 

which is what would be expected if the orocess described bv 

Farker was examined for a specific period of time. The fact 

that the oowers for concentration and ti1T1e are not eoual is 

more of a question, as Farker's model imolies they should be ·- ";:;;: .. ;:;:;.-,.., -~ .. --::;_fi:;:_t;h'e--:;:-~s .. ame··; -? -,~H·oweve-·r,~ ,;.; ,,the-~ f a-c-t·-: that·--' 8e·lf-o,i·:1--":-a·na::0 --Ha vni·e-.. ·-1nc-B1:Jde·d'-""-·:;· --- ·: -· -~ ~--_-:·~ d ~--ff ere nt _-, t.·v?e s _;._-of.:: p~fft-i'cu·ra_-te -~ in-~··_th·e·ir;"··-stu~y· ~=could - ·be ·: the.,:_ -

exolanation. 

~o illustrate this possibility, a portion of the data from 

the Reloin and Faynie study and -their equation for acrylic 

paint have been reproduced in Fi9ure 2. A specific instance of 

Farker' s equation was then fit to the -data. As can be seen, 

the two relations aaree verv well and both describe the data 

adequately. Thus, while the exact form of -the relationship 

between soilinq and carticle concentration is not known, it is 

clear that atmospheric particulate noes result i·n soi 1 ing and 

that an increase in particle concentration wi 11 increase the 

degree of soiling, and very likely to the same degree (i.e., a 

doubling of particulate will douhle the soiling). 

A relationship between the frequency of house repainting 

and atmosoheric particulate concentration was shown in the 

third study by Michelson and Tour in. fSl A mailed survey of 
7-5 

households in the uooer Ohio River Valley established a linear 

relationship betwee~-repainting frequency and ambient levels of ~articulate matter. i:.towever, additional data are required to 

establish a more definite correlation. Maintenance data for 

additional cities should be added to the study to increase the 

study size: other factors to be considered include the effects 

of other oollutants that may .. be present and also the 

socioeconomic effects of the households in the survey. 

In the fourth and final studv, Watson and Jaksch[61 

examined the soiling literature to- determine which common 

household maintenance and cleaninq tasks would be affected bv 

atmospheric particulate soilinq. - i:'he Watso·n and Jaksch stud·y - selected eioht tasks as those most likely to be noticeably 

soiled by particulates: those tasks for which there was little 

or no evidence of heing siqnificantly affected by soilinq were 

eliminated from consideration. The eioht cleaning and 

maintenance tasks that would be affected by atmospheric 

particulate soiling are: 

Indoor Outdoor 

Painting walls and ceilings Painting walls 

Wallpapering Paintino trim 

Wash i_ng walls Washing windows 

Washing windows 

\.leaninq venetian blinds 

... 

No a_ t temot - was· made, however, to determine the dear ee of the 

effect that soiling had on the frequency of the ?erformance of 

these tasks; only that the effect would be sianificant. 

A.aain, as was the case with the first two studies, the 

·usefulness of the latter two studies is limited. "Jo 

quantitative relationship between atmosoheric particle 

concentration and cleaninq frequency can be drawn. i:.towever, 

the evidence indicates that not only does susoended particulate 

cause soiling, but soiling affects the performance of cleanina 

and maintenance tasks. Thus, increased ambient ?articulate 

levels will lead to increased soiling, which will have a cost 

associated with its removal. 
7-6 

IV. Diesel Particulate Soilina 

The previous descriptions of atmospheric oarticulate 

soiling refer to TSP (i.e., less than approximately 3n 

micrometers in diameter). Diesel particulate falls into a 

subclass of TSP (fine particulate, that are less than 

accroxirnatelv 2.5 micrometers in diameter) and both its 

physical and. chemical characteristics could quite likely cause 

it to have soiling .. -properties different than those of TSP. 

Unfortunately, there exist very little direct experimental data 

demonstratina the relative soilina effect of fine oarticles or 

d iese-1- par ticula-te to those of TS?. Because of "th is, it is· 

necessary to compare the characteristics of diesel particulate 

and TSP and postulate the effect of the differences on their 

overall soilinq impact. 

The physical and chemical properties of particulate which 

most affect the dearee of soiling damage appear to be 

reflectance, stickine~s, and size. Wallin has measured the 

optical reflectance of diesel particulate and found it to be 

generally about 3.5 times blacker than average urban 

particulate. [7] Thus, the change in reflectance due to 

deposition of diesel particulate will be areater than that of 

TSP because the difference between the reflectances of the 

surface (R0 ) and the particulate (R0 ) will be greater. 

This is caused by the high carbon· content of diesel 

oart-iculate,- which has a reflectance of almost zero. Diesel 

oarticulate also appears to stick to surfaces more than the 

averaoe particulate due to its oily nature (i.e., heavy 

hydrocarbons bound to the surface). (81 

· ·. - ..:._.. · ~- ~- _. .·. - ::;_.: • ..,;_·-'_ :~,i·n'.- ~ g .: . ·r: ~1:>b;t"t':··:::··pr e..,.par ea-··· ·for;·: "'t.'l'Ye" ,..._caJ if or; n·ta _::Air_·· ~e sq a:(·c;.e·~· 

,._,. '"' ·.~.' "··";•"::.i:fo·atd'·;· ~sa'wver''" and·- Pitz· ·ae.-t ined . a "s.o l'i' ing_, i~'a'e .. x"" -"'as~ the --·?aYio· 

of the diesel particulate soiling to averaae urban particulate soilino on the basis of equal ambient mass concentrations.[8] 

They then went on t~ estimate the value of this index based on 

the relative pro~erties of diesel particulate and TSP. 

The effect of different optical properties was taken from 

Wallin's study and translated into an initial soilino index of 

3 or 4 based on this sinqle parameter. Because no experimental 

data are available on the stickiness of diesel oarticulate in 

quantitative terms, Sawyer and Pitz estimated a combined 

soiling index of 5 based on the combined effects of both 

reflectance and stickiness. To bracket the uncertainty, a 

ranoe from 2.5 to 7.5 for diesel soilinq indices was 

considered. (~o effect due to different particle size was 

included. ~hile it apoears in some cases that small particles 

may deposit in greater amounts due to their greater diffusion 

capabilities, in other cases larqer particles would deposit 

faster due to their greater mass. Thus, no clear preference 

based on size can be determined.) 
7-7 

As an example of how this soiling index would be used, one 

can assume an area with 75 ua/m3 of TSP present. ~his 

concentration would have what could be called a soilinq 

potential of 75 ua/m3, since TSP is the base particulate 

(i.e. , a one- to-on-e correspondence between mass concentration 

and soilina potential). If S ug/m3 of diesel · oarticulate 

we re added ·to th is atmosphere, the concentration of- TSP would 

become 80 ug/m3, an increase of 6. 7 Percent. Bowever, us ina 

a soiling index of .s· for diesel particulate, t~e soilinq 

potential with the addition of diesel particulate would be 100 

ua/m3 (75 + 5*5), an increase of 33 percent. 't'hus, one can 

see ,how adding a_. ·gi~e.n. conG~ntra tion of diesel particulate to 

the atmosphere can have a much greater effect on soilina than 

would be indicated by its effect on particulate mass 

concentration. 

v. Summary 

Very little data are available on the effect of ambient 

particulate on the absolute degree of soilinq and the frequency 

of cleanina. i:.towever, it -~s clear that ambient oarticulate, 

includinq diesel particulate, does result in soiling and has a 

cost associated with its removal. !n addition, it aooears that 

the deqree of soiling associated with ~iesel particulate is 

areater than that of TSP on a mass concentration basis: 

possibly between 2.5 and 7.5 times as great. Thus, when 

relatinq the soilina effects of soecific amhient concentrations 

of diesel particulate to those of TSP, the concentrations of 

diesel oarticulate should be increased by a factor 

substantially greater than l to place them in the proper ~ersnective with the TSP concentrations. 
7-8 

References 

1. "Particulate Matter Soiling of Materials," Harker, 

Final Report Draft for U.5. ~PA, EPA Contract No. ~8-02-3422. 

2. "Review . of the National Ambient Air Quality 

Standards for Particulate ~atter: Assessment of Scientific and 

Technical Information," rJ.5. EPA,, .OAOE.S, __ ,Tanu.arY-- 198'2. 

3. "Effects of Small Particles on Materials," Haynie, 

rr.s. ,EPA, Environmental _Sciences Research-Laboratory. 

4. "Soilinq of Building Materials," Journal of the Air 

~ollution Control Association, Seloin and Haynie, 197S:-

5. "Report on Studv of Validity of Extension of 

Economic Effects of Air Pollution Damage from Upper Ohio River 

Valley to Washinoton, l).C.," !'-1ichelson and 'T'ourin, Area 

Environmental Health and Safety Research Association, August 

1967. 

~. "Air Pollution: ~ousehold Soilinq and Consumer 

Welfare Losses," Journal of Environmental Economics and 

Manaqement, Watson and Jaksch,--i.9s • 

7. "Calibration of the D.S.!.R. Standard Smoke 

for Diesel Smoke," International Journal of Air and 

?ollution, Wallin, Vol. 9, 1965. 

Filter 

Water 

8. "Assessment of the Imoact of Lioht-Dutv Diesel ,._ ............. --~'"' ... -.v.e.tdc-le ?- .on Soi 1 inq -·.·i n.c-:GaLi.fo r·n.ia··;'" ~ S·aw.ye·r ~ and-: -P i"t-z , .. - p·r epa red···"' .. ~ · _-;-,-'.~ · •.:.-,1f·o:-r:; ;~t'h-~ ·~·-ra:"Ji!i;: cYr'n·i·a ··-~ti~'{'.· 'Re so'h ... r't:e-s·"-BOaf cif ~J a:n~1.ra·r"·./ --r9 s J: ; --- ·.-;: · ~ ,~-'! .... ~ :;>-
CHAPTER 8 

r. Introduction 

~. 0raani7ation of rhaoter 

'T'h is r:haoter arlrresse~ the economic irroact of the hase 

scenario relative to the rel"axed scen·ario. ll='ull descriotions 

of each scenario are aiven in the Tl"troduction\ The two basic 

trao-oxidizer nesians and the associated reaeneration svstems 

are descrihed in the re~ainner of this introduction. 

· · 'T'he next two ser.t-ions of- th-is chapter examine the economir: 

imoact of oarticulate c-ntrol' on J iaht-dutv diesel vehicles 

(L!inVs) and truc'<s <Loorrs), and on heavy-duty diesel enaines 

(UQDF.s). 'T'he suh.!'\ections in each section deal, in order, with 

estimatina the cost of the hardware reauirements for 

oarticulate control, e:.raminina t~e economic imoact on af~ecteil 

vehicle and Pnaine iTlanufacturers, estimatina the overall cost 

to t~e consumer of o~rticulate control, and estimatina the 

annual costs (for the vears 1987 throuoh lq95) and the 5-vear 

aaareoate costs (19P7 throuah lQ~l inclusive) of these controls. 

B. Oescriotion of ~rao nesian~ 

'T'he or il'1a rv r.o!l'oon en t of a nv svs tern ~or the reduct ion of 

diesel oarticulate emissions is the trap-oxidizer. In addition 

to· the tr a o i ts e 1 f , other ha r r1 w a re r. om oo n en ts are r eq u i red , 

with the soec if ic r eau i r emen ts depend i na on the has ic 

trao-oxidi7er desian used. 'T'rao-oxidizers ltraos) can he 

~roadlv .,i.vired into cateoories on the r-asis of two factors: 

location or clacP~ent: anil filter ~at~rial. 

. ... ' ' ... '~· - . 

: AM un~erfloor-mounted frao occuo·i~s-~oor~iimit~lv~~he same 

oosition, relative to the diesei enaine, as is occuoie<i hv a 

catalytic converter on a aasoline-fueled vehicle. A 

close-couoleo ~rao i~ located nearer to the enaine, ?~d is 

usuallv in~oroorated in the exhaust manifold ~esian. 'T'raos are 

a1 so cata1.vzed or non-catalvzeo, c:1ccorcHna to the presence or 

ahsence of catalvtic materiaJ.s to aid in tl'ie oxidation o~ 

accumulated oarticulate. 

Detailed descriotions of the ~esian and ooeration of each 

tvoe of trao can be found in the EP~ Trap-Oxir.izer ~P.asibilitv 

St:uav. r11 F'C"r tlii~ P.conomic analvsis, the costs and economic 

imoac t a re ha sed on 1 y on the undP. r floor-mounted A es ian, since 

it aooears to he t~P. oreferren ~esian of manv trao-oxidizer ann 

diesel vehicle/enaine manufacturers. Tl'ie oossibilitv of 
8-2 

c lose - co u o 1 e ci t r a o s he i n a u s e d i s a cM r P. s s e ri i n r ha o t e r J I) • "-To 

clear oreference for one of the two ~aior filtP.r materials has 

vet emeroed: a hrier ciescriotion of each follows. 

11.lthouah manv ·filter materials have been investiaated for 

uc:;e in traos, the currel"t focus or cieveloomer.t: and· test ir.a is 

on ceramics and alumina-coated wire mesh. reramic traos 

utili?.:e a non-cataJ.vtic, oorous ccirdierite material f2("4o0) + 

-2Jl'..l.2S\1J __ :±-_ c;_(Si07)l for the substrate. 'l'hi_s substra.te _i.!? ____ _ similar in construction to the suooort structure used for 

catalvtic converters in oasoline-fueled aoolications, tvoicallv __ c_o_ns i.st ina of a honevcomb nes ion with oar al le l saua re channels 

runnino the lenoth of the unit. 'T'his trao desion -is- beinq 

manufactured bv rornina, hlr.K, and other firms. 

Johnson-Matthey is the ?rimarv manufacturer of traos usina 

alumina-coated wire m~sh as the fi 1 ter material. 'T'he form of 

the wire mesh trap is a lonq cylinder with a hollow central 

core. 'T'h~ exhaust flows radiallv throuoh the ~esh filter from 

the outside toward the hollow core. Catalytic coatino of the 

wire mesh, lower ino the t~lfloerature necessary for trac 

reaeheration (oxidation of the accumulated particulate 

colJected hv the filter), is inherent in the ~'ohnson-Matthey 

des ion. 

Both tvoes of trao are enclosed 

shell, hasicallv t?ie same as that used 

of a catalytic converter. 

hv 

for· 

a stainless 

the exterior 

~. ~escriotion of Peoer.eration ~vstems 

steel 

shell 

~ .. -, ..... °'·:-.-.. c.--.:-.; T.ri .-aci~·itto-n., .-.'=ac-h-"""'.tv.oe ___ of _tr-.ao_ reauir,.~?.:., .?--.rnethon .9~---'-

., ~ ·- ·• - -: _.;,,-:. -'· ~r:-e·a-en e:ra ti on•" , ~ i n·c:-:-Ef ·:: exce-s·s ::: ·a·c·c·u1T1ula:t en• ... voa r·ti.c u-1-a:t·e ... ·t nc:: re as es .. ,·,, 

exhauc:;t h.-:icl<oressure (therehv decreasinc fuel ecol"'omv · ann 

vehicle oerformance), it must be oxioizen or burned off 

oerio~icallv. 'T'he temoerature of the niesel ex~aust stream is 

tvoicallv inadeouate to initiatP. or sustain this oxidation. 

~h~refore, a reaeneration svstem is also reauired for effective 

Particulate control. 

~he haraware components reauired ror an e~fective 

reaeneration svstem depend, in oart, on whether the trao is 

catalvzeci or non-catalvzed. ~he oresence of catalvtic material 

in the trao filter reduces the terrioerature increase needed for 

particulate oxidation, allowin~ the use o~ a less complex 

reoeneration system than is required for non-catalyzed trao!;. 

F.ach or th~se is brieflv described below: detailed exol~nations 

of the structure and functionina of trap reaP.neration svstems 

are availahle elsewhere. r1,21 
8-1 

'A. tvpical reaeneration svstem for a non-catalvzed trap is 

o as e d on ·a d i es e 1 f u e 1 burn e r , w h i ch in j e ct s d i es e 1 f u e 1 into 

the exhaust stream ;u~t before this stream enters the trao. 

Rurnina the ad~ed fuel increases the exhaust temoerature enouah 

to ianite the accumulated oarticulate. The enaine exhaust flow 

is temporarilv routed around the trao, while the hurner and 

trao are supolied with a controlled air flow· to ensure 

continued oxidation of the trapoed oarticulate without· 

excessive heatinn. 

'T'his tvoical reaeneration svst~m has seveii orimarv 

hardware components: a hurner head, a fuel delivery svstem, an 

ianition svstel'T', ari auxiliarv comhustion air svstem, an e~haust 

diversion svste~, ~vstem control sensors, and an electronic 

control unit r~cu). 

""he ~urrier head orovices a location for mountina the Fuel 

sorav nozzle, ignition olua, and auxiliary air nozzle. It is 

also assumed to include- a aas distribution haffle for evenlv 

distributina the comhustion oror1ucts over the cross-section of 

the trap. 

'T'he fuel nf'!liverv svste'TI orovido:s tl'ie diesel 

necessarv for initiating the trao reaP.neration orocess. 

svstem includes a fuel sorav nozzle, a :·~el Feed line, 

fuel solenoid valve. 

fuel 

'T'h is 

and a 

'T'he fue 1 i an it ion svs tern mav be one of two has ic tvpes. 

One svstem consists of a lona-life soark olua, a steo-up 

voltaae transformer, ari~ sianal con~itionina electronics for 

aeneratina a 'iiah-voltage discharae. 'A.n alternative to this 

svstel'T' is· a alow plug, like those used to cold-start cHesel 

.. ena i-nes'. ·· -,. . . --· ~·· ... ~ 

• ~ '".!~..: ... ~·· ... : J' ..... '!' . . :.-: t. 

... ... . .. ,·" ... ~ ... ,• .i'. 

""he aux i i'ia r-y air combustion svstem, which orov ides a 

controllPd air suoolv to the burner and trao to sustain the 

oxi<1ation of the accumulated particulat.e, consists of an air 

oump, a check-valve, a diverter .valve, and an air deliverv 

line. 'T'he check-valve prevents ~xhaust back flow in to the air 

oump, while the cHverter valve orovi.des an alternate path in 

the event that comhustion air ~ust he diverted from the 

Filter. 'T'he air deliverv line connects the air pump to the 

hurner head. 

'T'hp exhaust. niversion svstem temoorarilv r~routes the 

enaine exhaust stream arount1 the trao durina the reaeneration 

orocess. 1t corisists of a vacuum motor driven hv the F'.rtl and 

an enaine-driven vacuum oumo, which aenerates the vacuum 

reouired for ooeration of various control elements. An 

alternative to this svstem, not reouirina a vacuum pumo,. is a 

solenoid valve ocerator. 

'i. .. 
8-4 

Svstem control sensor .requir~ments inclune two temoerature 

sensors, and a control sensor for determinina the need for trao 

reoeneratfon. .,.,emoerature sensors are reauired for ~etectina 

overhea~ina in the trap filter durina the reoeneration, and for 

ensurina that tlie enaine has att:airiea normal ooeratina 

temoerature bet:ore the reaeneration is initiated. 'T'~e sensor 

determinina the nP.e°d for trao reaP.neration could be eit1ier an 

enaine revolution or vehicle mileaae timer, or an exhaust 

hackoressure sensor • 

.,.,he most imoor tan t r eaene rat ion svs tern comoonen t, in terms 

of svstern control, is the r.cu. .,.,he FCU interorets sionals 

r ece i ~1ed from the v.a r i ous sensors in order to main ta in control 

of the reaeneration orocess. 

~s was noted earlier, the reoeneration system for a 

catalvzed trap can he less complex, sfnce the increase in the 

exhaust stream temoerature recruire~ is much smaller. Of the 

seven orimarv hardware components reauired for the 

non-catalvzea trap reoeneration svstem described ahove, onlv 

the svstem.control sensors and the ECU are needed in basicall~ 

the same form for the catalvzen trap reaeneration svstem. 

Some tvoe of auxiliarv air combustion system is still 

reauireCl:fll however, since the exhaust flow thrnuah the 

catalvzed trao is maintained durina tlie receneration orocess, a 

reerl val,7e svstem rnav be adeauate. 'T'he !"lurner heac, exhaust 

diversion svstem, fuel deliverv svstem, ana ionition svstem 

descrihed a~ove are not reauired. 

However, an alternate svstem for orovi~ino a ~oderate rise 

in thi:i temoerature of thP. exf'laust stream is still recruired. 

One such ~ethon, which has been ~uccessfullv tested on a .. ..• . ~.-~:..:·· .. :: ·-::_-_;..... .• -:··-...:-:.;..":~~: . .-• .-~-····-·:.." ... ··:. -.... ~~··- ..:;'1::.--·i:..:; .. ·~~~-:...--~:.i;:_r; ... :,:::;;,·-::;_··~·;.:-.-:::...~ ... ,._ .... ....--~··.,· ·~···"~-""."""'-:; ~ .. ·~· -~ .. .., ___ ---- ..-~----_ ... :;;.· . ...,. 

- ·- -. '°":- '-'~:::! .-:t'T.9J:~-§,w.~ c ~ Q .:;.:s:~B:q . .Q.!:? i,t --:),,11 .. ~·-~·<;.o. n,1,.~ D c; ti o ri..;.. ;...id It-h. ~' -::::';:J,.e ~·.7 .:0.oh..n so.n - Ma~t~.t-.J-1 ev ... :2..."""-' 

cat:alvzed wi.re-mesh trap,_ is ~now.n _as_ .delayed in-cvlinder fuel 

ini~ction. ' small amount of fuel is injected into the 

cvlinrler r1urinq the exhaust stroke, when the cvlinder is too 

cool to ionite t~e fupJ. The injectP.d fuel is carried in the 

exhaust stream to the catalvzerl trao, where it is ignited. 

Since the existino fuel svstel'l is used to in;P.ct t:he fuel, the 

only hardware necessarv is a mechanism for transferrino a 

oortion of the fuel being metered from a "normal" injector to 

the "~elav" injector. 

1'houoh actuallv not oart of the trap or of the 

reaene·ration svstem, one other vehicle modification affectirio 

the exhaust svste~ should be ~i5cusse~ here. .,.,he exhau5t oioe, 

leadino from the enoine to the trao-oxicHzer, will have to be 

fabricated of stainl~ss steel. !f fahrication of this oipe 

us ina normal steel were continuen, oer iod ic reolacement would 
8-5 

he reauired, greatlv increasino 

trap-oxidizer heino removed from 

modification is reouired for all of 

reoeneration svstems ~iscussed. 

II. Licht-Dutv Diesels 

A. Introduction 

the 

the 

the 

_chances of 

vehicle. 

trao desicns 

the 

'!'his 

and 

This section examines the il'!loact of oarticulate control 

for LDDVs anri LDD'T'c;. Since the methodoloov and rnanv of the 

hasic a~sumptions usP.d in this analvsis are the same 0for hot!i 

liaht nutv and heavy nuty, this section contains considerablv 

·more aetail than does·the next section· on heavv-nutv aiesels. · 

~he next subsection estimates the costs, in terms of th~ 

retail ori~e eauivalent (RPB), of each of the basic trao 

de~ians and reaeneration systems described in the 

introduction. These costs are laroelv a function o~ the size 

('1olufT1e) of the trap-oxidizer. This ciiscussion is followed bv 

·suhsections trP.atina the economic imoact on diesel 

manufacturers, the overall cost to the consumer, and the annual 

and -5-vear accreoate costs of these-controls. 

After the costs of the hardware (trap-oxidizer an~ 

reaP.neration system) are estimated, the subsequent analvsis 

examines the economic impact under two requlatory scenarios 

(\.iase and relaxed), and under tt..,io sets of future diesel sales 

oroiections ("best estimate" and "worst case"). The regulatorv 

'scenarios are rescrihed in detail oreviouslv. 'T'he hest 

estimate sales ProiP.ctiorisf31 are exactlv what the cesianation 

i:nolies, while the worst case sales projections are base~ on 

the maximum _increases in diesel sales .. tba~--···appear to .. he · ~ .. ieasonahle: ·· .LT;he ·~t~_rm. -~~cfrs·t.· ca.s:e"/~··r·efers~'··t.o-:·the ·i:moact•· ·o·f~". ........ : .. ·:._ 

increased r!iesel sales on total oarticulate emissions, and the 

re~ultina environmental effects.) 

'T'he cost of the two basic trao-oxitiizers, catalvzed anci 

non-catalvzed, were previouslv estimated in the Regulatory 

Analysis that accompanied the oriainal light-dutv oarticulate 

control reaulations. r41 'T'he model used to estimate the 

manufacturinq costs of each trao desian, which was developed bv 

Lindaren,[51 is aaain used in this analvsis, with cost 

estimates orovided by the trao manufacturers incorporate~ i..nto 

t!"le moi:iel where available. The Lindaren monel for estimatino 

the RP~ of manufacturino costs [51 is· based on the application 

of adjustment factors to the estimated sum of direct !Tlaterial 

and labor, and fixed overhead costs. These factors are 

exoressed as l.n Plus the sum or the adiustment terms, as shown 

below: 
8-i:i 

R'PE = [ (DM+DL+OJ.1') (l+("A+SP) +"'F+LREl ( l+r.A+r'!'+DP) +Rn+'i'F (J.) 

Where: 

DM = 

nL = 

()for = 

CA = 

SP = 

'T''!='. = 

LBE 

CP = 

DP = 

RD = 

= 

Direct ~aterial cost. 

Direct lahor cost. 

Fixed and variahle overhead. 

Coroorate allocation term of ad4ustment factor. 

Suoolier oroFit term of adiustment factor. 

Tooling expense. 

Land and buildina expense. 

r.oroorate profit term of adjustment factor. 

Dealer overhead and profit term of adjustment factor. 

Research and development cost. 

Some of the values used in equation 1 were taken directlv 

from Lindaren's wor'<, [51 while others have been adjusted based 

on more rer.ent analvses. r.11 .~dditional adiustment factors for 

inflation and production volume (i.e., economv of scale) are 

also incorooraten in thi.s analvsis. 'l'hese are described in 

more netail below. 

?eaeneration svstem costs have also '.'-~en estimated in the 

oast. f41 Tn this analvsis, these earlier estimates are 

essentiaJlv suoolanted hv more recent work oerformed hv Mueller 

Associatesr21 under an EPA contract. 

~. 'i'rao-Oxidizer ~vstern rests 

1. Tntronuction and Assu~otions 

·--~ . -·'"- . ,._ .. -~-... !he" Cid ~-u.s tmen t . factors ... f o.r ... i n-f1ation _.a ~d- o r-od uct ion ... volume -- · -·· · ··: :- .::.·- · .::- • :".:ar·e~-:;:oi:r.n:fooenti:en·t .,.~ -o:f·.·,. .. ,.:the 't!'-a·t). r.es~i'cfrV .. '1-' .. or -"·tece·n~e'r·a tTO'n~ ~"sv·st.:em": :::"' 

used. 'T'herefore, these are discussed first, beFore estimatincr 

the soecific manufacturinq costs for each case. 

5ome of the manufacturina cost data that went into the 

development of Lindgren's model and into the previous F.PA 

analvses aates from as earlv as l97A. 'T'hP.refore, an adiustment· 

factor for inflation must be determined. For application to 

oarticulate control hardware, the increase in LDV {new car) 

orices from lq78 throuah 1982 aooears to be a more aoorooriate 

estimate of inflation than t~e rise in the r.onsumer ~rice Tnoex 

over the same time soan. New car orices were 33 oercent ~iaher 

in lq82 than in lq7A, with annual' increases of i:;.2, 7 • .1, 7.5, ~.s:\, ana l.fi oercent in 1978, 1979, 1980, l9Rl, and 1982, 

resoectivelv.ffil ~hese inflntion rates are used in this 

analvsis. 
~-7 

Production volumes of different traps by various trao 

manufacturers are uncertain. 't"he assumotion in this analvsis 

is that two manufacturers will supply trao-oxidizers, and that 

each of them will supply aporoximately half of total production. 

It is also necessary to distinauish between different 

sizes of LDDVs and LDD'!'s, since the size (volume) of the trao 

is deoendent on the enaine size (cHsolacement). In this 

analysis, LDDVs are divided into small, medium, or larae on the 

basis of enaine disolacement. Small LDDVs are those· eauiooea 

with 1.6- to LR-liter (L) enaines, medium LDDVs are eouipoel'i 

with 2.nL to 2.8T. enc:iines, and laroe LDOVs are those with 3.nrJ .. _and larqer enaines. It· is assumed· that - the orojected t;o·ov 

sales will be cHvided aoproximatelv eauallv amonq these thre·e 

size classes. ~he LDDTs are considered to be either small 

(enaines under 4 .1L) or full-size (4. -:it and laroer enaines). 

i:-ull-size tnD"!'s are assumen to sell at a 4:1 ratio to small 

T,f"'O'T'S ·• 

~asen. on the best estimate r.oou sales ?roiectionsr31 and 

the oroiected rates of trao usaae (see Chapter 1), a standard 

. ~veraae.--production level of 2no,nno trnos annuallv for vears 

1987-91, for P.ach of the three r..nov size classes, is a 

reasonahle-e5timate. This P.st1mate would l"'i1Crease if base~ in 

worst case sales projections. 

?rejected averaae annual sales o= small r.Dn'T's are 

a cprox ima te ly ha 1 f those projected for each LDDV size class 

(~ee Chaoter l). 'l'hus the standard aver.:lae trap croduction 

level for small LDDTs is estimated at 100,000 annuallv, or half 

of the standar~ oroduction lP.vel for each LDDV size class. 

Full-size LDD,,.. sales are projected to be rouahlv twice those .. '·: :_ ... f 0 i:~· ··. e·ac'h.· ·:·:r.bo\1 's i .z e -~c:i a:ss 't~ . tffe.re:f 0 re, the'''··'" s tan<i a"ro "' aver a:b'e::·· . 

. oro'au'C:'t·io'n" level of t"r'ap's for ··fuii-s"fze. LDD~s -·is .... estimatecf to" ·~·" 

he ·4nn,nnn. 

In order to develo~ adjust~ent factors based on the 

standard aver aqe oroduc t ion levels· of traps for each of thP. 

five size classes of liaht-dutv diesels, the "learnina curve" 

must be known. For trap-oxidizer prorluction, the learnina 

curve is assumed to be 12 nercent.[41 The learnina curve 

conceot is aoolied to the oroduction levels by first assul'T'inq 

that snme stanrlard averaae oronuction level serves as a 

baseline, for which the oroduction level ad"iustnient factor is 

eaual · to (')ne <i.e., no adjustl'l'ent). rrnaer a J.2 cercent 

learnina curve, doublina the baseline oroduction level leads to 

a 12 percent decrease in per-unit manufactur inc costs, or an 

adjustmP.nt factor of n.R8. C".onverselv, halvina the baseline 

9roduction level leans to a 13. Ii percent increase in cer-uni t 

manufacturing costs, exoressed as an adjustment factor of ·1.136 

n.n;n.88). 
A-8 

Aoolication of the learnina curve to the oroduction of 

trao-oxidizers is done bv assuminq that the baseline standard 

averaae production level is 200,oon traos annuallv, the level 

estimated for each of the three LDDV size classes.· Therefore, 

no adiustment factnr for the level of oroc1uction is aoolied to 

the 2no,noo-trap annual production level assumed for each tnov 

size class. ~he a~iustment factor for full-size LDDTs is n.R8, 

representina a 12 oercent decrease in oer-unit manufacturina 

costs resultina from a c1ouhlina of LDnV trao proC!uction. -i:""or 

small LDDTs· the production level adjustment factor is 1.136, 

reflectinq the oronuction level of small LnDT traos beinc halt 

that of each LDDV size class. 

The oroduction volumes of traos for each size-based class 

of light-duty diesels are all based on the hest estimate sales 

orojections. Tlnder the worst case projections, LDDV oroC!uction 

would double and LDDT production would increase SO percent over 

the best estimate oro:jections. 'T"he effect would be to lower 

per-unit trap manufacturina costs by 12 percent for LDDVs ·and 

hy 6. 2 oerc.ent for LDDTs. 

With the information aiven above, the discussion can now 

he focused on estimating the manufacturing costs of each trap 

desian and of the reaeneration svstems. 

2. Non-Catalvzed (Cornina) ~rao 

~ for~ula for determinina the ~anufacturina costs of 

non-catalvzed trAps has been develooed and used in orevious EPA 

analvses.rl,71 This formula was derived hy relatinc the 

various trap cornoonents to similar or identical components of a 

.. ·-~· . . .,,.,.,_~'!)Qno.-t,t.t.hJr..~-~"·:~-a.t a.,lvs,t~ .. -. , fo_-r-.. ,,. g a~ o_l)~.:.n.e ""::·f.~~-lP.9 "" '· e,Q9 .. i.n e .s , ,-·.. f pr . wb:ic h, :· . :..: ~ .:!'"::.:-.:.· ::~·:-~"co:nt.-i rmed ···.:,-ma.r:i.uf act-u·r i na~·-:·.·.:co st s · -'a··r.e-:· · va.J: re advc~_,,,_._ k:nown·:~·-:- "-'- -~·f,t·e r•~::· 

aoolvina the. ac1i-ustJT1ent -factors, includina those for inflation 

and orocuction volume (hased on the best estimate sales 

orojections) determined in the orecedi!'la section, the formulae 

are: 

For LDDVs: 

RPE = $23 + 0.318(U) ( 2 A) 

For small LDDTs: 

RPF. = $?.f' + n.1c;i::(v) ( 2 "R) 

For full-size LDnTs: 

RP~= $20 + 0.2811('1) 
Where: 

V = the volume of the tr~p, in cubic inches. 

As an example· of apolyina these eauations, consider the 

case of a non-catalvzed trao that was recen·tlv tested 

successfully; by Southwest Research Institute, on a 

~ercede~-Renz 3000. ~his trao had a volu~e of 302 cubic inc~es 

(5.66 inch diameter x 12 inch lenath) ~ substitutinq 1n2 for v 

in eauat ion 2A <for LDDVs) leads to an estimated manu factur ina 

cost ~f about $119. 

As mentioned earlier, traps of various sizes {volumes) 

will be fitted to different sizes of enaines. 'T'rap size can 

looically be exoected to he a function· of volumetric exhaust 

flow of the enaine. (11 While data on the typical volumetric 

exhaust flows of various enaines are not readilv availahle, 

fuel consumotion {the inverse of fuel economv) is an ac'leauate 

· su r roqa te measure. fl 1 'T'he ratios of the f11e i consumot ions., or 

the inverse ratios of the fue 1 economies, over the F't'P {EPA 

urban) drivinc cvcle can he used to extrapolate trap volume 

requirements for other engine sizes, qiven a known reference 

ooint: ~he Mercedes-Benz 3nnn mentioned above has an E?.l\ citv 

fuel-economy ratinq of 26 miles per qallon (mog). 

Projected fuel economies for each of the five size classes 

under consideration, in 1990, are aiven in the table helow: 

.•. :. ~· .. ,· ' 

Size Class 

Small LDDVs 

r.1·ed furn· .. tno,rs ... · · ·- · ·· ·. La r·oe LDo'Vs 

Small tnD'!'s 

Full-size LOOTS 

Encine 

1.6 to 1.AL 

2-. 0 ·to'· -~,...;RL .. 

3. OL arid u·ounder 4.3L 

4.3L and up 

Projected FE 

51.2 mpg . d 3 • 9 

. ·3 7'. 8 

moo . ~ ' . 

mtfo 

dd.8 moo 

33.6 mpg 

't'hese estimates were derived from fuel economv estimates for 

qasoline enaines in 1q90, f31 with a 25 percent improvemen~ 

assumec'l in diesel enaine fuel economv over tlie corresooncHna 

qasoline enqines. 

Usina the Mercedes 3000 {2Ei moo fuel economv, 3<"2 cubic 

inches trap volume) as the reference point, and apolving the 

fuel consumotion ratios as discussed above, the resultina trao 

volume reauirements are: 

,· .:.~ .. •, ! 
Size Class 

Small LDDVs ~ecium LDDVs 

Laree LDDVs 

Sm_all LflD'T's 

Full-size LOOTS 

8-10 

Trao Volume 

153 cubic inches 

179 cubic inches 

208 cubic inches 

17'5 cubic inches 

234 cubic inches 

"!'hese volumes can he suhstituteo for V 

2A-2~, vielding estimated manufacturing costs 

$Rq for small, mP.dium, and larce Lnnvs, and 

small and full~size LDDTs, respectively. 

in the equations 

of S72, $80, and 

$88 and $87 for 

a.s shown in the tahle of traf:) volumes above, the small 

LDD~ trao is projected to reauire a volume only 4 cubic inches 

less than that of the mediulT' LDDU trao. 'T'he medium LDDV trao 

i~ also estimated to cost less to manufacture than the small 

LDD'T' trao, ~~o versus $88. Thus it is more economical to 

produce one tra9, of the size required for medium LDDVs, for 

both meciium LDDV and small Lf'\D'T' aoplications. C"ombining the 

stan~ard average production levels of 2on,ooo annually for 

mei:-lium LJIDVs and 100,0'10 annuallv for STT'all LDD'!'s into a new 

standard averaoe production level of 300,000 traps, the assumed 

12 percent learninq curve lowers the oer-unit cost to $74. 

'T"he manufacturin9 costs oresented above are summarized in 

'T'ahle A-1. ~onfidential estimates of ~anufacturinq costs 

supplie-1 by Cornin9, while not firm, indicate that the 

estimates showr. in 'T'able R-1 are reasonablv ~ccurate. 

; __ .-- ··: ~' ~-,;.:.:·,. ;. IJ.!!g~.r •.. t be ,wo7,q;_t __ ,c;::,q-;5;~,;. ·-~-~l~ s _,,,. pr::.9.Jec ti on s ,c,,· the_ .. co s_:t.: -~~s.t i IT!_a. ~-es " ..... .. - --- ...... -·'-· a:i.. ve 14. a-b.ovi:', -3 re ._ -r'eciuc e-d-.. ·hv 1-2. oe r-'c en t- · for: · ·L nnvs-: - a Ad · ·b-v --· i : 2-' -~ .,. 

oer~ent for tro~s. These estimates are also shown in Ta~le P-1. 

3. ~atalvzec (Johnson-~atthP.V) mrao 

In the Reoulatorv Jl..nalvsis for the iqsc:, lioht-duty diesel 

oarticulate reoulations, r41 the cost of a catalyzed trao was· 

also estimated bv relatino the comoonents of the trao to 

similar or identical components ot a monolithic, ceramic 

catalvtic converter, with washcoat ann noble metals included. 

A formula was then develooed for estimating the manufacturin11 

cost hased on the trao volume. 

,iohnson-~atthev ha:; since publiclv statP.d that the 

Manufacturing cost of their catalytic trao substrate, readv for 

cannino, was $lnn (in l992 aollars) for a trao intended for use 

with a 2.0L enqine. If the volume of this trao is assumed to 

be eaual to that of a trao recentlv tested successfullv on a 

Volkswagen Rabbit with a l.6L enaine (345 cubic inches), then 
8-11 

Table 8-1 

Light-Duty Trap Costs (1983 dollars) 

Best Estimate Sales Projections 

Vehicle Class 

Small LDDVS 

Medium LDOVs 

· t·arge LDDvs· 

Small LOOTS 

Full-Size LOOTS 

Vehicle Class 

Small LDDVs 

Medium LDOVs 

Larqe LDDVs 

Small LDOTS ·-~-···.:·.-;-":': _M ........ ·- •<~..... ',• ·-~ ,., ·· ..... ' ,-.... "°, 

Non-Catalyzed Catalyzed Trap Trac 

$72 $188 

$74 $199 

$89- $246 

$74 $199 

$87 $236 

Worst r.ase Sales Projections 

.. ,:,. .. 

Non-Catalyzed 

Trap 

$63 

$66 

$78 

$66 •• ..:.r -·- -::--;---~;-·-·;·. - :..··;-··· --~- .i~·- ·•·· 

Catalyzed 

Trap 

$lfi5 

$178 

$216 

_ .. c .• · •. ::,:;:_~Jl~:··;- . :::···':'.~.-.-;:.·~.·_-,·· .. -:-·- .. --- ····- ··-::· ... • ........ ":."' .. ::.:: • ~·~~- •• • .. ; •"""' ·- .!: • ·:...~ _ ............... -·-:: .... : •.. ~--- _- _,_,::-.~ ~- ...... ": .. 

$81 $219 
8-12 

the RPE o.f the ma nu f actur ina cost can be determined us inq the 

Johnson-Matthey cost information. The $100-estimated 

manufacturinq cost must first be inflated to 1Q83 dollars and 

then substituted for the non-catalvzed substrate manufacturina 

cost in eauations ·2A-2C. 'T'he effects on the total cost of 

cannina, corporate overhead and profit, and dealer ·mark-up are 

assumed to he unchanaed from the non-catalyzed trap. 

It is assumed that the fixed costs (i.~., toolinq and 

ma ch inerv, fixed overhead) a re the same for both trap types, 

meanina that all variable costs can be expressed as a function 

of trao volume. ~inallv, bv combinina the production of traos 

for medium LDOV~ and small LOOTS as was discussed in the 

orecedina section, the followina equations result: 

For small and large LDOVs: 

RPE = $2) + 0.582(V) (3A) 

For medium· LDOVs and small LOO'T's: 

RPE = $22 + 0.536(V) ( 3 B) 

~or full-size LOOTS: 

~PF. = s20 + o.~nl(V) 

Where: 

v = the volume of the trao, in cubic inches • 

. -.-.'T'he""' -3.:15- cubic-· i·nch- ca-t-alvzed .. trap ;....men:t--i:onedc·· above ·is· e~·ti:t,.a'ted .. fo cost about $·22·4 ~ b·a·se"d ·ofr'!c~e"i~uaTfo'rt":jn_·~ · ~~ se· ·of t·Re-' ...... ' 

l'\ethodoloay developed in the oriainal Feaulatory fl.nalvsis,(41 

with adjustments made for inflation, oro~uction volume, and 

more recent precious rnetal costs, vields an estimaten cost of 

$212 for a 34~ cubic inch catalyze~ trao. 'l'hus incorporatina 

the Johnson-Matthey estimate into the equations 2A-2C chanqes 

th~ estimated overall trao cost bv less. than ~ percent. 

As in the non-catalyzed case, it must he assumed that 

traos of different sizes (volumes) will he oroducea for use 

with different enaines. The 1990 estimated fuel· economies for 

liaht-nuty aiesel~ qiven above are used here, with the 

reference point chanqed to the Volkswagen Rabbit (42 mpq fuel 

economv, 145 cubic inch trao volumel. Aoplvina the ratios of 

fuel consumption as a surrogate rneasure of volumetric exhaust 

flow, as was none in the non-catalyzed case, vields . the 

followinq trap volume requirements: 
Size Class 

Small LOOVs 

Medium Lnrivs and 

small LDD'rs 

Laroe tnovs 

Full-size LOOTS 

8-13 

Trap Volume 

283 cubic inches 

330 cubic inches 

383 cubic inches 

431 cubic inches 

Substitutinq these volume requirements for V in eauations 

3A-3C oives the RPE of the- -inan-ufact.ur-ino cost. The estimated 

costs base'1 on the equations are: $188 for small LT)OV traps, 

$199 for medium LOOV and small LOOT traps, S246 for larae too~r 

traps, and .ff3-,;· for ____ fuii-·size LOOT- traps. These cost estimates 

for catalyzed E~api-ar~-also s~mmarized in Table 8-1. 

~quations 1~-3~ an~ the cost· estimates above are based on 

the best estimate sales projections. ~he impact of the 

"worst-case" sales pro~ections on these estimates is the same 

as on the non-catalyzed cost estimates, with the LDDV costs 

reduced hy l/. percent and the LOO~ costs reduced bv 6.2 percent 

from the f i~ures above. 'l'hese estimates are also shown in 

'l'nb.le- 8-1. 

4. Reaener.ation ~vstem r.osts 

'l'he main co~Ponents of trao reqeneration svstems, for both 

catalyzed and non-catalyzed trap-oxidizers, were described in 

the introduction. 'l'he positive reaene rat ion svstem for 

non-catalvzed traos, which actively initiates the burn-off of 

tlie accumulated particulate by injectino iqnited diesel fuel 

into the exhaust strea~, is dealt with first. ~he costs ... -~.s t,im_a_t.ed. ~[o .. r .. both._ ,r.e.q~n.e.r.~ t.ion ., -~y..:,s.t.eqis aJe. la rael v based.,"· qn , :-.:- ·~ ... ~­

_,".:'.~=the'~. a'n~a.i'.V.~s.Ls~.p~eif.or'med'~-}:)y Mueller .. A,S:s.o.c'iat:es -·,fo"r·" E:P'.&.. ,(2 y.,. . .· .... · .. '; .:.:: .. ,. ; ; ;~ ~~:, .. ;;,._ 

'!'he comoonen ts of both tvpes of reaenP. rat ion system are 

listed, with the estimated RPE of the manufacturing costs, in 

~able 8-2. These estimates are hased on the production levels 

correspondinq to the best estimate sales pro~ections. ~ince 

almost all of the reaeneration system comoonents listed in· 

Table 8-2 are also manufactured for ourooses other than 

particulate control, the pro~uction levels _are hioher than 

those of trap components. On th is increased base production 

level, the impact of the "worst-case" sa~es ?rejections is much 

smaller. Thus, anv chanaes in these esti~ates oue to increases 

in trap-ecruipoed diesei. sales are also much smaller, and are 

not shown in Table A-2. 

T~e hardware comoonents for each tvoe of reaeneration 

system are listea in Table 8-2, and discussed below, in the 

same order as thev were descriheo in the introouction. 
8-14 

Table 8-2 

Liaht-outy Reaeneration 

System Costs (1983 dollars) 

Hardware Item 

Non-Catalyzed Trap: 

Burner Head 

Fuel Delivery System 

Fuel Ignition System* ~uxiliary Combustion Air System 

Exhaust Diversion System* 

System Control: 

Sensors 

ECU'*'* 

Subtotal 

Stainless Steel Exhaust Pipe . Small and Med. LDDVs, small LOOTS 

Large LDDVs, full-size LOOTS 

Total System Cost 

Catalyzed Trap: 

Retail Price 

Equivalent 

$7 

$9 

$5-26 

$30 

$11-14 

$12 

$10 

$84-108 

$16 

$27 

$100-135 

Delaved In-Cylinder Fuel Injection Mechanism $15 

Auxiliary Combustion Air System (Reed Valve) $6 

· ':: io~~:i~ ::::;~~~~.:~.~~~~~() ;.~~r;~r ~,:-~:~. ·"~ -~~:;--..,-~;-~~ :~·;:·,~, :;~·=~-,.-~-·::::=.-. ·:.;.~::: :::~ -~-': -~~ ~-=:::,-_, "~-~:"';,···'Or;: :_-.:;-~$~ii~: :··~~"':. --: 

ECU*'* $10 

Subtotal 

Stainless Steel Exhaust Pipe 

Small and Med. LDDVs, small LOOTS 

Larqe LDDVs, full-size LOOTS 

Total System Cost 

* 

** 

Explanation of cost ranaes appear in the text. 

Derivation of the ECU cost appears in the text. 

$43 

$16 

$27 

$59-70 
8-15 

The burner head is assumed to be fabricated of stamoed and 

welded Type 409 stainless steel, and has an estimated cost of 

$7.(21 · The fuel deliverv system, for supplyinq the fuel to be 

ianited to initiate the reaeneration process, has an estimated 

cost of $9. r21 

'T'wo basic fuel ionition svstems were described in the 

introduction. The more costly svstem (lona-life spark plua, 

steo-ut> voltaoe transformer, ann sianal conditionina 

electronics) is estimated to cost S2f;. [21 While the use of a 

qlow oluq is less exoensive, with an estimated cost of ~S,[21 

it is also less re.liable for ianition when the temperature of 

the exhaust stream is -re la t.ivel v low. Both of these opt ions 

are included in Table 8-2. 

'!'~e reoeneration Process reauires a controlled supolv of 

air to the burner and trap to sustain particulate oxidation. 

'T'he total cost of the auxiliarv air comhustion svstem (pump, 

delivery line, and valves) is- estimated to be $30.[21 

~xhaust must temoorarilv be rerouted around the 

non-ca ta lyzerl tr.ap during reoenera t ion. - The exhaust a i version 

system for accomplishino this is estimate<i to cost between $11 

and $14. [21 'T'he lower cost is for a system utilizing a vacuum 

motor (an ena ine-dr i ven vacuum pumo is assumed to already be 

present on the vehicle), while a system using a solenoid valve 

operator is represented by the hiqher cost (no vacuum oumo need 

be present on the vehicle). 

Svstem control requires the use of several sensors. The 

estimate<i costs are $9, for a sensor to detect. over temperature 

in the filter nurina the reaeneration, and $1, for a sensor to 

:,_.~ . ~P.~~ f~~:~ ~.~p_a ~:~~~~,~~, .~ .e-:(l~rn:~·;.-·n.a~;~~-:i~~t.~~Jit..~d,~,~ ~~tJ'I~· .. ,, .. P.fpper ... , ope.r_a t fn_a,~ :·_:~':~-,.:'~ ~ temperature before reaeneration is in1t1~ted. [21 The sensor 

for determininq the need for trap reaeneration could be either 

an enqine revolution or vehicle mileaae timer, or, an exhaust 

backpressure sensor. 'T'he cost of the former is neql ig ible, [ 21 

while the latter is est imatP.d to · cost no more than $2. r 81 

Since the backpressure sensor is more desirable, however, the 

latter estimate is included in Table 8-2. 

The er itical svstem control component is the electronic 

control unit ('F'C"U) • · i;'or a a sol ine-fueled ena ines, the cur rent 

total cost of an P.CU is approximately $75. [21 Several factors 

make ·this cost inaopropriate for direct use in ~able 8-2. 

First, the current EC"U is typically much more sophisticated 

than is neederl for reaeneration system control. Second, it is 

highly probable that Fr.Us on diesels after 1987 will serve 

several ourposes in addition to their emission control 

functions. (For exam!)le, tsuzu 's 1983 diesel vehicles contain 
8-lf; 

an ErU which functions to improve fuel economy and vehicle 

performance, as well as to control dashboard lighting and other 

miscellaneous devices or "aadqets.") Third, and most 

importantly, continuing advances in microprocessor technoloqv 

can he exoected to further reduce the cost of r.cus in 

constant-dollar terms, while simultaneously widening the scope of potential automotive applications. 

No data are available on manufacturers' plans for the 

installation of Er.us to serve functions other than emission 

;,::.-·· control. A· conservative estimate ·is· that hal·f· of aTl ·to·ovs and LDO~s will be equipped with ECUs, for reasons other than 

emission control, during the period 1987-95. The rema1n1nq 

half of LDDV/LDOT Production would incorporate ECUs in order to 

comply with emission control requirements: however, once 

incoroorated into the vehicle desian thev would certainlv serve 

additional valuable functions. 

"'he r.:cu in the LOOV or Lrmrr of the future wi 11 have four 

pr imarv functions: imorov ina- fuel .. -economv, imorov ina vehicle 

oerformance, device and "qadaet" control, and emission 

control. Allocatinq one-quarter of the total $75 cost to the 

emission control aspects of the FCCT oives an estimated cost of 

approximately $1~ due to particulate control. ·-· . .. -- .. .. . " . . ... 

Assumin9 that half of the F~Us installed for emission 

control will be required solely for particulate control reduces 

the fleetwine averace oer-veh icle cost to $10. If EC"Us are 

installed in mqre diesel vehicles than projected for purooses of NOx control, this estimate may be reduced even further. ........ .., ... .... • • "'1'· ,,,.. ·!. :~:-··\~-- .,:.~t:. •:'.:.: ~ . ..._ -"': .- r ;;i:· •• • .~· • • - • • • : .•• - \.•' .... - \i ".':;: .~;: . .!f ·-:;,.,..,i.... . . • ·- ~;·- .. '1, -.;:.-~. 1"'-:1: ·:..~-... • . ....;- ··~ ~~ ! ·.": • :: .. _..... r~r :·· ~" ~--~ .. :;,, ir.-:. ... , __ .... -~ 

.. ·'· .This - reqene"ratiori-· svstem has a. total estimated RPE of 

between $85 and $109, deoendinq mostlv on the fuel ianition 

svstem chosen. As discussed in the introduction, a stainless 

steel exhaust pipe will also be required for trao-equioped 

vehicles. When a credit for the deleted standard steel exhaust 

oioe is included, the additional cost of this modification is. 

estimated as $16 (for small and medium LDDVs and small LDDTs) 

to $27 (for large LDDVs and full-size LDOTs). 'l'hese costs are 

also shown in Table 8-2. 

,,..he regeneration svstem for a catalvzed trap should be 

less complex than the svstem required for non-catalvzed traps, 

as was exolained in the introduction. While detailed cost 

estimates such as those given above are not available for this 

simpler svstem, the savinas over the "burner system" can he 

estimated usinq the information in Table 8-2. 
8-17 

No burner head assemblv is required. 'T'he fuel delivery 

system is replaced by a mechanism for transferrinq a small 

amount of fuel from the normallv-functioning injector to the 

"nelay" injector. This mechanism is expected to cost about 

$15. r21 'T'he auxiliary air combustion system described above 

can be replaced by .a reed valve (estimated cost $6), [21 since 

the continued exhaust tlow throuah the catalyzed trao dur ina 

regeneration will provide the required suction. · 

'T'he sensors and the ECU, reauired for reaeneration svstem 

·control, are basically identical for either system. The 

st~inless .steel .. ~_x_haqst . _p!pe is also required ._.for ... both .. s~~te~s~- 'T'h~ ccist estimates -t6i these components of the 

catalyzed trap regeneration system are the same as for the 

non-catalyzed case. ~11 of this information is also shown in 

'!'able 8-2. 

5. "'otal ~rap-Oxidizer ~vstem ~osts 

'T"he total cost of the trao-oxinizer svstem is the sum of 

the costs estimated for the trap and for the reaeneration · - ·· ·svst'e-m;·· -siimmaf ies of these costs urider hoth the b.est est.(mate- · 

and the worst case diesel sales Projections are shown in Table 

8-3. 5ince the widths of the ranqes in cost are quite small, 

relative to the absolute costs, only the midpoints of the cost 

ranaes .a.re shown in "'able R-3~-- 'l'hP.se "midcoint" estimates are 

used throuqhout the rest of the analysis. 

It is clear from Tahle 8-3 that, despite the savings 

associated with the reaeneration system, the total cost of the 

catalvzed trap-oxidizer svstem· · i·s· still estimated to be 

... :: _ :-:;;,:;_s u h.S:.t~a n tJ~~JJ:Y.: .... .:mo r~e~- th.9n .. _ t_h at __ .of . the .. _non!'"c a ta lyzed ·:~sys tern·••:"'·~"""'""•":'" 

- -.--. · -s:-ince>"ft:''"Ts'-~con's:1d·eraol v.:-'1ess" ·-e·xt>eWs"i ve ~--and .:acpear·s · to -·be· ·fh·e· .~.-~-· :.~s····· 

oreferred desian of most diesel manufactur~rs, only the cost of 

the non-catalyzed trap-oxidizer svstem is used in the remainder 

of this analysis. 

C. ~conomic rmcact on Diesel ~anufacturers 

In this section, the imoact of the base scenario on 

~anufacturers' light-dutv aiesel sales, capital investments 

and cash flow wlll be analyzea. Only the costs of the 

trap-ox in i zer sys tern and the associated fuel economy penal tv 

are considered here. '!'here are no test facilitv costs 

associated with the base scenario. Certification costs were 

shown to be nealiqi~le in the Reaulatorv Analvsis to the 1985 

carticulate standards.r41 
''eh icle Class 

Small LDDVs 

Medium LDOVS . ~ '·· -~: .... .. .-

Larae r.oovs 

Small LOOTS 

8-18 

Table 8-3 

Total Liaht-Duty Trap-Oxidizer 

Svstem Costs (1983 Dollars) 

Rest Estimate Sales Projections 

Non-Catalvzed Catalyzed 

Trap Trap 

$185 •$246 

$187 $258 ... .,.- ···~·-- .. ... ' .......... ~· 

-

$213 $316 

$187 $258 

Full-Size LDDTs $211 $306 

·Worst Case Sales Projections 

Vehicle Class 

. - . 

Small LODVs 

Medium LDDVs 

Larqe LDDVs 

..... ;~. •• • .1'_~ .. : ":_.,. ·.,··.· -"~:1\1 ilt-.. 

Small LOOTS 

Full-Size LOOTS 

Non-Catalvzed 

Trap 

$176 

$179 

-$202 

Catalyzed 

Trap 

$224 

$237 

$286 

: .. ~;--- .': ~- .. ·$':{7'9. ~ . :-·' .•. • . '• ~ .... 1-:. ·:.,:::..: • ;.._• . •·.·· . ... ...., ....... ·$237 

$205 $289 
8-19 

1. Impact on ~anufacturer's Sales 

'T'he 'imoact of the base scenario on 1 ight-du tv diesel' sales 

depends primarily on three factors. First is the vehicle price 

increase result inq · from the additional cost of ins ta 11 inq a 

trap-oxidizer. 5econd is the fraction of vehicles requirinq 

trap-oxidizers, •o1hich was netermined in r.hapter 1. Third is 

the 1-3 percent fuel economy penalty associated with the use of 

trap-oxidizer technoloav. [91 

The next step is applyina these factors to determine a net 

impact on future diesel sales. This has already been done for 

a number of potent~al combinations of trap costs and trap usaoe 

rates, in .a study per-formed by Jack Faucett Associates (JFA) 

for ~PA(31 usinq consumer information on diesel vehicle 

purchases from Chase Econometrics. [ 10] JFA estimated the 

imoact on LDDV and LOOT sales assuminc;i trap-oxidizer costs of 

$300, $500, and $800, and trap usage rates of O percent, 35 

percent, ,:;s percent, ann 90 percent. An average fuel-economy 

penaltv of 2 oercent for veh·icles equipped with t~aos was also 

incornor a ted. It was assumed that the la rqes t diesel vehicles 

would he eauipped with traps first, the ·medium-size diesels 

next, ana the smallest diesels last, un-t i 1 the over a 11 tr ao 

usaqe rate was met. 

"!'o s impl i fv the aool ica t ion of ,iFA '·s results, an aver age 

trap-oxidizer cost will be used for each vehicle class (LDOV 

and -LDDT). - The trao-oxinizer cosFs for each vehicle size will 

be weiohted bv the relative sales of each vehicle size, as 

estil'lated bv JF'A. £31 'T'his averaae cost is $?.13 for LDDVs, and 

$219 for LDOTs. 

!Ys ina · the averaae trap svstem · costs .. and the trap ~'"":··- ~_, ·::.p.e.ne tr at.ion :r·a-tes;;~ ·:-'fh'e":=~"f u:bfr e:;;, ~'-:'~ai~'s· :·.~· q··r_-=:.:ttl:in.t.•.<;l~-ti~-:-~ d:i e·s.e·1-,"'. :: .: ·· "~,::~;~ ~.!ii ".'--:~"fi.-.: ,....... .!!.-.... ~ - -~~"':~~1-.;-:-··-·· ,-.·~ .... ·-"!'-" _ _,,_~ ·:--• ..,... .... ·"":~·--:~~. ¥- ...... "'J"t., ~ ~-: ..... ~·- ... .- ~.,.... -"t - ~""'h""' ...... : ........ -:--~.. .. .. ,,, . - .. 

vehicles and trucks can be pro)ected by interoolat1on of the 

JFA estimates. Table 8-4 shows the projected sales for the 

"relaxed scenario," where no traos are required on lioht-nuty 

diesels, under both best estimate and "worst-case" diesel sales 

projections. These figures reoresent the maximum number of 

vehicles projected to be sold, as these vehicles do not bear 

the cost of a trao-oxidizer. 

Also shown are the effects of the base scenario on 

light-duty aiesel sales under both the best estimate and 

"worst-case" salP.s projections. ~s can be seen,· the impact of 

the base s c en a r i o i s qr ea t e s t in the ear 1 y ye a r s ( e • g • , 19 8 7 ) 

and diminishes with ti~e. In addition, LODV sales are affected 

more than LOOT sales. ~he larqest impact occurs in 19~7, when 

'30,000 LODV sales are lost (3.4 percent of total LDDV sales 

under the best estimate sales projections). By 1995, this loss 
8-20 

Table 8-4 

Light-Duty Diesel Sales Projections* 

(in thousands) 

Sales and Percent Reduction 

Best Estimate Sales Projections 

Relaxed Scenario 

LDDV Sales 

LOD'l' Sales 

Total: LDDVs and LOOTS 

Base Case Scenario 

LDDV Sales 

LOOT Sales 

Total: LDDVS and LOOTS 

Worst Case Sales Projections. 

Relaxed Scenario 

LDDV Sales 

LOOT Sales 

Total: LOOVs and LDOTs 

·.: ~"ase., c_a_se :.s.cenar io~-'. -""'-'"·'··· . · .• l :·~ 

LDDV Sales 

LOOT Sales 

Total: tDDVs and LOOTS 

* California sales incluned. 

1987 1990 1995 

912 

714 

1,626 

1,300 

1,029 

2,329 

881 (3.4,)** 1,260 (3.2%) 

704 (l.4%) 1,018 (l.0%) 

1,585 (2.5%) 2,278 (2._2,) 

1,824 2,875 

952 1,400 

2,776 4,275 

. -·· ·-. ••• ! 

·- ·- ... 

1,793 (1.7%)** 2,835 ( L 4%) 

94 '2 (l.0%) 1,389 (0.8%) 

2,735 (l.5%) 4,224 (l.2%) 

l,3AO 

1,322 

2,702 

1,355 (l.8%) 

1,310 (0.9%) 

_2,665 .(1.3%) 

3,600 

2,340 

5,940 

. ·:"· ; ............. , .. : . ,, .. :!'~ .... ~•;i.. , ••• 

3,575 (0.7%) 

2,328 (0.5%) 

5,903 (0.6%) 

** Percent reduction in sales from relaxed scenario. 
8-21 

diminishes to 2 c:;, 000 on a much la raer sales base ( l. 8 percent 

of total "best estimate" LOOV sales) • Losse~ of LOOT sales are 

rouahlv one-third to one-half as areat, in the ranae of 10,000 

to 12,000 units annually. 

An underlyina. assumption of this analysis is that the 

manufacturers will pass the total cost of the trap-oxidizer 

svstem on to the consumer. ~anufactuers have heen selling 

diesel vehicles at a premium to consumers willing to pay extra 

for ownership of a relatively new and advantaaeous product.r31 

-Thus- diesel -manufacture-rs have been qenerating higher than 

normal profits on diesel sales, relative to profits on 

comparable gasoline-fueled . vehicles. If this .situation con-tinu.es,.~_-t.hen--ma:nufac.tu·rers-·-m·iaht.,-be able- to ahsorb some· of -

the costs of a trap-oxidizer system bv reducinq their 

above-normal Profit marq in. f.towever, it is expected that the 

premium in the pr ice be inq pa id for diesels will decrease as 

increased competition from other diesel manufacturers brinas 

profit margins down to normal levels. Manufacturers then would 

not he able to ahsor~ the trap-oxidizer cost, and would pass it 

·throuah to the consumer • 

... F.ven .if. die.sel sales de.crease as a result of manufacturers 

addina trao-oxidizer costs to their vehicle sales prices, it is 

unlikely that the automonile industrv as a whole would lose a 

sale. JFA concluded that any consumer deciding not to buy a 

diesel would ourchase a gasoline-fueled vehicle instead. 't'h is 

f. ind ing is not surpr is inq when it is cons irlered that . the 

functions of the two tvoes of vehicles are nearly identical, 

and that only the economics of ownership differ. 'T'hus the 

automobile industrv as a whole should suffer no lost sales due 

to the base scenario particulate control standards. -

"':.~:~-·.: -:~~_ .. ,_ .. ?·~~-: ... _.,.:..::rljv·~s tn:i.e:n t:S;_o..:.~J::~s :a:n_d.-:=-r a ~li-":F.J:ow · E f f.ec ts -.- · -~ -. ~·. - ... ~- ·:. ···- •'· ·-.•. ' . . 

- . . - . - - • . ~ ...... :;..w ..... _,,. .. '. ·'~ ; .... .... ;c:r • 

'T'wo other effects that emission reaulations can have on 

niesel manufacturers are increasing required capital investment 

(i.e., toolina, machinery, research and development (R&Dl, 

etc.) and reducing cashflow. These effects are examined below. 

The bulk of the capital investment associated with the 

reauired use of trap-oxidizers is not exoected to be borne by 

diesel vehicle/enaine manufacturers, but · rather by the 

manufacturers of emission control equipment, such as Cornina, 

NGK, ana ~rohnson-~a t they. 'T'he ca tal vst manufacturers a lreadv 

have developed the necessary substrate technoloav, and the 

diesel manufacturers have shown little interest in this area. ~ven thouah the manufacturers of emission control equipment 

will have to finance the necessarv investments, thev all have 

indicated their willinqness and abilitv to enter this market. 

Thus pre-production investment costs should not be a prohlem 

for any affected entities. 
8-22 

With respect to other investment costs, liaht-dutv 

manufacturers are presently incurring some R&D costs associated 

with· aoplying tra~-oxidizer technolooy to their vehicles. 

Rowever, much of this work has already been completea, an~ 

future R&D should be no less funnable. Thus, R&D ·and capital 

investment requirements should not have a sionificant adverse 

impact on any manufacturers' investment plans. 

Given the above, the only impact on cash flow will result 

from the inventorv of traps, individuallv and on partially 

manufactured vehicl·e.s.. The . time ..... each . trao is held should be 

much 'shorter than ··Eha·t for an entire vehicle, which averages 

about 90 davs. [41 ,,..his turnover period should be short enough 

to not siqnificantlv affect a manufacturer's cash flow. ~or 

example, assuminq an average turnover time of six weeks and 

industry-wide sales of 1. 5 million LDDVs and LDDTs, the value 

of the trap-oxidizers· on hand at any given time would only be 

$37.S million. This is less than $4 per vehicle spread across 

total liqht-duty·sales. 

D. Total Cost to the Consumer 

~he hulk of the total consumer cost of particulate control 

is the increased "sticker orice" of an LDDV or LDD~. Assuminq 

that the full RPE of manu.factur ing cost i5 oassed throuqh tb 

the retail purchaser, the entries of Table 8-3 represent. both 

total trap-oxidizer system costs and the increase in new 

LDDV/LDDT purchase prices due to particulate control. The 

remainder of the total cost to the consumer results from the 

fuel-economy oenalty, and from anv increases in the maintenance 

co.sts. for .. -1 iqh t.-du tv .... diesels result i·nq·-. fr,om·~' "the . -add it ion -o·f ..... ::i·v---~ trap-oxidizer systems. 

Installation of trao~oxidizer systems is expected to 

result in an average fuel economy penalty of 2 percent. [9] 

Estimatina the cost of this penalty over the life of. an 

LDDV/LDDT reauires that the followinq information be 

specified: cost of diesel fuel, discount rate, averaqe vehicle 

miles travelled (VMT) for LDOVs and LOOTS, average LODV and LOO~ fuel economy, and averaqe LDDV and LDDT lifetime. In this 

analysis, the assumptions used are: $1.20/qallon for the 

averaqe cost of diesel fuel: a 10 percent disco~nt rate: 

average annual VMT of 10, 000 for LDDVs and 10, 800 for LOOTS: 

the estimated 1990 fuel economies for each size class that were 

used in determining trap volume requirements: and average 

lifetimes of 10 years for LOOVs and 11 years for LODTs.(11,121 

To calculate the cost of t:he fuel economy penalty, the 

estimated 1990 fuel-economy values (II.~. 2.) are reduced by 2 

percent. Knowledqe of the fuel economy and annual Vf.f'T'. allows 
8-23 

the annual fuel consumption to be determined, which then is 

multiplied by $1. 20/ga llon to yield annual fuel costs. .The 10 

percent discount rate and the lifetime periods are used to 

determine the present value of lifetime fuel expenditures in 

the year of vehicle ~urchase. 

The process is reoeateo without includinq the 2 percent 

fuel-economy penalty, and subtraction of the lower total from 

the higher total aives the cost of the fuel-economy penalty to _-~he consume_r. Carryi_ng_ through these calculation.s,. the. net 

present value of the fuel-economv oenaltv in the· vear of 

vehicle purchase is $33 for small LDDVs, $4fi for medium LDDVs, 

~52 for l~rae_ LDOVs, '41 _f_o_r ~mall LODTs, and $5.5 _for full-size .. : '"· ..:.t6rfr s . ..: ._ · · ' . · - - · · · - ·· - -- - -- . .. · · -- --

Increased maintenance costs will ·result only from 

maintenance of the trap regeneration system, since the trap 

itself is expectea to be maintenance-free and use of the 

trap-oxidizer system· will ~ave no adverse impacts on other 

vehicular maintenance requirements. ~eqeneration system 

maintenance is likely to be limited to replacement of the one 

or both of the temoerature sensors used for system control. -· Th1s "rriaintenan·ce is estimated to requlre about one h-our- -fabor · 

and $10 in new parts, and should only he required once dur inq 

the lifetime of the vehicle. Assuming a labor charge of $2c; 

per hour, the total cost of th is mai.nteiiance is $J5. This 

maintenance should .occur approximately halfway through the 

lifetime of the vehicle, or about five years after the initial 

purchase. Discounted to the year of the vehicle purchase, the 

regeneration svstem maintenance cost is estimated to be $22. 

use of trap-oxidizer systems will. reduce the cost to the 

,,~ ..... :9·Q_r.t~_.μm.~r .. J,p.r _-:1:~xb~.1J.-~t ~~v.s tern ma i nt.e.na nee····- ;·B_v.. ~-u s.:i.m.g-=·,a, ,.s,t.a in-1.e-s,s,• --~·':'·•lL'"·.: ··• .. "~·"'S·t:e·e"l.-.;.:.-e'xha-ust"·'.pioe ··-rto.- discouraqe in-u·s·e·-- :tra~<-remova·tr ,--· .. th'e"'_,.·- "''~·-:..1;.;.,-

need for oeriodic reolacement of the standard steel exhaust 

oipe is eliminated. A conservative estimate of one exhaust 

pipe replacement, at rouqhly the midpoint of the vehicle 

lifetime (5 years), being eliminated results in consumer 

savinqs of $21 (for small LDDVs and LDD'l's, and medium LDDVs) to 

$36 (for larqe Loovs and full-size LOOTS). f 41 As in the 

estimated cosi of re9eneration system maintenance, a 10 percent 

discount rate is assumed. 

The sum of the increased LnOV/LDO"' initial purchase price, 

the .cost of the fuel-economy penalty, and the cost of 

reqeneration system maintenance, less the savings on exhaust 

system maintenance, represents the total cost to the consumer 

of Particulate control. These costs are summarized in Table 

8-5 -for each of the five size classes of liqht-duty diesels, 

and range from $210 to ~266 per vehicle. ·Aaainst the net 
8-24 

Table 8-=i 

Total Cost to ConsUJT'erS of ().min~ and Ooerating a 

Licht-Duty Diesel F..quipped With a Trap-Oxidizer (1983 dollars)* 

Trap-Oxidizer System: 

Best Estimate Sales Projections 

"Worst-case" Sales ?rejections 

.~intenance rests -

Maintenance Savings 

Cost of Fuel Economv Penalty 

Total cost to Consurrer: 

Best Estimate sales Projections 

·~erst-case" Sales Proiections 

Total Cost of c:Mning and 

Operating vehiclefl3l 

Cost tncrease Due to 

Trap-Oxidizer 

Small 

tDI1JS 

$185 

$176 

$22 

($21) 

$33 

~'219 

$210 

$14,l6A 

1.5% 

Medium 

T...00\TS 

$187 

$179 

$22 

($21) 

$4i; 

$234 

$226 

$16,377 

J..'5% 

$213 

$202 

$22 

($36) 

$52 

$266 

$255 

$19,418 

1.4% 

Small 

tool's 

$187 

$179 

$22 

($21) 

$41 

$229 

$221 

Full-Size 

LDO!'S 

$211 

$205 

··s22 

($36) 

$55 

$252 

$246 

All1 · costs ·oa·r·e·::.:a1scountea~"-'fo-· l'vear :'Of'· vehicle.:·.":purchC15~;· .. us1ng.'·'.a .. :~lb.· ~icen't~··i.-r. 

discount rate. 
8-25 

present value of the cost of owning and operatinq an tDDV over 

its lifetime,[13) these costs represent incr~ases of 1.4 to 1.5 

percent. 

B. ~nnual Costs 

'!'he annual costs of the base case scenario are shown, for 

the years 1987 thouah 1995, in 'T'able 8-6. These annual costs 

were ·calculated as the product of the per-vehicle cost to the 

consumer (from Table A-5), the projected sales of LDO~Ts and ·· LDDTs (from Table 8-4), anC'r· the· diesel trap oenetration rates 

(from Tables 1-4 and 1-7 in Chapter 1), using both the best 

estimate and "worst-case" sales projections. -----· -- .. __._ .. __ - - -·-- - - - ------ - ~--· --- --

III. Feavv-Duty Oiesels 

A. tntroduction 

This section is divided into subsections corresponding to 

those in the preceding discussion on light-duty diesels. 

F' i r st, the RP~ of the ma nu f actur inq costs of trap-oxidizers, 

for different classes of HDDEs, are estimated. Second, the 

impact of these costs- on · sales -and t·he capital investment 

requirements of the HDDE manufacturers are examined. Next, the 

increase in the total cost to the consumer of ownina and 

operating an ~DOE due to the particulate control regulations of 

the . base. ca_se is e_stim_ated .• ___ F'.i.nal.ly, the annual costs (for 

1988 throuah 1995) of the base scenario are estimated. All of 

the costs presented in this section are in 1983 dollars. It is 

assumed that 1988 will be the first effective year of 

heavy-duty diesel particulate control reaulations. 

. _ -· . M_μ~tt . .. 9~ . . tJ:!e _rn.~.t}1qg_oJ9gy ~l!Sed .. h~i;:e_ .w~~, d~,scr ibed. in .th_e · ___ . ..... ·: ...!" .. ~~·-- ..... ·- ..... - ..... ·-· .... l, .-.. ~·~ ~ .... .., !!':--• _.... 1 · \,,_ ...... ..,.,. • ..i...\.~ ... 5:..rc?:J..;,•~ -.,;: • ~~.l-.l!!!r•·'t:.r~ . .l.~ ~~·-- ---·•: ~ .. :--::: ! .. - .~ .. .:u._... fi ....... _. ..... " .'!" ... _. •. -· .· ·- .... _. ~· . -"" • ..., .... 

. ::;.~v· .. SP.C::·~:~0n 1: ::o:n·. -1 t·Q.h.t-.~.au ty:.. ::~!:1-1 e sei.s-,; .; , t;he-r·e.fo.r'-e "*"'ff,req.u·e·n t:-: ... r-e fer ence·s "~ ~ u !l: ··-' 

are made to the preceding material. 

B. ~rao-Oxidizer Svstem Costs 

1. Introduction and Assumotions 

Althouqh most heavv-duty emission requlations ~ake 

reference to heavy-duty engines, which are generally tested 

separately on enqine dynamometers in lieu ·of tests on the 

actual finished vehicles, for internal consistency this 

analysis refers to heavy-dutv diesel vehicles (qoovs). 

As was shown previously (I!.B.2.), the trap volume 

required for a given aoolication can be related directly to the 

volumetric exhaust gas flow to be treated. The cost of both 

trao desiqns, catalyzed and non-catalyzed, was then shown to be 

a function of the required trap volume. A similar approach is 

used in this section for heavy-duty diesels. 
8-26 

Table 8-6 

Annual Costs to the Nation of the Base Scenario 

for LOOVs and LODTs (millions of iqg3 dollars) 

Best Estimate 

Sales Projections 

LDDVs LOOTS 

"Worst-Case" 

Sales Projections 

Loovs· LDD'!'s 

Annual Cost: 

1987 52 Hi 95 21 

··l-988 - ·60 ...... :19 -·- - -.. -···-··· 115 23 

1989 61i 20 131 26 

1990 74 22 148 28 

1991 76 23 156 31 

1992 77 25 164 35 

lq93 78 26 172 39 

19'H 7q 27 180 42 

1C)q5 80 2Q 187 46 
8-27 

The estimates of the RPE of manufacturina costs for 

liaht-duty diesels were based on the application of adjustment 

factors to the estimated manufacturinq costs. Additional 

adjustment factors were included in the model developed by 

L indqren ( 51 to comoensa te for inf la ti on and product ion volume. 

With the exception of the adjustments for production volume, 

these factors are unchanged for the heavy-duty case. 

In order to estimate · standard averaqe trap production 

levels_ for __ HDDVs, the number of different trap sizes required _ must be determine~. · ·rri- the Regulatory Analysis for the 

proposed heavv-dutv ~iesel particulate control requlations,[141 

_the_ .?_ssumption _was· that four sizes of traps would be required .. to span the entire ranae of HOOVs. ~he qrouping of HDDVs into 

size classes at that time, based on qross vehicle weight {GVW) 

classes, is shown below: · 

_t:;rlup 

2 

3 

4 

GvW Classes 

IIB*, III, IV 

V, VI 

V!I 

VIII 

In this analvsis, HODVs are divided into only three 

groups, on the basis of both c;vw classes and relative sales. 

Classes VII and VIII ~ODVs are consolidated in one group, and 

Class v is olaeed in the same qroup as Classes IIB-IV. These 

qroups are referred to in the rest of this section as 

medium-duty diesels {MDVs), light heavy-duty diesels (LHDVs), 

and heavv heavy-duty diesels (qHDVs), in order of increasinq 

r,vw. This is summarized below: 

~. > ;:_~: ''"~-~ ... ·.::._;.·-~Gr. O:Up;:.::-,:L ·--~· ... ::- .i,VW.:.C 1 asses. .. - ... ~·v:w .. {.tbs . ) :~. . . ' .... ; .. , .. ·,· ,,, . .-, .. ::·~:-·· .::.: ~:.'.( -·· ::r-i:-.·s. .e_~,-"C" :.;.-.~:·-~>:'" ., ··· .. ~,. ·t~ .;-... t.::. ·'=""~ :~·:- - .-·.:-:.::~' ... > ..:..:~·:; .;.. . -~ ~ .~: ~· .:_-"!·}::·: • • '~- • -.. ~ .. . ~··~- .. '.- .• ~ . ._ .. """., ..:: ~-:.. ·,· .•. '"e. • -~~·.;-:'· :"(.· ;.;~ -~ -- ·; 

MDVs 

LHDVs 

HHOVs 

IIB-V 

VT 

VII-VIII 

~,501-19,500 

19,so1-2~,ooo 

26,001 and over 

These qroups have the advantage that each contains one of 

the three GVW classes that dominate RDDV sales (IIB, VI, VIII), 

while GVW classes havinq relatively low sales are qrouped with 

them through similarity of application. This division is also 

consistent with the diesel manufacturers' typical grouping of 

H'DDVs. ( 15 , 161 

~he standard average production level, for traps for each 

of the three LDOV size classes, was estimated in the precedinq 

* Class IIB in this analysis refers to all vehicles in· the 

traditional GVW Class II {6,001-10,000 lbs.) that BPA 

classifies as heavy-dutv {GVW over 8,500 lbs~, or. frontal 

area over 45 square feet, or curb weight over 6,000 lbs.) 
,·· •• ,. .·!•«ti·".'-

8-28 

section to be 200,000 annuallv. 'T'his fiaure was based on the 

best estimate diesel sales projections[3] and the proiected 

rates of trap usaqe (Chapter l}. These projections also 

indicate that approximately half as many FDDVs will be sold, 

compared to sales of each LDDV size class, in each of the three 

orouos defined above. The standard average product ion level 

for each RDDV grouo .is then 100 ,000 annuallv. 

Fowever, due to the lar~e trap volume requirements for 

LfiDVs and HHOVs, this analysis assumes that two traps (each 

with half the total volume required), will be fitted ·to those 

vehicles. The -stanoard av-eraqe trap production levels are -then - 100,000 for MDVs, and 200,000 each for LHDVs and RHOVs • . Assuming the 12. percent learning curve used in the liqht-dutv 

analysis, the adjustment factors for ~roduction volume are 

1.136 for ~DVs, ano 1.0 (no adjustment) for LHDVs and RHDVs. 

The trap volume requirements are calculated in the 

followino two sections in the same way that the liqht-duty trap 

volume requirements were determined. Trap size is related to 

volumetric exhaust flow, which in turn is proportional to fuel-· 

consumption (inverse of fuel economy). This calculation 

requires estimates for the averaqe new-vehicle fuel economy of 

·each class (MDV, LHDV, HHDV) in the late 1980 's and early 

1990's. Actual projections of 1990 fuel economy for heavv-dutv 

gasoline-powered.vehicles (RD~Vs) [151 were raised by 30 percent 

to account for the increased efficiency of diesel engines, 

giving the projections of 15.5 moq (MDVs), 8.4 mpq (LHDVs), and 

7.n mpg (RRDVs) used in this analysis. These fiqures represent 

1990 project averaqe fuel economies for new heavy-duty vehicles. 'T'hus, they are slightlv higher than t~fuel economy_ oroiections':· use'd' ... in'-' chapte·r -.-:2··~· ·~which· re9i:_e·s.en.t: ··_th.~_ . entl:re-:·· 

h~i~y~d~ty ~ie~ei in-use fleet in iqqo. 

2. ~on-Catalyzed (Cornina) Trap 

.,.he trao volume requirements of non;..catalvzed traps for 

heavy-duty applications are based, as in the liqht-duty case,-

on the successful testing of a 302 cubic inch Corning trap on a 

Mercedes-Benz 3000 with fuel economy of 26 mpq. The trap 

volume requirements that result are 506 cubic· inches for MOVs, 

934 cubic inches for LHOVs, and 1,122 cubic inches for ~HDVs. 

As noter.1 above, the maan i tude of the trap volume 

requirements for LHDVs and HHDVs was hiqh enouqh to assume that 

two traps will be fitted, oer vehicle; with the total volume 

equal to the required size. The individual trap volumes are 

then 467 cubic inches for Lμovs and 5hl cubic inches for HHDVs. 
8-29 

In section II.A.2., formulae were qiven that yielded the 

RPE of manufacturing cost as a function of trap volume. The 

equations 2A-2C, when adjusted for production level as 

discussed in the introduction to this section, become: 

For MDVs: 

RPE = $26 + 0.3~8(V) (4A) 

For LHDVS and FHDVs: ·-

RPE = $23 + 0.318(V) ( 4 B) 

Where: 

v • volume of trap, in cubic inches. 

Substitution of the trap volume requirements for v in 

eauations 4A and 4B qives the RPEs of the heavy-duty traps. 

'T'he 506 cubic inch traps for MDVs have an RPE of about $207. 

For LFOVs, each of the 467 cubic inch tra~s needed has an 

estimated RPE of about $172: the total RPE for two such traos 

(per-vehicle RPE) is $343. The· 56i" cubic inch traps- for ·HHDVs 

have an estimated RPE of about S201 each, with a per-vehicle 

RPE for two such traps of $403. ~11 of these estimates, which 

are based on best estimate sales projections, are shown in 

'T'abl-e 8-7. -· · ·· ---

3. Catalyzed (Johnson-Matthey) Trao 

As in the light-dutv case, calculation of catalyzed trap 

volume reauirements is based on the successful testing of a 345 ··.· ,.,!_""cuhl:c·-·->i-nc-h trap· on·~. a· .. ,.io,lkswac;ren· Rabbit.· .(.f.uel;··.::economy · o·f· ··42,··" --·"·:·:;o~·mpg-:-f ... <rfhe~' projected fue·l ·ec:onomy·-··of ;v:~fr"fo_us· -·HOOVs~~·wa~s-' re°lat'e·a~·.-

to this fuel economy to obtain catalyzed trap sizes. The 

results are: 935 cubic inches for ~nvs, 1,724 cubic inches for 

LHDVs, and 2, 070 cubic inches for HHDVs. 't'he assumption that 

the volume requirements for LHOVs and HHDVs would be met by 

fittinq two traps of equal volume is also used here. ~he 

single-trap volumes are then 8 62 cubic inches for LHDVs and 

1,035 cubic inches for HHDVs. 

t:;quations 3.~-3~ were used in section II .A.1. to calculate 

the RPE of the manufactur inq costs for liaht-duty catalyzed 

traps. T"1hen the adjustment factors for heavy-duty product ion 

levels are applied, the new equations are: 
8-30 

·Table 8-7 

Heavy-Duty Trao Costs (1983 dollars) 

Best Estimate Sales Projections 

Vehicle Class 

LHDVs 

HBDVs 

Non-Catalyzed 

Trap 

$207 

$343 

$403 

r.atalyzed 

Trao 

$636 

$1,051 

$1,252 

Worst Case Sales Projections 

?Jon-Catalvzed Catalyzed 

Vehicle Class 'T'rao 'T'rap 

MD Vs $183 $560 

L~rws $274 $1,007 

HHDVs $403 $1,252 
8-31 

For MDVs: 

R~E = $2n + 0.652{V) {SA) 

~or LHDVs and HHDVs: 

RPE = $23 + O.S83{V) {SB) 

Where: 

v = volume of trap, in cubic inches. 

Therefore the.MDV trao, with a volume of 935 cubic inches, h~s ·an estimated RPE of $636. Each of the 862 cubic inch traps 

for LHDVs has an estimated RPE of about $526, for a per-vehicle 

RPE of $1,051. The RPE of each 1,035 cubic inch RRDV trap is 

estimated to be about $626, or Sl,253 for the two traps 

required. These estimates are all shown in Table 8-7. 

All of the estimates for heavy-duty traps discussed above 

are based on the best estima~e sales projections. Under the 

"wors·t-case" sales projections, sales of MDVs and LHDVs would 

double, with trap production for these vehicles also doubling. 

As was discussed in section I!.'B.l., the 12 percent learninq 

curve assumed indicates that trap costs would be decreased 12 

percent by a doubling of production. Since HHDV sales already 

rePc:esent nearly all sales in GVW Classes VII and VIII, they 

remain relatively constant under both sales projections. Thus, 

the "worst-case" sales projections have an insignificant effect 

on estimated HHDV trap costs. All of this information is 

summarized in ~able 8-7. 

·'-- _.. --~-= ·-s.-e""c_t_i~~~- ~-.-c-: ·- des~-~ib'~a· ..-.the - -d~~o~~~en t·~ ;.·.:~ :f. -~ b~th - ·;~-~a'"i;,;~d · -~ · - ___ ., · 

and non-catalyzed trap regeneration systems. These basic 

svstems will also be used for HDDV applications, with two 

changes that will have an impact on the cost estimates 

presented in Table 8-2. The use of two traps on LHDVs and 

HHDVs means that the quantities required of some regeneration 

system components will be doubled. In addition, the difference 

in the sizes of LDDV and HDDV engines will have an effect on 

the costs of the required stainless steel ·exhaust pipe, as 

discussed later. 

'1'able 8-8 summarizes the estimated RPE of ma nu f actur inq 

cost for both catalyzed and non-catalyzed trap regeneration 

systems, for each of the three qroups of HDOVs. ~he estimates 

shown include the doubled quantity of some of the components 

required for LHDV and HHDV applications. 
8-32 

'!'able 8-8 

Heavy-Duty Reqeneration 

Svstem ~osts (19A3 dollars) 

Hardware Item 

Retail Price Eauivalent 

MODV LHDV HRDV 

Non-Catalyzed ~rap: 

Burner Read 

Fuel Delivery Svstem 

Iqnition System*· -

Auxiliary Comhustion Air System 

Exhaust Diversion System* 

System Control: 

Temoerture Sensors 

ECU 

Subtotal* 

Stainless Steel Exhaust Pioe** 

Total* 

ratalyzed Trap: 

Delayed In-Cylinder Fuel 

Injection Mechanism 

Auxiliarv Comhustion Air 

System- (Reed Valve) 

.· .~.Y~tem Contr:.~.l.:., ., ·'-··. · ·· ·-.··- Sensors · · · ·" · -· 

ECU 

Sub':.otal 

Stainless Steel F.xhaust Pipe** 

Total System Cost 

$7 $14 

$9 $18 

$5-26 $10-31 

$30 $30 

$11-14 $15-18 

$1?. $24 

$37 $37 

$111-135 $148-172 

$33 s·s3 

$143-lfi8 $201-225 

$30 $30 

$Ii $12 

$85 

$33 

$118 

$103 

$53 

$156 

* Bxplanat1ons of ranaes in costs are in section IT.B.4. 

$14 

$18 . 

$10-31" 

$30 

$15-lA 

$24 

$37 

$148-172 

$8.9 

$237-261 

$30 

$12 

. .... ·- $ 2 4· ""'" 

$37 

$103 

$89 

$192 

** For exhaust pioes only, the assumed averaqe production 

volume is 100,000 units. 
8-33 

In section II.B.4. it is shown that, of t·he current $75 

cost of an electronic control unit (FCU) , [ 2] about $10 is 

attrihutable to particulate control on a per-vehicle basis. 

Since ECUs are not projected to be in general use on heavy-dutv 

vehicles before 1988, but will be required under. the base 

scenario, a greater share of the total cost . should be 

attributed to particulate control. This analysis assumes that 

the ECU will be applied solely for emission control purposes, 

and that it will be used for both particulate and NOx control. 

Thus, it's cost is divided equally between particulate and NOx 

control functions, yielding the ECU cost estimate for 

particulate control of $37 shown in Table 8-8. 

--= - .~..,-;_"- The'·-addicional costs of a stainless steel exhaust .. ·plpe - fo~ 

light~duty diesels were estimated (II.B.4.) as about $16 for 4-

and 6-cylinder enqines, and about $27 for 8-cvlinder enqin~s. 

These costs presume a sin9le exhaust manifold with both 4- and 

6-cylinder enqines, and a crossover system with the a-cylinder 

enqine. In the case of RDDVs, the majority of engine exhaust 

systems are the sinqle, non-branching tyoe. Fewer systems are 

of the dual exhaust type, where two entirely separate exhaust 

systems are used.[141 This analysis assumes that all HDDVs in ..... Gvw-~c1a·s·ses IIB-V are manufactured ·with single exhaust systems·, 

while for Class VI . anet l·araer HDDVs, 75 percent are 

manufactured with s inqle exhaust systems and 25 percent with 

dual exh~ust svstems.[141 

In the Draft Reaulatory Analvsis to the Heavy-Duty Diesel 

Particulate NPRM, fl41 it was stated that the ·basic design of 

the LDDV ~-cylinder engine exhaust pipe should be the best 

analogue of the exhaust pipe design of RODVs with sinqle 

exhaust systems. This is also assumed in these estimates. For 

-,;_;-... J~P..Y~~-.; .... ~i t.h.:.:..-_dua,l .. exh,aust sys terns, .. the_. re~.ul_t-i-nq ..,,._co,~t._,~,est-i.ma te,s·:-..!;l._,. .. ,,,..,.,,.,, ... .,~-~ 

, ,. a.r.e- ·-.:do.a bled~"·· •(..-i.e. , -' ·-two- .. stain le S'S ·s tee 1- -e xh aus t · pi pe·s · a'r"e:. · · c:.:n.:~ r~.2" 

assumed to be used) • 

The estimated cost of converting from a standard steel to 

a stainless steel exhaust pipe for an LDDV with a 6-cylinder 

enqine was qiven (II.a.4.) as $16, which included credit for 

the deleted -standard steel pip'!. The corresponding costs for· 

RDDVs are calculated by assumina a direct relationship of 

material cost to engine displacement. The typical LDDV 

6-cylinder engine is assumed to have displacement of 3.7L. The 

typical engine displacements for heavy-duty diesels are assumed 

to be 6.2L (MD~Ts), S3.2t (LRDVs), and 13.9L (!iHOVS). For GVW 

Classes VI, VII, and VIII vehicles (LHDVs and HROVS), the 

average per-vehicle cost is calculated bv assuminq that 75 

percent of these vehicles will require one pipe and 25 percent 

of them will require two, as discussed above. 
8-34 

The _result of these calculations is the estimated 

per-veh.icle average RPE of manufacturing cost for stainless 

steel exhaust pipes: $33 for MDVs, $53 for LHDVs, and $89 for ~rnovs. 

These costs ar~ also shown in Table 8-8. 

exhaust pipes and the doubled quantities of 

the cost estimates in Table 8-2 for 

regeneration systems remain unchanqed in ~able 

s. Total Trap-Oxidizer Svstem Costs 

Except for the 

some components, 

light-duty trap 

8-8. 

The sum of the estimated co::fl:·s- · ·of the tra·o and 

correspondina regeneration system is the estimated - total 

trap-oxidizer svstem cost. These sums are shown, for both trap 

types and under both sets of sales projections, in Table 8-9. 

As was the case in the lioht-duty analvsis, the cost 

ranges are small relative to the absolute costs. Thus, only 

the midpoints of· these ranges are used in Table 8-9 and in the 

remaining analysis. The non-catalyzed trap, which is much less 

·expensive and appears to be the preferred design of heavy-duty 

diesel manufacturers, is the basis of the rest of the analysis. 

c. ~conomic rmnact on Manufacturers 

In this section, the impact of the base particulate 

control scenario on manufacturers' heavy-duty diesel sales, 

capital investments, and cash flow are estimated. As for 

liaht-duty, only the costs of the trap-oxidizer system are 

considered. Certification costs have already been shown to.be-· 

neqli_g~.b~.~ .. Jl4L· ... ~: .. " ._.-_---· .... ,_,, .. . ... - .......... · ·.·-··· · ···· ·· t:. .• • ")f 

1. Imoact on Manufacturers' Sales 

Estimatino the impact of the base scenario on HOD sales is 

considerably more difficult than was the case for light duty. 

There are two main reasons -=or this. First, little research 

has been conducted into the economic elasticities at work in 

the heavy-duty diesel market, and relevant data are scarce. In 

addition, there are complicating factors such as the division 

of heavv-duty diesels into three oroups (MDV, LHDV, HRDV), and 

the relatively insignificant sales of vehicles. in some GVW 

Classes (III, IV, and V). Thus the analysis and estimates 

presented in this subsection must be considered to be, at best, 

rouah approximations. 

The discussion and the estimated impact of the base 

scenario on sales in each HOD group presented in this section 

are based primarily on a report recently prepa.red for EPA by 
8-35 

Table 8-9 

Total Heav·y-Outy Trap-Oxidizer 

svstem Costs (1983 Dollars) 

Best Estimate Sales Projections 

Non-Catalyzed 

Vehicle Class Trap 

MOVs -··· -$ 3-6-3. 

LROVs $556 

HRDVs .. $n52 

Worst Case Sales Projections 

Non-Catalyzed 

Vehicle Class Trap 

p.(0\TS $33_9 

LHDVs $487 

HHDVs $652 

Catalyzed 

Trao 

$754 

$1,207 

$1,444 

Catalyzed 

Trap 

··- - $E'78 

$1,163 

$1,444 
8-36 

Jack Faucett Associates PFA). (171 JFA conducted a thorouah 

literature search and surveyed a number of knowledaeable 

individuals, includ ina members of the heavv-dutv vehicle and 

enaine industries, in order to develop the economic elasticity 

estimates used here. 

~wo kinds of price elasticitv, own-price and cross-price, 

must be considered. Own-price elasticity refers to the chanae 

in the demand for vehicles of a aiven cateqory resultinq from a 

chanae in the purchase price of vehicles in that same 

cateaorv. Cross-orice elasticity takes into account the shifts. 

that may occur,· from diesel to gasoline-fueled enaines or 

conversely, as a result of chanaes in the ourchase or ice of 

vehicles of one or both engine types within a given category. 

In the heavy-du tv market, di st inct own-pr ice elasticities 

exist for each engine type (diesel or gasoline fueled), within 

each GVW class ( IIB th rouqh Vt I I) • .JFA supplied estimates of 

own-or ice elasticity for HDDs in Classes IIB, VI, VII, and 

VIII: no estimates were qiven for Classes III, IV, and v due to 

low sales.[17] These estimates are applied to the three groups 

under consideration her·e by assuming that own-price elasticity 

for MDVs is approximately equal to that of Class IIB alone, due 

to the very low sales of vehicles in the other GVW classes. 

HHDV own-price elasticity is approximated by the sales-weighted 

averaqe of the elasticities of Classes VII and VIII. ~he 

estimates for Class VI are also the estimates for LHDVs, by 

definition of LHOV. 

The best estimate and "worst-case"· sales· orojections, for 

each of the three HOD aroups .. , for 199-0- and. ... 199·5·-are .shown·-.-.in-. 

,c---1'ab1e·. a-fn .. -· on1v:,., ·the:·:~ sales orojections unaer the- relaxea--"= 

requlatory scenario are aiven. Since there is considerable 

uncertainty associate<i with the elasticitv estimates used, the 

impact on sales of the base regulatory scenario are qiven in 

Table 8-10 as percent reductions from relaxed scenario sales. 

Cross-price elasticity is a directional concept, dependinq · 

on whether "from diesel to gasoline fueled" or "from qasoline 

fueled to diesel" is beina considered. In this analysis only 

the former is of interest: Given an increase in the purchase 

price of HDDs in a given category, the own-price elasticity 

estimates how many sales are lost in that cateqory, and the 

cross-price elasticity estimates how many of those "lost" sales 

are compensated for by increased sales of qasoline-fueled 

enqines in the same category. · 

'T'he uncer ta int ies in the cross-or ice elasticity estimates 

used are fairly substantial. Although not shown in Table 8-10, 

the results of using the estimated cross-price elasticities are 

discussed below. 
8-37 

Table 8-10 

Heavy-Duty Diesel Sales Projectio~s 

(in thousands) 

Best Estimate Sales Projections 

Vehicle Class 

MDVs· 

LHDVs 

RHnVs 

1990 

124 

94 

159 

1995** 

170 

126 

186 

Worst Case Sales Projections 

Vehicle Class 

MDVs 

LROVS 

i:·nmvs 

1990 

248 

188 

159 

1995** 

340 

252 

186 

* California sales included. 

Reduction Due. 

to Base Scenario*** 

4.8% 

2.2% 

l·"' 

Reduction Due 

to Base Scenario*** 

4.8% 

2.2% 

1.0% 

** ~hese sales fiqures are extrapolated from EPA sales 

oroiections for 1985 ann 1990. 

*** Percent reouction in relaxed scenario sales, applicable to 

both 19~· and 1995 projections. 
8-38 

Of t'he 4. 8 percent reduction in MDV sales projected to 

occur under the base control scenario, over a third are 

estimated to be made up by increased sales of gasoline-fueled 

enaines in Classes IIB-V. Thus, the net reduction in sales of 

all enqines in Classes IIB-V is estimated to be app~oximately 3 

oercent. SimilarlY., the net reduction in LHDV sales is 

estimated to be approximately 2 percent. For RHDVs, a drop in 

sales of about 1 percent is projected to occur under the base 

scenario, and only about one in 50 of those "lost" sales is 

projected to be offset by new gasoline-fueled engine sales in 

Classes VII and VIII. 

It should also be noted that the own-price and cross-price 

elasticities estimated by JFA were based only on changes in the 

initial purchase Price. ~he effects of increases in operatinq 

and maintenance (O&M) costs are more difficult to incorporate 

into the model. In this analysis, the increase in O&M costs 

(net present value in year· of vehicle purchase, 10 percent 

oiscount rate) . was considered to be part of the initial 

purchase price increase. Although this is not appropriate, 

strictly speaki-na, it is an adequate approximation when the 

uncertainties inherent in the elasticity estimates are taken 

into account. 

2. ~aoital Investment and Cash Flow Effects 

Implement inc a trao-based oarticulate standard for 

heavy-duty diesels should have only minor effects on the 

caoi tal exoend i tures of RDDV manufacturers. The reasons are 

basically ... the same as discussed·· for light-dutv in section . _ I_I_ ·---~ •. , a.n.d a r ~ ...... b.(~._i .. e,.f_l.Y~ ...... r .. e.ca ppe_d .. .... _b.e)~~P-W .• _ - . -~ .... ~ . • 1- ,., · .,., '" •• • ~· •'' ' ••' I~\-. "·}H•, ,.h ,.J -·•' ,v ,,,, .. ,.,.. .~,:.. .:'.: ~ .. ' •• ,'~ ~• ._,, ,, ._ :· ;,,' ,, 

· ••• : o:.: - -.::- ..... : ....... : ;.._-;, • ·... •. • . . •:-..... :!!'. •. I' •• ~ •. ·':!' •• ·-:.:. ··~· 

It is .quite unlikely that any heavv-duty manufacturer will 

chciose to make the necessary investments for the oroduction of 

trap-oxidizers, as the sophisticated technology required has 

alreadv been developed bv other firms. tn addition, the 

production volumes of most individu~l manufacturers will be far 

too small to justify estahlishment of in-house trap-oroduction 

capability. Thus for heavy-duty as well as 1 igh t-duty, the 

bull< of the investments required for trap-oxidizer production 

will be financed by emission control equipment manufacturers. 

Future R&D investments by the manufacturers are difficult to 

estimate, but should not be so high as to adversely affect 

other.investment plans. 

The cash flow impact of these regulations is limited to 

the inventory of traps, individually and on partially 

manufactured HDDVs. This investment is recovered uoon sale of 

the trap-equipped HDDV, and the sales turnover period 9f HDDVs 

is short (generally less than four months). The short 
8-39 

inventory period, and the relatively small amount of cash 

represent-ea, should not sianificantly affect the cash flow of 

any manufacturer. 

o. Total ~ost to the Consumer 

The total cost to the consumer is the sum of the costs of 

the trap-oxidizer system, shown in Table 8-9, and the costs of 

the 2 Percent fuel-economy penalty[4l and increased maintenance 

costs, less any maintenance savings. ~s in the light-duty 

analysis, it is assumed that manufacturers pass all of their 

costs increases throuah to the retail purchaser. 

The costs of the 2 percent fuel-economy penalty are 

estimated by the same methods used for light-duty diesels in 

sect ion II. O. 't'he information used in this calculation is: 

$1. 20 per gallon average diesel fuel cost: 10 percent discount 

rate: new-vehicle fuel-economy estimates of 15.5 mpg (MDVs), 

8.4 mpg (LHDVs), and 7.0 mpg (HHDVs): annual averaqe VMT of 

12,000 (MDVS), 20,000 (LHDVs), and 47,500 (~FDVs): and lifetime 

averaqe Vf.fT of· 120,000 (MDVs), 200,000 (LHDVs), and 475,000 

(oqHOVs) • When this information is used as described ear lier, 

the· net present value of the lifetime fuel-economy penalty, in 

the year of vehicle purchase, is $126 (MDVs), $386 (LHDVs), and 

$917 (HFDVs). This is summarized in Table 8-11. 

The trap should be ma in tenance- free, ..,ut the reqenera t ion 

system will require maintenance once during the lifetime of the 

HDOV, · after approximately five years of operation. For 

light-duty diesels, the discounted cost of regeneration system 

maintenance is estimated at $22 (Table 8-5). This cost should 

be applicable without adjustment to MDVs, which will be 

.. ,equiE=>oed w.ith a sinale .trap •. -. For LHOVs. and ·.·qHOVs, .. with- two··-:···· 

-traps -per· .vehicle·, this est-imate is simply· doubled ·to · $4'-.r.~~~ · ·

1

""""'"· 

Table 8-11 also shows these estimates. 

A maintenance savings will result from the use of 

stainless steel exhaust Pipes, which eliminate the need for 

periodic replacement of standard steel exhaust pipes. On 

averaQe, the total per-vehicle savinas would range from $39 

(MDVs) to $97 (FHDVs) over the vehicle lifetime, using a 10 

percent discount rate and an appro~riate schedule for HDOV 

standard steel exhaust pipe replacement.[14] 

The components of total consumer cost discussed, as well 

as the totals, are shown in Table 8-11. The total consumer 

costs are given for both best estimate and "worst-case" sales 

projections. Also in Table 8-11 is the estimated overall cost 

of owninq and operatina an RHDV over its lifetime, in terms of 

net present value in year of purchase (1983 dollars). [181 A.s 

can be seen, the imoact of particulate control on this overall 

cost is small, about 0.6 percent. 
.. ;· :··~' . 

8-40 

Table 8-11 

Total Cost to Consumers of Owninq 

and Operating a Heavv-outy Diesel Equioped 

with a Trao-Oxidizer (1983 dollars)* 

Trap-Oxidizer System: 

Best Estimate Sales Projections 

ftWorst-Case" Sales Projections 

Fuel Economy Penaltv 

Maintenance Costs 

~aintenance Savinqs 

Total: 

Sest Estimate Sales Proiections 

"Worst-rase" Sales Projections 

Total Cost of Ownina and 

Operating a HHDVf 161 

Cost Increase Due to 

Tr:ap-Oxidizer 

- - -··· -·· ,r 

MDDV 

$3fi3 

339 

$126 

$22 

($39) 

$472 

$448 

LHDV. 

$556 

$487 

$386 

$44 

($61) 

$925 

$856 

HHDV 

$fi52 

$652 

$917 

$44 

($97) 

$1,516 

$1,516 

$274,911 

0.6% 

.. ,,_ . ~-·· ··~ ···, ..... -· .... ~ .::.~. :1_~ -~ 

* All costs are discounted to the year of vehicle purchase usinq a ln percent rate. 
8-41 

E. Annual Costs 

The annual costs of the base regulatory scenario are 

shown, for the vears 1988 to 1995, in Table 8-12. These costs 

were calculated by multi-plyinq the net present value of the 

total cost to the c~nsumer, per vehicle, by annual sales. 

The_ costs summarized in Table 8-12 are shown for two 

possible situations: trap-oxidizers are applied to all F-TDDVs, 

and to only 70 pe~cer:t_t;. o_f RDOVs. As _was discussed in Chapter 

1, the lower trap usage rate would be adequate if emissions 

averaoino is made available to ~DOV manufacturers and 85 

percent efficiency ceramic traps are _used on all trap-equipped 

vehicles. 
8-42 

Table 8-12 

Annual Costs 

to the Nation of the Base Scenario for 

Peavv-Outv Diesels (millions of lq83 dollars) 

Best F.stimate Sales "Worst-~ase" Sales 

Proiections Projections 

Trap Usage Trap usace 

70% 100% 70% 100% 

Annual r.ost: 

1988 239 341 325 464 

1989 251 358 344 491 

1990 262 375 3n2 517 

1991 295 422 402 574 

1992 '' 328 41i9 443 633 . 

1993 361 516 480 li86 

19q4 3q5 564 521 744 

1995 430 614 Sli4 805 

• -- .• j···· •. • .. , . 

. ,, . ... . -
References 

1. - "Trap-Oxidizer Feasibility Study," U.S. EPA, OAN~, 

OMSAPC, ECTD, SDSB, March 1982. 

2. "Estimated Costs of Diesel F.ngine Vehicle Exhaust 

Particulate Filter Regeneration Hardware," Mueller Associates, 

December 7, 1982. 

3. "The Impact of Light-Duty Diesel Particulate 

Standards on the Level of Diesel Penetration in the Light-Duty vehicle and Light-Dutv-Truck Markets," Jack Faucett Associates, 

EPA Contract No. 68-01-6375, November 30, 1982. 

·4. "Requlatory -·-.a.nalysis of 

Particulate Requlations for 1982 

Light-Duty Diesel Vehicles," U.S. 

SDSB, October 1979. 

·the 

and 

EPA, 

Liqht-Duty Diesel 

Later Model Year 

OANR, OMSAPC, ECTD, 

5. "Cost Est.ima t ions for Fmiss ion 

Comoonents Systems and Cost Methodoloqy 

Lindaren, ~PA-460/3-78-00~, March 1978. 

Control Related 

Description," L. 

15. Oral Communication with the Bureau of Labor 

Statistics. 

7. "Summary and Analysis of Comments on the Notice of 

Proposed _Rulemaking for the Control of Light-Duty Diesel 

Particulate Emissions from 1981 and Later ~odel Year Vehicles," 

U.S. EPA, OANR, OMSAPC, ECTD, SDSB, October 1979. 

8. "r.ost Estimations for Emission Control Related Co~ponents/Systems and Cost Methodology. Descriotion--Heavy-outy 

Truck," L. Lindgren, !PA-460/3-80-001, February 198Q. -:-.:~ :.:·: ·- :. • • .. :... -~: ~ ••• - ~·. •• ... ,... -· • • • ~4 • .. • • • ' • - - • • 

7 ""' ., z.~J .' ~ ';. -·""1 • ·• • ••• 

9. The Effect of Trap Oxidizers on Fuel Consumption, 

EPA memorandum from J. ~lson and R. ~anner to Richard A. 

Rykowski, Standards nevelopment and Support Branch April 1984. 

10. "The Future of the Diesel Engine: 

Risk for the 1980's," Chase Econometrics, 

available to the public until March 1983). 

Opportunity and 

June 1982 (not 

11. Determination of useful-Life Values for Light-Duty 

Trucks and Heavv-Duty Enaines, ~PA memo From R. .Tohnson, 

Standards Development and Support Branch To Pubiic Docket No. 

A-81-11, Index No. !V-B-3, Oecember 13, 1982. 

1'2. "Average Lifetime Periods for Light-Duty Trucks and ~eavy-Duty Vehicles," U.S. ~PA, OANR, OMSAPC, BCTD, ~DSB, 

November 1979. 
References (cont'd) 

13. "National Trans po r ta ti on Statistics," Research and 

Special Programs Administration, Department of Transoortation, 

Auaust 1979. 

14. "Draft · Rec:rnlatory 

Par t i cu 1 ate Re q u lat ions , " U. S • 

December 23, 1980. 

Analysis, qeavy-nutv 

EPA, OANR, Ot-1SAPC, ECTD, 

Diesel 

SDSB, 

15. "Th~ Highway Fuel Consumotion ~odel, !ighth 

Quarterly Report," prepared by Energy and Environmental 

Analysis, Inc., U.S. 1Jepartment of Energy Contract No. 

DE-AC01-79PA-70032, Task No. 13, July l, 1982. 

16. "Data Resources U.S. Long-Term Review," TRENDLONG 

0682, Data Resources Incorporated, Summer 1982. 

17. "Estimation of Economic Elasticities in the 

Heavy-Duty Vehicle Market," Jack Faucett Associates, EPA 

tontract No. ~8-01-6375, February 23, 1983. 

- ·· . 18. ·"Operating 

Truckina, July 1981.· 

Costs: Up 20 Percent," Heavy-Duty 
CHAPTER 9 

COST EFFECTIVENESS 

I. Introduction 

Cost effectiveness is a relative measure of the economic 

efficiency of taking an action to achieve a specified goal. It 

is primarily useful in comparing alternative means of achieving 

that goal. In the context of this study, the goal ·is to reduce 

particulate emissions, or perhaps more importantly, to reduce 

ambient levels of particulate where people are exposed. In 

this_ case, .cost effectiveness is expressed in terms of- the 

dollar cost per ton of-particulate emission controlled. 

·-·-· - _ . The p_r_ima~y _ purpQse _of this chapter is to_ determine the 

cost effectiveness of the base scenario for each diesel vehicle 

subgroup so that comparisons among these subgroups can be made, 

and so that these mobile source strategies can be compared on a 

relative bas is to non-mobile source strategies. The baseline 

or starting point for evaluating the cost effectiveness of the 

base scenario is the relaxed scenario, which itself provides 

some level of control. The relaxed scenario was chosen as the 

baseline instead of a totally uncontrolled case for two 

pr ~~c ipal ~~aso_flS_. ··-- ____ _ 

First, the 0.60 g/mi standards for light-duty diesel 

vehicles and trucks (LDDs) have already been implemented. For 

heavy-duty diesel vehicles (HDDVs), compliance with the 0.60 

g/BHP-hr · standard should -··n·o·t oe·c. .;d1-ff icul t and would likely 

preceed a trap-based standard. Because of this, it is most 

appropriate to evaluate the base scenario against the baseline 

which exists at the time these new requirements become 

effecti_ve, i.e., the re_lax~~--~~'!.na_rio_. 

Second,· the· rel·axed · -scenario·· i=tself · repre·sents · a very -' 2 .cc.- • • • ' .. ' ' ,..., r-- ·~ -small degree of control. Al.most all LDDs are already emitting 

at or below the standards. Fleetwide, most HDOs are emitting 

very near the standard. Therefore, there is little practical 

difference between the relaxed scenario and a totally 

uncontrolled case, al though use of the relaxed scenario will 

make the cost effectiveness of the base scenario slightly worse 

than if the uncontrolled case were used. Hence, for both of 

these reasons, it is appropriate to evaluate the base scenario 

as being incremental to the relaxed scenario. (The base and 

relaxed scenarios are described fully in the Introduction.) 
9-2 

To d~termine cost effectiveness, two pieces of information 

are necessary: the costs and emission reductions df the 

s tra teg ies to be examined. 'l'he measure of cost wi 11 be the 

annualized net present value of all purchase, opera tinq, and 

maintenance costs. · Emission reductions will be determined on 

an annual basis in terms of either total, inhalacle or fine 

particulate.* The three classes of suspended particulate as 

examined in order to focus the analysis on the most important 

particulate matter with ·respect to public health and welfare. 

As determin~d in Chapter 6, fine and inhalable particulate have 

the primary ef feet on human heal th. .~s determined in Chapter 

4, only fine particulate affects visibility. As outlined in 

Chapt'er 7, all particulate can participate in soiling. · 

The remainder of this analysis is divided into three major 

sections. 'l'he first section estimates the cost-effectiveness 

($/metric ton) for the base control scenario (relative to the 

relaxed scenario) and concludes with a comparison of these 

figures for the various diesel subgroups on a nationwide and 

urban basis. 'l'he second section of the analysis will estimate 

cost-ef feet i veness values for several stationary sources. The 

third· section will· conclude the analysis by: 1) ap~lyinq a 

discount factor to the cost-effectiveness values for both 

mobile and stationary sources to account for their relative air 

quality impacts, and 2) comparing the cost-effectiveness of 

diesel particulate control to those of stationary sources. 

It should be noted that while cost-effectiveness analysis 

is valuable in discerninq relative economic efficiencies of 

various actions to achieve a specific goal, it cannot provide 

definitive information on the point at which the costs of 

contro.lling any particular source. exc.eed· the econom.ic··. be.ne-fi-ts·." (i.~., dollar value) associated with control. This latter tvpe 0 

of evaluation can be made only by using cost-benefit analysis, 

which is beyond the scope of this report. ~ cost-benefit study 

of mobile source diesel particulate standards has been recently 

completed for EPA under contractfll and the reader is referred 

to that study and others in the literature for more information 

on the benefits of controlling diesel particulate. 

.,, Total particulate is all suspended particulate matter 

reqardless of diameter, inhalahle particulate is 

considered to be all particulate matter less than 10 

micrometers in diameter, and fine particulate is 

considered to be all particulate matter less than 2.5 

micrometers in diameter. 
9-3 

II. Cost Effectiveness of Controllinq Particulate Emissions 

from Diesel Vehicles 

A. ~ethodoloqy 

In this section, the cost effectiveness of proceeding from 

the relaxed to the base scenario for five diesel vehicle 

subgroups will be estimated and compared. These subgroups _ .. _include 1 igh t-duty diesel vehicles {LDDVs) , light-duty - diesel··· - trucks (LODTs), and three subqroups of HDDVs: medium-duty 

vehicles (MDVs), light heavy-duty vehicles (LHDVs), and heavy 

;:.;._hea.vy-duty. veh,,icl"e_s JBHD_~sL,_ .::. . .. - - - .. ····- ·····:~. · 

Most previous EPA cost-effectiveness analyses for mobile 

source emissions have determined cost effectiveness using total 

lifetime costs discounted to the year of vehicle purchase and 

undiscounted lifetime benefits. However, this approach is 

somewhat simplistic,· since . it disregards the fact that the 

emission reductions cannot be obtained at the time of vehicle 

purchase, when the cost of control is determined. ~ecause of 

this, th~ cost-effectiveness value calculated is. entirely 

dependent on the point in time costs are determined, which is 

somewhat arbitrary. 

It would be more appropriate if costs could be allocated - ··to each period of time in which benefits were produced and in ···· 

proportion to the size of these benefits. The result would be 

a cost effectiveness which is applicable at any point in that 

life as well as over the entire life of the vehicle. 

- -This can be done here for mobile sources throuqh the use 

•.n;of ·· two.·'·"'s.implifying 'a·s~sumpt-~ons -· wh_i_c}t _ ~i11:. ·· not -_a'f feet' 1 t·h.,.e ~ 

"'··: accur·acy 'of ·the· -cost-effectiveness compa·r isohs-. · - Ffrst ;-1t ·w'i'lr 

be. assumed that the number of miles a diesel is driven anntially 

is constant throughout its useful life. This simplifies the 

determination of the miles producing emission reductions each 

year. Second, the per-mile emission reduction occurring at the 

vehicle's half life will be assumed to apply throughout its 

life. This assumption allows direct use of the emission 

results of Chapters l and 2, since the analysis there also 

assumed that emissions were constant with mileage except for 

the effect of trap failure. This only results in a slight 

underestimation of emission reductions early in life, with a 

compensating overestimation late in life. The overall effect 

on cost effectiveness is negligible. 

With the use of these two assumptions, the annual emission 

reduction throughout a vehicle's life becomes constant and the 

cost of control can simply be allocated equally (usinq discount 

theory) to each year of the vehicle's life. This latter 
. ~· ::• 

9-4 

annualized cost is simply an annuity equivalent to the total 

cost of control discounted to the year of vehicle purchase, 

which was determined in Chapter 7. <::osts will be addressed 

first and then emission reductions, followed by calculation of 

the cost-effectiveness values. 

B. Costs of Control 

Essentially all of the cost information necessary for the 

cost-effectiveness calculations has been developed in Chapter 

8. Tables 9-5 and 9-11 of that chapter contain detailed cost 

information on the purchase and oper~ting cost impacts fo~ 

LOOVs, LOOTs, and BODVs. These costs are given in 1983 

dollars, discounted at 10 percent to the year of vehicle 

purchase. 

This cost-effectiveness analysis does not require the 

level of disaggreqation given in Table 9-5 for LOOVs and LOOTS 

(e.g., small, medium, and larqe LOOVs as opposed to simply 

LDOVs). Therefore, the costs presented will be combined to 

obtain total -lifetime consumer costs for LDDVs and LOOTs.· ·As 

outlined in Chapters l and 8, the largest vehicles are likely 

to be equipped with trap-oxidizers first, since they are the 

highest emitters. Since the trap usage rates under the base 

scenario (22 percent for LOOVs and 9 percent. for LOOTS) are 

below the projected sales fractions of larae LOOVs (26 percent) and full-size LOOTS {66 percent ) , (21 only the largest size 

vehicles in each class are 1 ikely to have traps. Thus, the 

lifetime costs for these larqest vehicles will be used here. 

_ .. ~- . _ .r.~~_l;_e _, .. ~ .::-: ~ ~-' .sh_q\o!.~ .,.,.~.Q~ _ ..<;1 _i, s.ccn.tn,-~.-~.g.,_ .. : \:Oi;~l life t_ ime. c.on~l.lme r ... ·· .... .:: _·· · ;...,. ~-.e:e s,ts.,, .. f or, -e.ach-·- o,f. ,the f~ive- d i-ese 1 v.ehic=<le q·r:oups. " (HHDV ;ocos·ts·'-''.'·""' 

can be take directly from Chapter 8.} Only those costs for the 

best estimate sales scenarios are shown. ~osts for worst case 

sales would be 0-4 percent lower, because of economies of 

scale. ('Each vehicle class has a different factor since the 

relationship between best estimate and worst case sales is 

different for each vehicle class.) 

These discounted total costs can be annualized (at 

mid-year) over the appropriate average lifetime for each of the 

diesel vehicle classes using present value theory. The 

expected vehicle lifetimes and the resultant annualized costs 

are shown in Table 9-1. 

For tnovs and LDDTs, trap-oxidizers will be used only on 

the portion of each manufacturer's sales necessary to bring the 

manufacturer's sales-weighted particulate levels down to the 

required standard. Since the particulate reduction benefits 

will be measured on a fleetwide basis, but costs shown in Table 
9-5 

Table 9-1 

Base Scenario Costs (1983 dollars)* 

LOOV LOOT MDV LHDV HHDV 

Lifetime r.osts for $266 

Base Scenario 

$252 $472 $925 $1,516 

Vehicle 10 yrs 11 yrs 8 yrs 11.5 yrs 10.5 yrs Lifetime 

Annualized $41 $37 $84 $132 $228 Cost For A 

Trap-Equipped 

Vehicle 

Percent of 22.3 7.6 100 100 100 

Vehicles With 

Trap-Oxidizers 

Fleet Average $9.20 $2.80 $84 $132 $228 Annualized 

Cost Per 

Vehicle 

+ Discounted at 10 percent to year of vehicle purchase, best 

estimate sales. 
9-6 

9-1 only apply to a portion of the fleet, these costs must be 

spread over the entire fleet. This can be accomplished by 

multiplyinq the annualfzed costs of Table 9-1 by the percent of 

vehicles requiring traps (taken from Tables 1-4 and 1-7 of 

Chapter 1). Since the base scenario does not assume the 

availability of an averaging concept for HDOVs, this affects 

only LDOVs and LOOTS. (Without averaging, all HDDVs will use 

trap-oxidizers and no adjustment needs to be made.) These 

fleet-average annualized costs for LDOVs and LDOTs are also 

shown in Table 9-1. With averaging, about 70 percent of all 

HDDVs would require traps and the fleetwide costs shown in 

Table 9-1 would be reduced by approximately 30 percent. 

c. Diesel Pirticulate Emission Reductions 

Calculation of the annual diesel particulate emisson 

reduct ion accompanying the base scenario requires information 

on annual vehicle miles travel led (VM'l') and the emission rates 

under the two control scenarios. Table 9-2 shows the average 

annual mileage for each of the five diesel vehicle subgroups, 

which were derived from each subgroup's average lifetime 

mileaqe and averaqe life (also shown). 

Vehicle particulate emission rates (a/mi) tend to increase 

qraduallv with mileage, in a manner in which can be 

characterized as linear over the life of the vehicle. Thus, 

for either the relaxed or base scenario, one can conceotualize 

a stream of annual particulate emissions, increasing by a 

constant amount each year. If the emissions in each year for 

the base scenario were subtracted from the emissions in each 

year for the relaxed scenario, a stream of emission reductions 

would be created. Costs could then be allocated to this stream . of . .'benefits . ~o p_rovioe a constant and apolicabl.e cost 

effectiveness throughout the vehicle's life. 

As already mentioned 

approximation to this can 

change in emissions with 

reduction at the vehicle's 

and HDDVs is approximately sixth year. · 

in the previous section, a close 

be obtained by ignoring the small 

time and determining the emission 

half life. The half life for LDOVs 

the fifth year~ for LOOTS it is the 

Half-life emission rates for th~ five diesel vehicle 

subgroups were taken from Chapter 2, and are shown in Table 

9-2. Unlike Loos, the half-life emission rates for HDDVs 

differ somewhat for each model year under both scenarios 

because the fuel e ff ic ienc ies and, lience, emission 

characteristics of these vehicles are expected to improve in 

future years. To simplify the cost-effectiveness computations, 

half-life emission rates for 1990 model year HODVs are used. 
9-7 

Table 9-2 

Average Annual Vehicle Miles of Travel 

LOOI r..wr MDCV' UiIX1J HHDOV' 

Average Lifet.iJne 100,000 120,000 110,000 268,000 529,000 Mileage 

Lifetime (years) 10 11 8 11.S 10.5 

AV'erage Annual 10,000 10,900 13,800 23,300 so ,100 Mileage 

Vehicle Emission Rates at Half Life (g/mile) 

telaxed Scenario .270 .280 .818 l.381 2.151 

Base Scenario .204 .261 .381 .642 1.034 

Difference .066 .019 .437 .734 1.117 

Annual Emission 660 210 6,030 17,100 55,960 ?.eduction (grams) 

(metric tons) 6.6 x 10-4 2.1 x lo-4 6.03 x lo+3 0.0171 0.0560 
9-8 

Also, to further simplify the analysis, a sinqle emission rate 

is used to represent Classes IIb and III-V as MDDVs. This was 

determined by sales-weighting the· emission rates for the two 

classes using projections for the 1990 model year from 

Reference 3. These. simplifications have no significant effect 

on the results of tbis analysis. It is also worth noting that, 

for the base scenario, where trap-oxidizers are used on all 

vehicle subgroups to gain the emission reductions, the emission 

rates include the effect of trap-oxidizer failures. 

The annual emission reductions for each diesel vehicl~ 

subgroup can ·~w be calculated by simply finding the difference 

in the emiss_Jn rates from the relaxed and base scenarios and 

multiplying by the average annual mileaqe. These are shown in 

Table 9-2 in both grams and metric tons of diesel particulate 

controlled. 

niesel particulate matter is very small in size, 

mean diameters varying from 0.05 to 0.2 micrometers. 

essentially all diesel particulate · falls into 

particulate cateqory.[4,5,6] Therefore, the 

reductions for total particulate given in Table 

represent the emission reductions for inhalable 

particulate. 

with mass 

A.s such, 

the fine 

emission 

q-2 also 

and fine 

o~ Cost-Effectiveness Values for Diesel Vehicles· 

The cost effectiveness of the base scenario is computed by dividing the fleet average annualized costs . from Table 9-1 by 

the annual emission reductions frorn Table q-2. The resulting 

cost-effectiveness values for the five diesel classes are given - in Table 9-3 in the form of 1983 dollars per metric ton. The 

cost eff~ctiveness of diesel particulate control is essentially 

equivalent for r....oovs and LDDTs (at $13,000-14,000 per metric 

ton), but appears to be better for MDVs and especially LHDVs 

and HHDVs. 

These cost-effectiveness values presume the ava i lab i 1 i ty 

of averac;Jing for LDDVs and LDDTs, but not for MDVs, LHDVs, or 

HHDVs. In Chapter 8, it was determined that HDDV compliance 

costs would drop approximately 30 percent if an averaging 

approach was used. ~evised values incorporating. avera9ing for 

RDDVs _are also shown in Table 9-3. As can be seen, this chanqe 

makes the control of F1DDVs even more attractive relative to 

that of LDDVs or LOOTS. 

It is important to note that these cost-effectiveness 

values consider all emission reductions, regardless of whether 

the reduction occurs in an urban or rural area. Since the 

qreat majority of Americans exposed to violations of t~e NAAOS 
-

- 9-9 

Table 9-3 

Cost-Effectiveness Values 

Total, Inhalable, ·and Fine Diesel Particulate* 

twJ tror ~ LJID!l HRI:1J 

Average $9.20 $2.130 $84 $132 $228 

Annualized 

Cost ($) 

Annual Emission 6.6 x 10-4 2.1 x lo-4 6.03 x io-3 0.0171 

0.0560 

Reduction 

(metric tons) 

Cost Effectiveness 13,900 13,300 13,930 7,740 4,070 ($/metric ton) 

Cost Effectiveness 13,900 13,300 9,750 5,420 2,850 

with Averaqing 

for HOO/S 

($/metric ton) 

Urban cost 23,400 27,200 20,000 11,100 10,600 

Effectiveness 

with Averaging 

for HDOVs 

($/metric ton) 

* Cost-effectiveness values are the same for total, inhalable and fine particulate. 
9-10 

for particulate matter live in urban areas and since diesel 

particulate concentrations are greatest in these locations, the 

control of diesel particulate in urban areas should receive the 

greatest emphasis. This is not to suggest that the be.nefits 

associated with controlling diesel particulate in rural areas 

are unimportant, however. In fact, diesel particulates emitted 

in· rural areas, or transmitted through the atmosphere into 

isolated regions, may adversely affect agriculture, visibility, 

etc. Nonetheless, because urban areas account for the qreatest 

population exposed to NAAQS violations, control of these 

emissions is most important from a public health perspective. 

Hence, evaluating diesel par ti cu late control strategies on an 

urban basis is desirable. 

As estimated in Chapter 2, the five diesel vehicle 

subgroups accumulate different fractions of their annual VMT in 

urban areas: LDDVs, 59.4 percent: LDDTs, MDVs, and LRDVs, 48.8 

percent: and HHDVs, 26.9 percent. Urban cost-effectiveness 

values taking these fractions into account are also shown in 

Table 9-3 with averaging for all classes. A comparison of 

these values shows all five figures to be much more similar 

than before: however, the control of HDDVs still a?pears to be 

more cost effective than that of LDDVs and LDDTs. 

These urban cost-effectiveness values have been developed 

only for comparison among the five diesel subgroups. The 

nationwide cost-effectiveness values of Table 9-3 will be used 

in comparisons with stationary source controls for two 

reasons. First, urban cost-effectiveness values are not 

available for stationary sources. ~econd, the use of urban 

values for only mobile sources would artifically make the cost 

effectiveness of diesel particulate controls appear worse 

relative to that of stationary sources controls. 

III. ~ost Effectiveness of Controlling Particulate Emissions 

from Selected Stationary Sources 

A. tntroduction 

One means of qauging the appropriateness of controlling 

diesel particulate emissions is to compare the cost 

effectiveness of diesel particulate control against the cost 

effectiveness of controlling particulate emissions from 

stationary sources. This section of the analysis will be 

devoted to developing cost-effectiveness values for stationary 

sources. The following section will then develop a methodology 

for converting the cost-effectiveness values derived both here 

and in the previous section into values which are comparable on 

an air qualtiy basis. These latter values will be used in the 

comparison of mobile and stationary source controls. 
9-11 

A total of eight stationary sources have been selected for 

study, based on the availability of control cost information 

and emission reductions on a total, inhalable, and fine 

particulate basis. These eight sources are listed below: 

Source 

Borax Fusing Furnace 

Wet Cement Kiln 

Medium-Sized Industrial Boiler 

Electric Utility Coal-Fired 

Generator 

Kraft Recovery Furnace 

Kraft Smelt Tank 

Rotary Lime Kiln 

Electric Arc Furnace (steel) 

Particulate Control Svstem 

Venturi Scrubber 

Electrostatic Precipitator Baghouse 

Electrostatic Precipitator 

Electrostatic Precipitator Venturi Scrubber 

Electrostatic Precipitator 

and Baghouse 

Baghouse 

Two sets of data and, therefore, two different approaches 

will be used in this analysis. Costs and emission reductions 

for .the first two sources listed above will be developed here 

from data contained in a recently published EPA report on 

control techniques for stationary source particulate emissions 

(herein after referred to as the Control Techniques 

document).[7] Cost-effectiveness values for the last six 

sources listed above have already been developed in a previous 

EPA analysis. [8] These will be used directly here, with some 

adjustments to the costs due to inflation, and, where data 

permits, some adjustment to the amount of the inhalable 

particulate benefits due to a change in the assumed maximum 

diameter for inhalable particulate from 15 to 10 micrometers. 

Thi ~irt(cle size dlstributlons, s6~rce arid e~ission 

control systems characteristics, and costs used in this 

analysis are based on the best available data and are 

representative. of the sources being considered. However, it is 

important to note that all of the values used would likely vary 

from source to source within each source category, so this data. 

and the analysis which follows cannot be routinely applied to 

every individual source. Stationary source emission control 

systems are not standardized, but are designed to meet the 

needs of each. user. ~owever, even with these qualifiers, the 

cost-effectiveness values developed here will serve as a valid 

basis of comparison with the cost-effectiveness of diesel 

particulate control. 
9-12 

B~ Cost Effectiveness of Controllina a Borax Fusing 

Furnace and a Wet Cement Kiln 

1. ~osts of .Control 

Given the necessary information on source and emission 

control system characteristics, Volume 1 of the Control 

Techniques document mentioned above contains a number of 

correlations which can be used to estimate the annualized costs 

of particulate emission control systems. These annualized 

costs include both capital, direct and indirect operating 

costs', and have been developed from data presented in a more 

detailed EPA report. (9] 

The annualized costs given in the Control Techniques 

document cover 8, 700 hours per year of operation, or 

essentially continuous use. ~his is probably unrealistic since 

a normal downtime for scheduled and unscheduled .maintenance of 

approximately 10 percent would· be expected. TJs ing 8, 700 hours 

per year without downtime will tend to improve cost 

effectiveness, since fixed costs remain during downtime but the 

emission reduction is completely lost. However, since no 

accurate estimates of downtime experienced by the various 

stationary sources are available, no adjustment will be made 

here. (Assuming continuous operation happens to also be 

consistent with the manner in which the cost-effectiveness 

values were calculated in the draft HDD particulate requlatory 

analysis, which are addressed in Section C.) 

The Control Techniques document presents costs in January 

1980 dollars. Updating them to 1983 dollars using the producer 

price index for all industrial commodities[lO] leads to an 

annualized cost increase of about 32 percent. 

Table 9-4 presents the annualized costs for the borax 

fusing furnace, the wet cement kiln, and the values of the 

particulate control system parameters used to estimate these 

costs from the previously mentioned figures. In some cases, 

the values for these parameters were taken from the Control 

Techniques document. In other cases, the values were based on 

emissions data in EPA' s Office of Air Quality Planning and 

Standards. ( 11] 

2. Bmission Reductions 

As was done for diesels, "=miss ion reductions for 

stationary sources will be developed on a total, inhalable, . and 

fine particulate basis. Table 9-5 · presents size-specific 

emissions data for the uncontrolled and controlled cases for 

each source. The first column shows particulate conc~ntration 
Sourc:e 

9-13 

Table 9-4 

Parameter Values and Annualized Control Costs 

-for Selected Stationary Source Particulate Controls 

(1983 dollars) 

Control Control System Exhaust Gas 

SVstem Parameters Pate (Am3/sec) 

Borax Furnace Scrubber Delta = 11 kPa 38 

Wet Cem:nt Kiln ESP so.· =120 m2;cm3/sec) 130 

Annualized 

Cost 

' 

$1,170,000 

$1,320,000 
Borax Fusing ~'urnace 

Uncontrolled 

Controlled 

Reduction 

Wet Cement Kiln 

Uocontrolled 

Controlled 

Reduction 

'fable 9-5 

Emissions Data for Borax Fusing 

Furnace and Wet Cement Kiln 

Particulate Size Basis 

Total Inhalable 

Mass 

Concentration 

(m;J/IH:M) 

784 

24.3 

2.02 x 107 

67.4 

Annual 

Emissions 

(ire tr ic tons) 

786 

24 

762 

3.29 x 107 

110 

3.29 x 107 

Mass 

Concentration 

(rrg/CN:M) 

596 

20.6 

14,800 

109 

Annual 

Emissions 

(metric tons) 

598 

20 

578 

24,000 . 109 

23,991 

Fine 

Mass 

Concentration 

(nq/IN:M) 

531 

19 

6,000 

63.l 

Annual 

Emissions 

(metric tons) 

532 

20 

512 

9,770 

103 

9,667 

I I 

\0 

I 

I-' 

""' 
9-15 

in terms of milligrams per dry nominal cubic meter (mq/DNCM) of 

exhaust gas. The annual emission levels were determined by 

multiplyinq the mass concentrations by the exhaust gas flow 

rates expressed in dry nominal cubic meters. These exhaust gas 

flow rates were estimated to be 32 DNCM/sec for the borax 

fusing furnace and ·52 DNCM/sec for the wet cement· kiln using 

the actual exhaust qas flow rates· from Table 9-4 and the 

appropriate adjustment factors for tempera tu re, pressure, and 

moisture content. 

~ow, given the exhaust gas flow rate in DNCM/sec, size 

specific mass concentration in mq/DNCM before and after 

control, and an annual operation period of 8, 700 hours per 

year, the annual metric tons of particulate emissions and 

reductions by particle size can be calculated. Table 9-5 shows 

these annual emission rates on a particle size basis before and 

after control for both the borax fusing furnace and wet cement 

kiln, assuming a constant reduction efficiency with time. 

Subtracting emission rates before and after control gives the 

emission reduction. 

Given the annualized cost values in Table 9-4 and the 

annual emission reduction in Table 9-S, cost-effectiveness 

values on a total, inhalable, and fine particulate basis can be 

determined. These are shown in Table 9-6. 

c. Update of Previously Developed Cost-Effectiveness 

Values 

In previous analyses, EPA developed cost-effectiveness 

values for a number of different stationary sources and . particle sizes. [8] .. These values .. require two adjustments before 

being used in this analysis. First, costs must be updated from 

1980 to 1983 dollars. This can be accomplished using the 32 

;:>ercent change in the producer pr ice index for all industrial 

commodities which was also used above. 

Second, the inhalable particulate emission reductions 

estimated previously also require some adjustment due to a 

change in the assumed cutoff diameter from 15 micrometers in 

the 1980 analysis to 10 micrometers in the present analysis. 

This reduction in emission benefits will in turn lead to an 

increase in the relative cost effectiveness on an inhalable 

particulate basis. 

After reviewing the sources for the original estimates and 

other data developed since that time, entirely new estimates 

for the mass percent of inhalable particulates have been 

developed for the electric utility and the electric arc 

furnace. ~he inhalahle fraction of electric utility 
9-16 

· Table 9-6 

Cost Effectiveness for Stationary Sources[l,21 

(1983 Dollars oer metric ton) 

Particulate Size Basis 

Source Total Inhalable Fine 

Wet Cement Kiln [ 8] 

250 

924 

55 136 

455 

1,452 

4,092 

5,544 

3,168 

2,281 

3,300 

3,055 

Kraft Smelt Tank 

Electric Arc Furnace[3J 

Electric Utility[4J. 

Industrial Boiler[51 

Rotary Lime Kiln (ESP) [6] 

Borax Fusing Furance 

1,254 

1,320 

1,584 

1,532 

1,716 

1,678 

299 

1,440 

1,805 

1,848 

1,980 

2,021 

2,112 

2,145 

Rotary Lime Kiln (Ba9house) [6] 

Kraft Recovery Furnace[7J 

[ l] 

[ 21 

[3] 

[4] 

[SJ 

( 61 

[ 7] 

[ 81 

Ranked according to Inhalable Particulate Cost 

Effectiveness. 

For simplification, the mid?oint of the ranges were used 

where applicable. 

Direct evacuation with 90 ?ercent efficient canopy hood 

versus direct evacuation with open roof. 

High efficiency ESP (0.03 lb/106 BTU} versus lower 

efficiency ESP (0.1 lb/106 BTU). 

Baghouse (0.03 lb/106 BTU) versus cyclone (0.3 lb/106 

BTU). 

qiqh efficiency ESP (0.6 lb/ton limestone) versus lower 

efficiency ESP (0.6 lb/ton limestone) for 500 TPD plant; 

baghouse (0.3 lb/ton) versus lower ~fficienty ESP for 125 

TPD plant. 

High efficiency ESP (99.5 percent) versus lower efficiency 

ESP (99.0 percent). 

Less than $1 per metric ton. 
9-17 

particulate was decreased ·from the 90-100 percent range to 66 

percent based on discussions with OAQPS staff. (111 Electric 

arc furnace inhalable particulate fraction data was adjusted 

from 90 to 66 percent based on data in the Control Techniques 

document. In the other cases, no data were available to make 

any adjustments, so it was assumed that all of the.particulate 

controlled at 15 micrometers or less were also all less than 10 

micrometers. This may overestimate the amount of inhalable 

particulate controlled and, thus, improve inhalable particulate 

cost-effectiveness. However, qiven the absence of data to the 

contrary, this is the best estimate that can be made at this 

time. 

'After adjustments for inflation and the change in 

inhalable particle diameter, Table 9-6 gives the final 

estimates of the cost effectiveness on a total, inhalable, and 

fine particulate basis for the six stationary sources 

previously analyzed and the two sources addressed in Section 

a. They are listed ·in order of their inhalable particulate 

cost effectiveness, from best to worst. .~lso shown is some 

information on the control strategy on which the costs and 

emission reduction benefits are based for the previously 

analyzed sources. 

tV. 1'iscounted Cost Effectiveness for Mobile and Stationary 

Particulate Sources 

A. tntroduction 

As discussed previously, it is desirable to compare 

emission sources based on their relative air quality impacts. 

Ideally, such an evaluation would account for the complex array 

of spatial and temporal characteristics associated with each 

emission source. Such an elaborate study is beyond the scope 

of. this report, however. Instead, an attempt is made in this 

analysis to account for the relative ground level impacts of 

the various sources of p~rticulate by evaluating dispersion 

characteristics. Emphasis is . placed on ground level 

concentrations because the majority of the adverse effects from 

air pollution in populated areas violatin~ the NAAQS for 

particulate matter occur due to ground level exposures (e.g., 

adverse effects on public health). Also, this is an important 

determinant of air pollution since compliance with the NAAOS is 

found by measuring ambient concentrations near . ground level. 

Furthermore, this type of comparative evaluation has 

historically been used by EPA to model the relative 

contribution of various sources to ground level ambient 

concentrations of particular pollutants. (~ore will be said 

about these last two points later.) 
9-18 

Although such an evaluation of relative air quality 

provides a reasonable framework for comparing sources, it is 

nevertheless limited in its scope. For example, performinq the 

analysis in this way ignores the location of these ground level 

concentrations asso~iated with each source, particularly with 

respect to the number of people exposed and the local need for 

control (i.e., is the area in or out of compliance with the 

NAAQS). Unfortunately, this is a significant limitation since, 

for example, stationary sources can often be controlled on an 

individual basis (i.e., where the air quality problems are), 

while mobile sources cannot. This effect results in a relative 

inefficiency of the mobile source approach which cannot be 

factored in at this time. Thus, the conclusion of this 

cost-effectiveness comparison cannot be conclusive. 

The comparison of cost effectiveness on an air qualtiy 

basis will be conducted in three steps. First, it will be 

necessary to determine an express ion which relates the effect 

of various source char act er ist ics on ground level . particulate 

concentrations resulting from a given emission rate. Second, 

the ·pertinent source character is tics for the various sources 

under consideration here and the resultant air quality discount 

factors will also have to be determined. Third, once these 

factors have been determined, it will be ooss ible to calculate 

discounted cost-effectiveness values for all sources which can 

then be compared with those for diesels. 

A. Methodology for Evaluating the Ground Level Impact 

of Stationarv Source Particulate Emi§sions 

There are many characteristics unique to each source which 

can affect its relative contrihution to ground level 

particulate concentrations. The meteoroloq ical conditions of 

the area, particle size and density, release height, and others 

can all affect dispersion. Given that 1) local meteorological 

conditions cannot be taken into account in a study of this 

breadth, and 2) this studv is primarily concerned with 

particulate less than 10 microns in diameter (i.e., similar 

particle-related dispersion), the primary remaining factor 

affecting dispersion is release height. 

In a recently released EPA document, an expression has 

been developed which provides a reasonable approximation of the 

dependence of the maximum ground level particulate 

concentration on effective release height.[121 This 

relationship is provided below: 

W = 10/R for H greater than 10 meters: 

W = 1 for ~ less than or equal to 10 meters. 
9-19 

Where: 

w = discount factor, maximum qround level particulate 

concentration relative to a ground level source, 

H = effective release height, in meters (m). 

This relationship is being used by OAQPS in their 

reconsideration of the NAAQS for particulate matter to relate 

the impact of various emission source controls on ambient 

particulate levels, which are measured near ground level, and 

compliance with the NAAQS. The general concept is also 

analoqous to the use of source discount factors in rollback air quali~y modelling. 

As would be expected, this equation showns an inverse 

relationship between maximum ground level contribution and 

effective release height; i.e., as release height increases, 

.the maximum contribution ~rom this source decreases. 

B. Effective Release Heiqhts and Discount Factors for 

Both Mobile and Stationarv sources 

The effective release height for any emission source is 

equal to the sum of the physical stack height and the vertical 

height which the olume rises before siqnificant horizontal 

dispersion occurs. While stack height is easily measured and 

fixed over time, 9lume rise varies according to source 

character is tics and meteorological conditions (e.g., stack gas 

temperature, exhaust gas flow rate, atmospheric stability, air 

temperature, wind velocity). 

It is intuitively clear that the effective release height 

for diesel vehicles. is less than 10 meters, and when evaluated 

in the equation above, yields the conclusion that diesel 

vehicles can be considered a ground level source (discount 

factor equal to 1.0). However, for stationary sources this may 

not be the case, and effective release height calculations are 

necessary. 

A number of different models to calculate plume rise under 

various atmospheric stability conditions have been developed 

over the past 35 years. One approach which has gained 

widespread acceptance was developed by Briggs and will be used 

here to estimate the plume rise for the eiqht stationary 

sources under consideration. [13] As a further simplification, 

the 'Briqgs formulae for a stable/near neutral atmosphere will 

be used in preference to those for an unstable atmosphere. It 

should be noted that this will tend to improve cost 

effectiveness (low cost-effectiveness values) of stationary 
9-20 

source particulate controls, since particulate dispersion is 

siqnificantly increased during increased atmospheric 

instability relative to that for neutral to stable atmospheres 

and the resulting ground-level impacts would be lowe~ed. 

The Briqqs formulae {shown in Figure 9-1) require 

information on both source and atmospheric characteristics. 

Source characteristic values needed include the exhaust gas 

exit tempera tu re and exhaust gas volumetric flow rate. These 

are shown· in Table· 9-7 along with their sources. Atmospheric 

condftions needed include the ambient air temperature, wind 

velocity, and atmospheric vertical temperature gradient at the 

stack exit. The choice to use an atmosphere with stable to 

near neutral characteristics will dictate values for these 

conditions. The values used here are -2°C/305 m for the 

ambient air temperatu.re lapse rate, 288°K for the ambient air 

temperature at the stack exft, and 5 m/sec for the wind speed 

at the stack exit. These are fairly ~ypical values for a 

midwestern o.s. city under stable to near neutral conditions, 

based on the ICAO U.S. standard atmosohere. The resultant 

plume rise heights are also ~hown in Table 9-7. 

The effective release height is the sum of the stack 

heiqht and the plume rise. Typical stack heights for the 

sources/control systems under consideration are given in Table 

9-7. When these terms are added for the sources under 

consideration here, the effective release heights shown in 

Table 9-7 result. Using these effective release heights and 

the relationship given in the equation above, Table 9-7 qives the values of the weighting factor for the sources/control 

systems under ·con~truction here. ~ote that for diesel vehicles 

the wei~hting factor is 1.0 since the effective release height 

is less than 10 meters. 

C. Air Quality Discounted Cost-Effectiveness Values 

All that remains to be done to estimate cost effeciveness 

on an air quality basis is to divide the cost effectiveness 

values of Table 9-6 by the discount factors of Table 9-7. 

These discounted cost effectiveness values are shown in Table 

9-8. 

The figures in Table 9-8 show that after consideration of 

relative air quality effects, the base scenario is quite cost 

effective relative to stationary source controls regardless of 

the size of particulate examined. While the control of wet 

cement kilns is more cost effective than diesel particu1ate 

control across the board, only one other source is 

significantly more cost effective on a· TSP basis (industrial 

boilers). No other sources are more cost effective o·n a fine 
1. 

2. 

3. 

9-21 

Figure 1 

Plume Rise.Calculation Equations 

·h = 2.3 F 

Us 

1/3 

F = a O (Ts - Ta) 

Ta 

s = ~ Ta 

dT 

dz 

3C0 · 

+ 305m 

,h = plume rise (meters).· 

F = bouyancy flux. 

U = wind speed at stack exit (m/s). 

s = stability parameter. 

g = acceleration of gravity (9.8 m/s2). 

Q = exhaust gas volumetric flow rate (m3/s). 

Ts = exhaust aas exit temperature (°K). 

Ta = ambient air temperature at stack exit elevation (°K). 

dT = ambient air temperature lapse rate. 

dz 
Table 9-7 

Source Characteristic Parameters, Plume Rise, 

Effective l"lelease Height, and WeightiryJ Factor 

Flow Effective 

Control Rate Stack Pll.une Stack Release Discount I I 

Source/Reference System Q(Am3/s) Tenp(°K) Rise(m) Height(m) Height(m) Factor (W) 

Borax Furnace[5,9) Scrubber 38 353 83 12 95 .105 

Cement Kiln[5,9) ESP 30 433 101 46 147 .068 

Electric Utility[5) ESP 533 400 242 175 417 .024 

Industrial Boiler[5) Bag house 163 470 191 55 246 .041 

Electric Arc F\Jrnace[l4) Baghouse 62 346 95 19 114 .088 

Hotary Lime Kiln[l5) ESP 3,000 474 509 30 539 .019 \0 

I Baghouse 800 405 281 25 306 .033 N 

N 

Kraft Furnaoe[l6) ESP 76 430 136 75 211 .047 

Kraft Snelt Tank[l6) Scrubber 7,000 351 470 53 523 .019 
9-23 

Table 9-8 

Summary 

Air Quality Discounted Cost Effectiveness 

Diesel Vehicles and Stationary Sources 

($ per metric ton)* 

Particulate Size Basis 

Source Total Inhalable Fine 

Wet Cement Kiln 

RHDV** 

LRDV** 

MDV** 

LOOT** 

LDDV** 

Kraft Smelt Tank 

Electric Arc Furnace 

Borax Fusinq Furance 

Industrial Boiler 

Kraft Recovery Furnace 

Lime Kiln (Baghouse) 

Blectric Utility 

Lime Kiln (ESP) 

* 1983 dollars. 

1 

2,850 

5,420 

9,810 

13,400 

13,900 

13,200 

10,500 

14,600 

32,200 

35,700 

52,000 

52,250 

83,400 

910 

2,850 

5,420 

9, 810 

13,400 

13,900 

15,700 

16,400 

19,250 

45,100 

45,600 

64,000 

75,200 

104,000 

Ranked according to inhalable particulate cost 

effectiveness. 

2,000 

2,850 

5,420 

9,810 

13,400 

13,900 

23,900 

16,500 

21,700 

135,000 

65,000 

100,000 

170,500 

167,000 

Cost Effectiveness (Table 9-6) divided by Discount Factor 

(Table 9-7) • 

** Assumes presence of emissions averaging. 
9-24 

or inhalable particulate basis. (As mentioned ear 1 ier·, the 

control· of both fine and inhalable particulate are most 

important with respect to protecting the public health, the 

control of fine particulate is most important with respect to 

visibility, and the control of total particulate is most 

important with respect to soiling.) However, because of the 

limitations in the method used to determi:ie the relative air 

quality impact of the various sources, these judgments cannot 

be made conclusively. At best, it can only be said that there 

is no evidence that diesel particulate control is not cost 

effective with resp~ct to stationary source control. 

To further place these figures in perspective, Table 9-9 

shows estimates of annual emissions nationwide for most of the 

source categories listed in Table 9-8. However, the two tables 

do not match up exactly one-to-one. The emission estimates 

apply to entire industrial categories, while in a few cases 

(e.g. , 1 ime kilns and electric arc furnaces) the sources listed 

in Table 9-1 represent only. a fraction of the industrial 

cateqory emissions. ~onetheless, these emission estimates will 

be sufficient for our purposes here. 

The nationwide emission estimates of Table 9-9 can be used 

to compare the potential for emission reduction from the 

stationary sources to that available for diesels. As can be 

seen, the base scenario will ·reduce nationwide emissions by 

roughly 120, 000 metric tons per year in 199 S. Only three of 

the stationary sources being considered here could potentially 

provide the same emission reduction: electric utilities, the 

cement industry, and industrial boilers. Given that the cement 

industry is predominantly located in rural areas, [ 171 only the 

remaining two sources can produce the same emission reduction 

where it is most needed. In addition, the impact of these 

sources on qround-level ambient concentrations relative to that 

of diesels must also be kept· in mind. 

V!. Summary 

The cost effectiveness of the base scenario relative to 

the relaxed scenario has been estimated for five classes of 

diesels. For the purposes of comparing control between the 

diesel vehicle classes, cost-effectiveness values were 

determinerl on both a nationwide and urban basis, as well as for 

the c~ntrol of total, inhalable and fine particulate. The cost 

effectiveness of controllina stationary source particulate· 

emissions was also estimated. In order to compare these varied 

sources aaainst the 9oal of improving air quality, emission 

control effectiveness was discounted according to the effective 

release height of the emission and its effect of dispersion. 

While this methodology accounts for source-specific dispersion 
9-25 

Table 9-9 

Annual Nationwide Emission Rates by Source Cateqorv 

s·tationarv Source (1981) [181 

Electric Utillties 

Cement Industrv 

Industrial Boiiers 

Concrete, Lime, Gypsum Industry 

Pulp Mills 

Iron and Steel Foundries 

Borax Furnaces 

· On-Highway Di~sels 

(best estimate sales) 

1980 

1995 Relaxed Scenario 

Base Scenario 

Metric Tons Per Year 

1,000,000 

46.0, 000 

400,000 

140,000 

110,000 

50,000 

Unavailable 

Metric Tons Per Year 

140,000 

285,000 

166,000 
9-26 

effects, it does not account for important factors such as the 

location of the air quality improvement. This is a significant 

drawback, and prevents a fully appropriate comparison from 

being made. 

The results of the analysis indicate that on an air 

quality basis the control of diesel particulate is cost 

effective relative to stationary source controls reqardless of 

whether fine, .inhalable, or total particulate are considered. 

However, due to the 1 imitations of the methodology, the best 

that can be said at this time is only that there is no evidence 

that diesel particulate control is not cost effective with 

respect to available stationary source control and that the 

control of diesel particulate should not be avoided due to 

cost-effectiveness concerns. Between the subgroups of diesel 

vehicles, on an urban hasis (the most appropriate) and assuminq 

the presence of averaging, HHDVs are the most cost effective to 

control, followed by LHDVs, MDVs, LDDVs, and LDDTs. 
9-27 

References 

1. "Health, Soiling, and Visibility Benefits of 

Alternative Mobile Source Diesel Particulate Standards," Final 

Report, EPA Contract No. 68-01-6596, Mathtech, Inc.,.Princeton, 

NJ, December 1983. 

2. "The Impact of Light-Duty Diesel Particulate 

Standards on the Level of Diesel Penetration in the Light-Duty 

Vehicle and Light-Outv Truck Markets," Jack Faucett Associates, 

EPA Contract No. 68-01-6375, November 30, 1982. 

3. "The Highway Fuel Consumption Model: Eighth 

Quarterly Report," Energy and Environmental Analysis, Inc. for 

U.S. DOE, Contract No. OE-AC01-79PE-70032, July 1982. 

4. "Particulate Size Variation in Diesel Car Exhaust," 

Groblicki, P., and c. Begeman, SAE 790421. 

S. "Characterization of Diesel Exhaust Particulate 

Under Different Engine Load Conditions," Presented at 7lst 

Annual Meeting of APCA, Schreck, R., et.al., June 25-30, 1978. 

6. "Characterization of Particulate and Gaseous 

Emissions from Two Diesel Automobiles as Functions of Fuel and 

Driving Cycle," Rare, c. and T. ~aines, SAE Paper No. 790424. 

7. "Control Techniques for Particulate Emissions from 

Stationary Sources," Vols. 1 and 2, U.S. ~PA, OANR, OAOPS, 

F.PA-450/3-81-00Sa and b, September 1982. 

8. "Draft Regulatory Analysis, ~eavy-Duty Diesel 

Particulate Regulations," U.S. EPA,-OANR, OMS, ECTD, SDSB, 

December 23, 1980. 

9. "Capital and Operating Costs of Selected Air 

Pollution Control Systems," U.S. EPA, OANR, OAOPS, 

EPA-450/5-80-002, December 1978. 

10. Figures gathered by the Bureau of Labor Statistics 

and compiled in the February 1983 "Economic Report of the 

President." 

11. Extracted from selected Fine Particulate Emissions 

Inventory System data. 

• 

12. "Draft of Requlatory Impact Analysis for Proposed 

Revision of National Ambient Air Quality Standard for 

Particulate Matter," 
9-28 

References (cont'd) 

13. Air Pollution, McGraw Hill Book Company, Perkins, 

lot., 1974. 

14. "Background Information for Standards of 

Performance: Electric Arc Furnaces in the Steel Industry, Vol. 

1: Proposed Standards," u.s. EPA, OAWM, OAQPS, 

EPA-450/2-74-0l7a, October 1974. 

15. "Standards Support and Environmenal Impact 

Statement, Vol. l: Proposed Standards of Performance for Lime 

Manufacturing Plants," U.S. EPA, OAWM, OAOPS, 

EPA-450/2-77-007a, April 1977. 

16. "Standards Support and Environmental Impact 

Statement: Vol. 1: Proposed Standards of Performance for 

Kraft Pulp Mills," U.S. EPA, OAWM, OAOPS, September 1976. 

17. Information Concerning Particulate Emissions from 

Non-Mobile Sources, ~emo from R. ~eligan to C. Gtay, u:s. EPA, 

July 11, 1979. 

18. "National Air Pollutant Emission Estimates, 

1970-1981,." U.S. EPA, OANR, OAQPS, EPA-450/4-82-012, September ---

1982. 
CHAPTER 10 

·SENSITIVITY 

!. Introduction 

This chapter contains a variety of analyses intended to 

address the sensit~vity of the previous technical analyses to 

key assumptions that were made. The first analysis addresses 

the assumed levels of the LDV and LDT NOx standards. While the 

current NOx standard were presumed to continue indefinitely for 

ease of analysis, this is actually not likely to be the case. 

As additional NOx control tends to increase enq ine-out 

particulate levels, more stringent NOx standards would increase 

emissions under the relaxed scenario and increase the number of 

traps required under the base scenario. The cost effectiveness 

of trao application would also be affected. 

The second analysis has a two-fold purpose. One, it 

addresses the assumption that the analysis of the base 

scenario, which only requires a minority of LDDVs and LOOTS to 

he equipped with traps, adequately addresses the economic 

viability (cost and cost effectiveness) of trap-oxidizer usage 

in general. Two, it expands the previous benefits analyses by 

estimating emissions (and, thus, other environmental effects) 

under the stringent particulate control scenario. 

An intermediate control scenario for LDOVs and LOOTS is 

examined in the third analysis. This scenario, requiring the 

application of advanced non-trap technology, falls between the 

relaxed and the base scenarios in terms of strinqency. 

The fourth analysis addresses the possibility of using HOD I emissions under the relaxed scenario as an estimate of 

uncontrolled emissions, which is usually desirable to present 

in a regulatory analysis. 

The f.ifth analysis assesses the effect on diesel 

particulate emissions resulting from having no growth in future 

diesel sales. This provides a .lower bound on the emission 

estimates which have been analyzed in the previous chapters. 

The first two analvses will be presented together, as they 

overlap technically to a significant deqree. The third, 

fourth, and fifth analyses will follow. rt should be noted 

that these analyses will only address c~rtain basic features of 

each. scenario, such as fleet emissions, trap usage and cost 

effectiveness. ~ore advanced aspects, such as exposure, cancer 

risk, and economic impact, are not presented. This was done 

because all of the benefits described in this study are 
10-2 

proportional to fleet-wide emissions in a given calendar year, 

except for visibility effects, which are nearly proportional in 

the ranqe being examined. Thus, the sensitivity of urban 

emissions in the sensitivity analyses indicates the same 

sensitivity in any other benefit category. A quantitative estimate of any or all benefits under one of the new scenarios 

being analyzed here can be determined simply by applying the 

ratio of fleetwide urban emissions to the estimate of benefits 

under one of the scenarios analyzed in the previous chapters. 

The same is true for economic impact, which is essentiallv 

proportional to the fraction of vehicles with traps. -

I!. Liqht-outy NOx Standards and the Stringent Control Scenario 

The previous chapters assumed that the NOx standard for 

LOVs and LOTS would remain at 1.5 and 2.3 g/mi, respectively, 

throughout the time period covered by this study. !n this 

section, three additional sets of LDV/LDT NOx standards are 

investigated: 1) 1.0/l.2 g/mi, 2) 1.5/1.7 g/mi, and 3) 

2.0/2.3 g/mi. 

·In addition,· the previous chapters only addressed two 

control scenarios, the relaxed and the base scenarios. Here, a 

third scenario, the strinqent scenario, will be examined. rt 

consists of full, trap-based standards of 0.08 g/mi for LDDVs, 

0 .10 g/mi for LOOTS, and 0. 10 g/B~P-hr for ~ODs. The LOOV 

standard of 0.08 g/mi is that promulgated by California for the 

1989 model year. The LOOT and HOD standards follow from this 

level in that they require the same percentage reduction from 

the base scenario. 

·~our key . aspects of these scenarios will be addressed. 

The first aspect addressed will be manufacturers' corporate 

average particulate standard levels associated with the relaxed 

scenario under the three sets of NOx standards. The second and 

third aspects are directly related, the fraction of vehicles 

requiring traps under the base and strinaent scenario, and 

urban particulate emissions in 1995 under the relaxed, base, 

and stringent scenarios under the various NOx standards. The· 

fourth aspect will he the cost effectiveness of the base and 

stringent scenarios under the various NOx standards. 

A. Manufacturers' Corporate ~veraae Standard Level 

The methodoloqy used to estimate each manufacturer's 

current (relaxed scenario) corporate average standard level 

under NOx standards of 1. 5 and 2. 3 q/mi for LDVs and LOTs, 

respectively, was presented in Chapter· 1. There, each engine 

configuration's low mileaqe particulate emission level was 

first adjusted for the NOx emission level under consideration. 
10-3 

This was accomplished through the use of estimaterl 

NOx/particulate tradeoff curves. The slope of the curve for 

small LOOV enqines (1.6-1.8 liters displacement) was -0.033 for 

NOx values less than or equal to 1. 3 5 g/mi and zero for NOx 

values qreater than 1.35 g/mi. For medium LDDV engines (2.0 to 

2.8 liters displacement), the slope of the curve was -0.20 for 

NOx values less than or equal to 1. 3 5 q/mi and -o·.10 for NOx 

values greater than 1.35 g/mi. For larqe LDDV engines, the 

slopes were -0.40 and -0.10 for NOx values less than and 

greater than 1.35 g/mi, respectively. The slopes of the 

NOx/particulate tradeoff curves were the same for LDDTs. 

However, small LODTs have displacements from 1.6 to 2.3 liters 

and full-size LOOTS have displacements of 6.2 liters. There 

were no "medium• LOOTS. 

Once each engine configuration's low-mileage particulate 

emission level was estimated, its particulate standard level 

was determined bv multiplying the particulate emission level by 

its deterioration factor and the safety factor. Each 

manufacturer's engine configurations were then sales-weighted 

to give that manufacturer's corporate average standard level. 

· This methodoloay was repeated here for more stringent NOx 

standards ( 1. 0/1. 2 a/mi for LOVs and LOTS, respectively) and 

also for more relaxed ~Ox standards ( 2. 0/2. 3 g/mi LDVs/LO'T"s) • 

Tables 10-1 and 10-2 show each manufacturer's corporate average 

particulate standard levels associate with the relaxed scenario 

for LOOVs and LOOTS under the various NOx standards. For 

LOOVs, qoing to a 1. 0 g/mi NOx standard from a 1. 5 q/mi NOx 

standard increases particulate emissions more than twice as 

much as going from a 2.0 g/mi NOx standard to a 1.5 g/mi NOx 

standard. The effect of moving to a 1.2 g/mi from a 1.7 g/mi NOx standard for LOOTs is small for small tnOTs but is dramatic 

for full-size LOOTs. The impact of moving from a 2.3 g/mi to a 

1. 7 q/mi ~Ox standard is negligible for small LDDTs but is 

measurable (18 percent increase) for full-size LOOTS. These 

impacts will reappear below when the effects of various NOx 

standards on urban emissions under the relaxed scenario are 

considered later in this section. 

In applying th is methodology to the stringent NOx 

standards (1.0 g/mi for LDVs and 1.2 g/mi. for LOTs), the 

estimated NOx/particulate tradeoff curves were based on 1983 

certification data, most of which were at higher NOx levels, 

and extrapolated to obtain these low NOx levels. There are 

currently California 1984 certification level data available 

for some but not all of the nationally certified engine 

families and an evaluation of the accuracv of the estimated 

values may be made on an engine family basis. [l] The 

estimation overestimated the particulate standard levels at low 
Manufacturer 

General Motors 

Volkswagon 

Nissan 

Merce,des-Benz 

Isuzu 

Audi 

Peugeot 

Volvo 

Sales-Weighted 

Industry Wide 

Average 

10-4 

Table 10-1 

Relaxed Scenario 

Corporate Average Particulate 

Standard Levels for LDDVs 

(grams per mile) 

1.0 g/mi 1.5 g.mi 

NOx Standard NOx Standard 

.so .29 

.21 .20 

.29 .26 

.60 .42 

.22 .20 

.26 .20 

.36 .26 

.41 .29 

.42 .27 

2.0 g/mi 

NOx Standard 

.• 2 5 

.20 

.25 

.34 

.20 

.18 

.21 

.24 

.24 
Manufacturer 

Small LOOTS: 

Ford 

Isuzu 

Nissan 

Mitsubishi 

Toyota 

volkswaqon 

Toyo Kogyo 

Full-Size LOOTS: 

General Motors 

Sales-Weighted, 

Industry-Wide 

Average 

10-5 

Table 10-2 

Relaxed Scenario 

Corporate Average Particulate 

Standard Levels for LOOTS 

(grams per mile) 

1.2 g/mi 1.7 g/mi 2.3 g/mi 

NOx Standard Nox Standard 'Nox Standard 

.30 

.33 

.37 

.43 

.20 

.32 

.30 

.56 

.52 

.29 

.25 

.35 

.39 

.19 

.31 

.29 

.34 

.33 

.29 

.25 

.35 

.39 

.19 

.31 

.29 

.28 

.28 
10-6 

NOx standards for both LDDVs and LDOTs for the majority of the 

engine families that were certified under California's 1984 1.0 

g/mi/1.2 q/mi NOx standards, by an average of approximately 15 

percent. Thus, the corporate average particulate standard 

levels for the low NOx standards should be considered as uoper 

limits, as can the resulting number of vehicles projected to 

require traos under this scenario, as discussed in the 

following section. 

B. Percent of Trao-EauiDped Vehicles 

The methodology for calculating the percentage of each ~odel year's LDOVs and LOOTS- to be equipped with trap-oxidizing 

systems was also presented in Chapter 1. Basically, the number 

of vehicle grams per mile (veh-g/mi) of diesel particulate 

allocated to each ma nu factur er under the base scenario (i.e., 

particulate "averaging" standards of 0.20 and_ 0.26 g/mi for 

LDDVs and LDOTs respectively) was determined from 

manufacturer's projected 1985 sales. Then, the number of 

veh-g/mi of d iese 1 particulate that would actually be emitted 

by each engine configuration under NOx standards of 1.5 and 2.3 

g/mi. for LDVs and LDTs, respectively, without traps were 

calculated. Finally, traps were applied to reduce each 

manufacturer's diesel particulate veh-g/mi to the allowable 

level which gave the percentage of each manufacturer's 

production that would need to he equipped with traps. 

Tables 10-3 and · 10-4 show the percentage of each 

manufacturer's LDDV and LOOT production (and that of the 

overall fleet) that would need to be equipped with traps under 

the base and stringent scenarios for the three sets of NOx 

standards. Under a 1. O g/ini LDV NOx standard, the percentage - of the umv fleet_~"!b_ich _ would require traps under the base 

scenario would more than. double from that required under a 1.~ 

g/mi NOx standard. Conversely, a 2. 0 g/mi NOx standard would 

reduce the requirement for traps by almost half. The stringent scenario would require the LDDV fleet to be trap-equipped as 

follows: 1) nearly all under a 1.0 g/mi NOx standard (95 

percent) : 2) 8 2 percent under a 1. 5 g/mi NOx standard: and 3). 

72 percent under a 2 .O g/mi NOx standard. The trap fractions 

for LOOTS follow verv closely those for LODVs. 

As explained in Chapter 1, 100 percent of HODS are 

equipped with traps under the base scenario without averaging. 

With averaging the percentage of traps would drop to about 7() 

percent. r;nder the str inqent scenario, essentially all RODs 

are equipped with traps, with or without averaging. 
10-7 

Table 10-3 

Percentage of LDDVs Requiring Traps Under 

Various NOx and Particulate Standards, ( q/mi) 

Stringent 

Part., 0.08 Base Part., 0.20 . f.o l.s 2.0 l.o 1. 5 2.0 

Manufacturer NOx NOx NOx NOx NOx NOx 

General Motors 100 81 73 61 27 15 

Volkswagen 83 78 67 6 0 0 

Nissan 89 88 75 33 26 23 

Mercedes-Benz 100 96 79 80 SS 45 

Isuzu 82 77 67 9 0 0 

l\udi 84 77 62 28 2 0 

Peugeot 96 87 64 55 30 5 

Volvo 100 93 71 58 34 16 

Sales-Weighted 95 82 72 48 22 14 

Industry-Wide 

Percentage 
10-8 

Table 10-4 

· Percentage of LDDTs Requiring Traps Under 

Various NOx and Particulate Standards, (g/mi) 

Stringent 

Part., 0.10 Base Part., 0.26 

1.2 1.7 2.3 1.2 1. 7 2.3 

Manufacturer NOx NOx NOx NOx NOx NOx 

General Motors 98 85 77 63 26 7 

Volkswaqen 79 78 78 14 15 15 

Nissan 89 87 87 37 32 32 

Isuzu 85 74 74 26 0 0 

Ford 82 80 80 16 12 12 

Mitsubishi 92 89 89 47 40 40 

Toyota 55 55 55 0 0 0 

. Toyo Koqyo 81 80 80 15 11 11 

Sales-Weighted 95·· ··-0 3 . 77 . 56 24 8 

Industry-Wide 

Percentage 
10-9 

c. 199 5 Orban Diesel Part icu late Emissions Under 

Various NOx Standards 

Raving calculated industry-wide particulate standard 

levels and percentaqes of traps required under each scenario, 

the 1995 particulate emission factors for LDOVs and LOOTS can 

be calculaterl. As explained in Chapter 2, the 1995.particulate 

emission factors for LDOVs or LDDTs of a specific model year 

are calculated using the age distribution of the in-use fleet, 

the percentage of that model year's fleet equipped with traps, 

the average non-trap emission level of those vehicles which are 

equipped with traps, the particulate standard, and the annual 

trap-failure rate (i.e., 1.5 percent per year). 

The particulate emission factors for 1961-86 model year 

LDDVs and LOOTS remain the same as those in Chapter 2, due to 

the fact that all regulatory changes are assumed to occur in 

1987. For the relaxed scenario, the emission factors for model 

year 1987-95 are the sales-weighted industry-wide averages 

shown in Tables 10-1 and. 10-2. For the base and stringent 

scenarios, the 1987-95 emissio~ factors are essentialy the same 

for all NOx standards since the presence of a standard 

requiring control sets the emission level regardless of the 

starting point. ~owever, these particulate emission factors 

are slightly different for each NOx standard, because hoth the 

fleet-wide trap fraction and the average non-trap particulate 

emission levels of those vehicles with traps change as the 

applicable NOx standard changes. When a trap-oxidizer system 

fails, the particulate emission level that the vehicle reverts 

to is different under each NOx standard because of · the 

previously described NOx/particulate tradeoff. ~or vehicles 

with properly operating traps, the emission factors are the 

same. 

These 1995 particulate emission factors were combined with 

the vehicle miles traveled (VMT) breakdown by model year and 

the diesel sales fractions (for both best estimate and worst 

case sales) to yield weighted fleet-wide particulate emission 

factors for each set of NOx standards. Again, this methodology 

is fully described in Chapter 2. To obtain 1995 urban diesel 

particulate emissions, the weighted particulate emission 

factors were multiplied by the total 1995 VMT for each vehicle 

class and by the urban fraction of VMT for each vehicle class 

(i.e., 0.594 and 0.488 for LDVs and LDTs, respectively). 

Table 10-5 presents the 1995 urban diesel particulate 

emissions for best estimate and worst case diesel sales under 

the relaxed and base control scenarios and combinations of the 

various NOx standards. Table 10-6 shows the relative 

contribution of each vehicle type to the totals of Table 10-·5. 
Vehicle 

Type 

LT'U/ 

LOOI' 

Total* 

I.roJ 

LOOI' 

Total* 

10-10 

Table 10-5 

1995 Urban Diesel Particulate Emissions 

Under Various ~ Standards (metric tons) 

L~ OOX = 1.0 g/mi !I1.J oox = 1.5 g/mi !I1.J OOX = 1.5 g/mi 

rm oox = 1. 2 SLmi LOI' NJx = 1. 7 a/mi LOI' OOx = 2.3 qlmi Relaxed Base ··Relaxed Base Relaxed Base 

scenario scenario scenario Scenario SCenario scenario 

Best Estimate Diesel Sales 

36,800 19, 7_00 24,1500 19,100 24,600 19,100 

21,800 ll,700 14,100 11,500 12,200 11,500 

. 135,600 12,200· 115,700 71,400 113,800 71,400 

Worst case Diesel Sales 

84,000 43,800 55,300 42,400 55,300 42,400 

33,900 18,·ooo 21,800 . 17 ,600 18,800 17,600 . 

205,900 ro0,ooo 165,100 106,200 162,000 106,100 

... -· - - .. . -. .· -· 

!I1.J OOX = 2. O g/ml rm r-nx =- 2. 3 9Lmi 

Relaxed Base J scenario Scenari 

22,200 19,000 

12,200 11,500 

111,400 71,300 

49,600 42,200 

18,800 17,600 

156,400 105,900 

* Totals include ~ADV ~r and RHDr1J emissions of 9, 400 and 67, 600 (relaxed) , and 4 '30 

and 36,100 (Base) for best estimate sales and 18, 700 and 69,200 (relaxed) and 9,10 · and 37 ,000 (Base) for worst case sales. 'n1ese are ~t shown since they are the s 

regardless of LD\7 and !Dr ?\Ox standards. 
Vehicle 

TvPe 

Ltx:IV 

LOOI' 

MfJJ/IlifN 

HHDV' 

Total* 

u:DJ 

LIDl' 

MIN/IRIN 

H?-10\T 

'!'otal* 

10-11 

Table 10-6 

Relative Contribution of 1995 Urban Diesel 

Particulate Emissions Under Various t-l)x Standards (percent) 

LIJV' t-'()x = 1.0 g/mi UN NOx = 1.5 g/mi rm NOx = l.S g/mi UN NOx = 

wr oox = 1.2 g/mi rm oox = 1.7 q/mi U1l' NOx = 2.3 at::mi rm NOx = 

Relaxed Base Relaxed Base Relaxed Base Relaxed 

Scenario Scenario Scenario Scenario Scenario Scenario Scenario 

Best Estimate Diesel Sales 

27 27 21 27 21 27 20 

16 16 12 16 11 16 11· 

7 7 8 6 8 6 8 

so so 59 51 60 Sl 61 

100' 100 100 100 100 100 100 

Worst case Diesel Sales 

40 40 33 40 34 40 31 

16 17 13 16 12 16 12 

10 9 12 9 11 9 -.12 -- -

34 34 42 35 43 35 45 

100 100 100 100 100 100 100 .. ;....:·.; •• - ........ - ··---~;._~~-~ .... ,, •. ~: • ·'.lO. .. , - . " .. ·or-•··· r ... ~ -4-·· .. ·- ............ .,,. ~-- : ... -; . -·-·- ,; . .. r' ;~. ' ~-~ ~ ... -.·.- -. . - . 

2.0 g/mi 

2.3 gl!!!i Base 

Scenario 

26 

16 

7 

51 

100 

40 

16 

9 

35 

100 

·- .... ,....,_~ ~- ... . .... >-- . ' . . - .. -.-:: / · .. ~: ... · < -- _f-·I •• ' .-., r _,.. I .< 
10-12 

The results shown in Table 10-5 indicate that 1995 urban 

diesel particulate emissions under the relaxed scenario do not 

change substantially from those evaluated in Chapter 2 (i.e. , 1.5/2.3 g/mi NOx standards) except for the most stringent 

1. 0/1. 2 q/mi NOx standards. For the 1. 0 g/mi Ncix standard, 

LDDV emissions increase by 50 perc~nt as compared to a 1.5 g/mi 

NOx standard. For the 1. 2 g/mi NOx standard, LOOT - emissions 

increase by 79 percent as compared to a 2.3 g/mi NOx standard. 

Total 1995 urban diesel particulate emissions increase hy 19 

oercent under the 1.0/1.2 g/mi set of NOx standards as compared 

:o the 1.5/2.3 g/mi_~~~~ 

Under the base scenario, the changes with NOx standards 

are less significant. The 1995 LDDV urban diesel particulate 

emissions increase only 3 percent under a 1.0 g/mi NOx standard 

as compared to a 1.5 g/mi NOx standard. For the other changes 

in the LDDV and LOOT NOx standards, the situation is similar, 

with very little change in emissions occurrinq. 

The results of Table 10-6 are similar to Table 10-5 in 

that the only NOx standards causing strong difference fro~ the 

main analysis are the 1.0/1.2 g/mi NOx standards under the 

relaxed scenario. The contribution of LODVs and· LODTs under 

best sales estimate to total 1995 urban diesel particulate 

emissions increases from 21 to 27 percent, and from 11 to 16 

percent, resoectively, under the more stringent set of NOx 

standards. The other vehicle types (i.e., MDV/LHDV and HHOV) 

decrease their relative contribution with HHDV's share 

decreasing the most (from 60 to 50 percent). The results are 

----similar for the- worst case diesel sal-es situation • 

• ~. . ;· ·~ ... -·." J- -- •.· . ·." ·• ... • ·- • . •<j'. • • . ·-

Uhde.r _the ~:.stringent scenario, there·-·is .,little difference 

among Nox· standards (see Table 10-7). Overall, the breakdown 

under the stringent scenario is between that under the relaxed 

and base scenarios. 

The decrease in urban emissions obtained under the 

stringent scenario versus the relaxed scenario is between 5'6 

and 72 percent for all vehicle types with the total decrease 

being 65 percent. Compared to the base scenario, the stringent 

scenario reduces total emissions by 4 3-4 6 percent, with the 

change in each vehicle class being 37-54 percent. 

Table 10-8 compares urban emissions under the three 

control scenarios coupled with NOx standards of 1.0/1.2 g/mi to 

previous diesel particulate studies. .~s can be seen, 

projections for the base scenario are virtually the same as 

that projected in lq79-80 for the same standards (controlled 

scenario). Fowever, even under the stringent NOx standards, 

emissions under the current relaxed scenario are well below the 

uncontrolled levels projected in previous analyses. 
10-13 

Table 10-7 

1995 Urban Diesel Particulate Emissions Under 

the Stringent Scenario (metric tons) 

l.0/1.2 

Vehicle Tvoe g/mi ~ 

LW/S 10,700 

UX7l'S 5,900 

MIX1J /[ROOJs 2,700 

HRDOV'S 22,600 

Total 41,900 

IDI:1J'S 22,500 

LIDl's 8,900 

fv1DOV' /IROOVS 5,000 

HliDOt/S 23,100 

Total 59,500 

l.5/1.7 

g/mi ~ 

2.0/2.3 Relative Con- · Reduction From 

g/mi ~ tribution (%) Base (%) 

Best Estimate Diesel Sales 

10,000 9,500 

5,600 5,400 

2,700 2,700 

22,600 22,600 

40,900 40 ;;200 -

Vk>rst case Diesel sales 

20,900 19,700 

8,500 8,100 

5,000 5,000 

23, 100 23, 100 

57,500 55,900 

24 

13 

7 

56 

100 

36 

14 

9 

41 

100 

48 

53 

44 

38 

43 

51 

54 

46 

37 

46 
i ~ •• 

10-14 

Table 10-8 

Comparison of Current Urban Emission Estimates 

Under Various NOx Standards* to Urban Emission 

Estimates of Previous Studies 

Scenario 

1995 Urban Emissions Under LDV 

ind LDT NOx Standards 6f·l.b 

and 1.2 g/mi (metric tons) 

Best Estimate Diesel Sales 

·· 19 7"9 .:.so· Uncon t·rollea--

Relaxed 

Base 

1979-80 Controlled 

Stringent 

1979-80 Uncontrolled 

Relaxed 

Base 

1979-80 Controlled 

Stringent 

Worst Case Diesel Sales 

-- :~·· ·- 239,000 

137,000 

72,900 

71,000 

42,300 

287,000 

207,300 

108,600 

85,000 

59,900 

* The NOx standard scenarios of LDV = 1.5/LDT = 1.7, and LDV 

= 2. O/LDT = 2. 3 g/mi are not shown because all "relative 

-reductions" are less- than ·-4·--pe·rcentage ·points differ·entthan tha 1.5/2.3 g/mi case, .•• ·~.~--·~"':~' • - ., •. --·-.- .... ___ .-._ ..... ~~1.1: -··· _ ..... · -:-'...•:tl" ~;-~·._ .• .1..: 

.... -·· ~' . 
10-15 

o. Cost Effectiveness 

The cost effectiveness for LOOs and HODs under 

scenario was already determined in Chapter 9. Tables 

and 9-3 of that chapter show the development cost-effectiveness values. 

the base 

9-1, 9-2, 

of those 

In this study, cost effectiveness is the annualized cost 

per vehicle divided by the annual emission reduction per 

vehicle, both relative ·to the relaxed scenario and on a 

fleet-average basis. The fleet-average annualized cost is a 

straight-forward annualization of the fleet-average lifetime 

costs using a 10 percent discount rate. The fleet-averaqe. lifetime cos.ts are a function of - the lifetime costs of 

trap-equipped vehicles of various sizes, the trap-equipped 

fraction of each vehicle size category, and the relative sales 

of each vehicle size category. The lifetime trap-oxidizer 

system costs for different size vehicles and the relative sales 

of these vehicle sizes we~e described in Chapter 8. The 

trap-equipped fractions of the LOOV and LOOT fleets under 

various· NOx standards were estimated in Section IIB of this 

chapter.* 

The 

explained 

reduction 

vehicle's 

scenario) 

effect of 

rate. 

determination of annual emission reductions was 

in. Chapter 2. Basically, . the annual emission 

per ·vehicle is approximately the reduction in the 

emission rate at hal-f-life (compared to the relaxed 

multiplied bv the lifetime-average annual VMT. The 

trap failures is included in the· vehicular emission 

Table lo--9 compares the -cost· effectiveness of the various , .... ".,LOO _. oa.r_t;i,c~uJ.a t.e .... con.trol . sc_ena.r,ios .. ,. unde·.r:.· ••-:··d iffer-.en-t · · · · N.0x- · ... . :.:..·~·-. .--~ 

· .;~ ·Stand~rds ~- · 't'a:b'le·.~ to-10 '-compares the cost e ff ec-t ive·n1ess ·· o·f t'h~ f'\("l.H'("l-:,'-: 

various HOD particulate control scenarios. These tables 

include the fleet-average annualized cost per vehicle, the 

annual emission reductions per vehicle, and the urban cost 

effectiveness (as described in Chapter 9). Table 10-9 also 

shows the trap-equipped fraction for Loos (assumed to be 100 

percent for HDDs, except where averaginq is applicabl~ the 

fraction is reduced to 70 percent). 

* It is assumed in this analysis that f.or· LDOVs, large 

vehicles are first equipped with traps, followed by medium 

vehicles, and then small vehicles until the trap-equipped 

fraction is met. Similarly, for LOOTs, full-sized LDDTs 

are first equipped with traps, and then small LDOTs, until 

the trap-equipped fraction is met. 
Table 10-9 ~ ~ 

~ <· . 

UXJJ and LDUl' Cost-Effectiveness Values lbder Various 

Particulate Control Scenarios and NOK Standards ($/metric too) 

···!:: 

Base Scenario ~· ; 

Stringent Scenario;; 

NO><=l.O/ N:>x=l.5/ 

1.2 g/mi 1.7 g/mi 

cent Vehicles F;quipped with Traps 

DCNs 

oors 

48% 

56% 

22% 

24\ 

et Average Annualized Cost Per Vehicle* 

DD/s 

oors 

$18.85 

$20.77 

$9.19 

$8.83 

i: "00x=2 • 0/ 

".-.. 2. 3 g/mi 

'. 14% 

'~ 8% 

.·.;.. 

·'Ji 

., 

~ • l 

$5.73 

$2.81 

ual flnission Reduction Per Vehicle (metrib~tons)** ' . 

OOx=l.O/ OOx=l.5/ .00x=2.0/ 

1.2 q/mi 1.7 g/mi ·2.J g/mi 

95% 

95% 

$35.27 

$34.56 

82% 

83% 

$30.79 

$31.24 

72% 

77% 

;; $27 .85 

' $28.34 

ocws 

IDl's 

2.01 x lo-3 

2.65 x lo-3 

6.60 x lo-4 '3.90 x lo-4 3.15 x lo-3 1. 11 x lo-3 

1.00 x lo-4 ;'i 10 x lo-4 4.lo x lo-3 2.20 x lo-3 

l.54 x '10-3 

i. 11 x lo-3 i 

t Effectiveness ($/metric ton) 

IDJS 

OOl's 

$9,100 

$7,800 

$13,900 

$12,600 

an Cost Effectiveness ($/rretric ton) 

; ;, $14, 700 

:': $13 ,400 : ~ ~- ; .. ' 

$11,200 

$8,400 

$17,400 

$14,200 

:i $18,100 

: $16,000 

.. " 

d 

. ! ii '. 

[)(}J5 $15 I 400 $23 I 400 $24 I 700 ! $18 I 900 $29 I 300 i $30 I 800 

IDl's $16,100 $25,800 $27,400. $17,300 $29,100 :;$32,800 

Based on estimated sales fractions off 29, 37, and '32 percent for large, med0il.UD, and' 

small LOOJs, respectively; trap-oxidiz~r systems fitted to these vehicles!' have ·an 

average lifetime cost of $219, $234, aaj:$266, respectively. Small and full-si~ed LOOI's 

are estimated at 34 and 66 percent o~ 'sales respectively, with trap-oxidizer's system · 

lifetime costs of $229 and $252, respec~ively. . ·- · 

-Based on estimated annualized travel. ofi 10,000 miles and 10,900 miles for LOOJs and 

UDI's, respectively; reductions are c~red to relaxed scenario. · ~· r. 

.._. 

0 

I 

.._. 

0\ 

I I 
10-17 

Table 10-10 

HOD Cost-Effectiveness Values 

Under Various Control Scenarios ($/metric ton) 

Base Scenario Stringent Scenario 

Fleet-Average Annualized Cost Per Vehicle* 

MDVs 

LHDVs 

HHDVs 

$ 84 

$132 

$228 

·$ 84 

$132 

$228 

Annual Emission Reduction Per Vehicle (metric tons)** 

MDVs 

LHDVs 

HHDVs 

0. 00_60 

o. o 171 

0.0560 

Cost Effectiveness ($/metric ton) 

MDVs 

LHDVs 

HHDVs 

$14,000 

$ 7,700 

$ 4,100 

0.0086 

0.0246 

0.0799 

$9,800 

$5,400 

$2,800 

·Cost Effectiveness, With Averaging ($/metric ton)*** 

MDVs 

LHDVs . .. ·-. :·HHDVs 

$9,800 

$5,400 

$2,800 

Urban Cbst Effectiveness, With Averaging ($/metric ton) 

,!;.,,-,,-:-.;. 

MDVs 

LHDVs 

$20,000 

$11,000. 

• -1 • ... ~ .,;;; ~ ' .. ; ,,._ •• 

$20,000 

·s11,ooo 

·Sl-1-, .Q O O 

* Assumes all HDDVs are equipped with traps, unless 

averaging is used. Trap-oxidizer systems for MDVs, LHDVs, 

and HHDVs have an average lifetime cost of $472, $425, and 

$1,516, respectively. 

** Based on estimated annualized travel of 13,750, 23,300, 

and 50,100 miles for MDVs, LHDVs, and HHDVs, respectively: 

reductions are compared to relaxed scenario. 

*** Averaging affects the base scenario only: average 

fleetwide costs are estimated to decrease by 30 percent 

(i.e., 70 percent of HDDs equipped with traps). 
-::.."'" t <t ... 

10-18 

Table' 10-9 shows that under a qiven set of standards, 

cost-effectiveness of LDDT control ranges between $1000-3000 

per metric ton le~s than that for LDOVs, meaning that LDDT 

control is slightly more cost effective. More importantly, the 

table also shows that a qiven particulate scenario becomes less 

cost effective with higher NOx standards. For example, control 

·is noticEH1bly less· cost effective when the NOx ·s'Ea-ndards change 

from 1. 0/1. 2 g/mi to 1. 5/1. 7 g/mi. This is due to the fact 

-that stringent NOx controls raise enqine-out particulate levels 

and increase the degree of control provided by adding a trap. 

~ -=· --- .·:: .. -.unde:r..:: a.: g-i-ven~--NOx- s-t-an·a·a·rd,-=- 7-=-the str-inaent ·scenario: ts· 

moderately less cost e·f feet ive than the base scenario. The 

difference, which ranges between 7 and 27 percent, is to be 

expected, since the additional traps being applied under the 

stringent scenario are being applied to vehicles with lower 

engine-out particulate levels, thus providing less control. 

Trap costs, on the other hand; are relatively constant. 

For heavy-duty diesels (Table 10-10), cost effectiveness 

imoroves from the liqhter to the heavier vehicles. While the 

emission reductions for the various HOO classes are the same on 

. a percentage bas is, they are greater for the heavier vehicles 

on an absolute basis (due to greater absolute emission rates 

and qreater annual VMT). These effects more than compensate 

for the increase in trap cost with vehicle size and the lower - .... --urban-V-MT--~r-action o-f-Class ·VII-VIII fiDDs. 

Without averaging, the base scenario for fiDDs is less cost 

effective than the stringent scenario. Without averaging, the 

base scenario, like the string_~nt scenario, requires all HDDs 

"t'o: ·be"· ·e~qu fp?e'C'.L wU:h ·: f'rap?f: .""!t 'waf · a··ssufoe(f' 'fffa't:~ ''fraps' ·und'e"'r "'t'.ife ::_''.--'"\ 

base .. scenario would only be- as -- e-f f ic-ien t as needed, - but would 

cost the same as traps under the stringent scenario. Thus, the 

costs of both scenarios are the same, but the emission 

reduction under the base scenario is less. Thus, the higher 

cost-effectiveness value of the bas~ scenario. 

With averaging, the cost effectiveness of the base and 

stringent scenarios becomes the same. This is to be expected. 

Trap costs and efficiency under the two scenarios are assumed 

to be the same. The only difference b~tween the two scenarios 

is that only 70 percent of all RDDs are equipped with traps 

under the base scenario, while all RDDs are trap-equipped under 

the str inqent scenario. However, this difference affects both 

costs and · emission reductions. Thus, cost effectiveness 

remains constant. 

In qeneral, particulate control for ~Dos is 

effective than that for LDDs when compared under 

scenario. 

more 

the 

cost 

same 
10-19 

III. The Intermediate Control Option 

Between the relaxed scenario (no control aside from that 

already applied) and the base scenario (some traps required as 

a control method) there is a third scenario: the intermediate 

control option. In this option a modest degree of control may be obtained via predominantly non-trap technqlogy. For 

example, electronic fuel injection and sophisticated electronic 

exhaust gas recirculation (EGR) systems {to reduce the negative 

impact of stringent NOx standards) appear to be available and 

able to provide some control. There is also the possibility that certain high-emitting engine lines may be dropped in this 

timef rame due to fuel economy and other pressures. Finally, 

there is some indication that . oxidation catalyst technology 

·co·upled wtth s·ohist::lcated · throttle control can be applied to 

some diesels to substantially reduce particle-bound organics. 

The effect these non-trap control techniques could have in 

reducing the current corporate average particulate standard 

levels, at both the 1.0/l.2 g/mi and 1.5/l.7 g/mi NOx standard 

levels, will be discussed in _this section. 

It· appears almost certain that GM will drop their 

5.7-liter engine by 1987 of their own accord. (GM has already . dropped this engine from its 1984 California model line and has 

indicated the engine will be eliminated from the Federal market 

in 1986.) Assuming that the presently equipped 5.7-liter 

engine vehicle will receive GM's 4.3-liter engine, GM's average 

particulate standard would drop from 0.29 g/mi to 0.16 g/mi at 

the l. 5 g/mi NOx standard and from 0. SO g/mi to 0. 34 g/mi at 

the l.O g/mi NOx standard. These rarge reductions in GM's 

corporate average emission levels under both NOx levels would 

result in substantial reductions to the total LDDV particulate · emis·sions, due ·to GM' s large share {60 percent) of the tota1 · · . LDDV ... estimated sales. T.he sa,les-we ighted-. industry-wide ·average· - ·· ·· ·' · , ... ,_. ~pa·r·t·:i.cula·t:·e: ·· s-tanda·rd"'· levels·; · ·as~ .. : !is ted in '""·Tab"te · 10 • i;.: wou-::l."'d-;:· c:·;:.r.'i:J.J .:.• ;; 

change from 0.27 g/mi to 0.20 g/mi at the 1.5 g/mi NOx standard 

and from 0.42 g/mi to 0.32 g/mi at the more stringent 1.0 g/mi 

NOx standard, a 25 and 24 percent reduction, respectively. 

Engine-out control techniques include EGR systems and 

electronic fuel injection. Sophisticated EGR systems are 

available and already being applied on a few 1984 vehicles in 

California to comply with its 1.0 g/mi NOX·. standard. These 

systems should be able to reduce the particulate penalty 

associated with the stringent NOx standard by one-half. While 

the effect of · electronic injection is uncertain, it should 

provide a benefit for the highest emitting engines; at least 

improving the NOx/particulate trade-off. 
10-20 

Some data on catalyst technology coupled with intake-air 

throttling shows that it can remove most of the organics 

associated with the particulate, which represent 10-20 percent 

of total particulate mass. Since particulate is not 

permanently stored by these catalysts, no reqeneration is 

needed and the· practical problems associ~ted with 

trap-oxidizers are ·avoided. However, one remaining _question 

with this technology is sulfate production. Also, it is not 

certain whether catalysts would be effective on all LDD 

models. At least one manufacturer (Volkswagen), which only 

requires a small emission reduction to meet the current 1985 

standards and should be interested .in catalysts, appears·-to-be 

concentratinq all of its efforts on traps. Thus, this- analysis 

will not presume the availability of catalysts under this 

option. 

The identification of standards actually achievable with 

these techniques requires a manufacturer by manufacturer 

analysis, due to their different starting po in ts and the fact 

that some of these reductions are only applicable to certain 

manufacturers. Also, the two NOx standards ( 1. 0 and 1. 5 g/mi 

for LDOVs and 1. 2 and 1. 7 g/mi for LOOTS) must be discussed 

separately due to the ·differences in the control techniques' 

effects on particulate emissions at these different NOx levels. 

Beginning with LODVs at the more stringent NOx standard 

ann GM, the aoplication of sophisticated EGR systems and the 

discontinuation of their 5.7-liter enqine line would reduce 

their average emission level to roughly 0.23 g/mi. Use of 

electronic fuel injection could reduce this level further. 

'"·"· Mercedes-~enz, on the -other hand, ~ppear s to.-· b.e in a~ very · '' 

different position. Sin6e it · h~s n6t projected the 

niscontinuation of any of its engine lines, nor has there been 

any indication that simple changes in basic engine design are 

forthcoming, emissions of its 3.0-liter engine will not be in 

line with those of the other manufacturers, though its new 

2.2-liter engine has relatively low emissions. Mercedes-Benz. 

has actually indicated to California that, in 1985, they plan 

to equip their 3.0-liter engines with traps to meet the 0.4 

g/mi California particulate standard coupled with the 1.0 g/mi 

NOx standard. Improved EGR systems should be able to reduce 

their corporate average from 0. 60 g/mi to at best 0. 40 g/mi. 

Electronic injection could further reduce this figure, but 

probably not below 0.35 q/mi. At the same time, Mercedes-Benz' 

trap development program appears to be more advanced than those 

of the other manufacturers and they appear ready to implement 

traps in 1985. Also, one cannot rule out the llSe of major 

engine modifications to bring its 3.0-liter engine emissions in 

line with those of other manufacturers. Overall, it appears 

most likely that Mercedes-Benz would probably require traps at 

or below 0.40 g/mi, but will also be in good position to do ... "" ~ C1 
ln-21 

Concern inq the other Lonv manufacturers, imoroved F.(';'!:1 

svstems alone should reduce their averaqe emission level to 

O.Jn a/mi or below, except possibly for Peugeot, due to a 

sinale hiah-emitting vehicle configuration. Electronic fuel 

iniection and other enaine modifications mav he ahle to reduce 

these levels to 0.25 a/mi. 

Overall, these techniaues could reduce oarticulate 

emissions rouahlv 10-40 oercent from the relaxed scenario's 

0.42 a/mi sales-weiahted industrv-wide averaae value at a 1.1') 

a/mi NOx standard. Thus, an !.DOV standard ranqe of o. 25 to 

0. 30 q/m i should he achievable without marw tr aos, exceot for 

Mercedes-Benz. Tn the case of ~ercedes-Senz, it does not 

aooear reasonahle to limit the ~chievable emission standard to 

O. 40 a/mi or even h iaher based on a s inc:rle manufacturer or 

vehicles no laraer or smaller than other manufacturers. 'T'hev 

and possiblv others would simoly have to aooly traos to a 

limited number of vehicles in order to ohtain the final dearee 

of control. 

~t the hiaher NOx standard level of 1.5 a/mi for LDDVs, 

the enqine improvements just a iscussed will not have as larae 

an -effect on particulate emissions as just seen at the more 

strinaent NOx standara. ~he particulate/NOx tradeoff, as 

discusserl in the tech~oloav chaoter, lev~ls out as the ~ox 

level increases from the 1.5 q/mi NOx standard level. ~he 

oarticulate emission renuction due to. enaine improvements 

cnmbined with the discontinuation of the ~M ~.7-liter enaine 

would result iri an ov~rall r.ODV standarn of aooroximatelv 

n.1s-n.20 a/mi. At this level some traps will be necessarv for 

the hiaher-emittina enaines of Mercedes Benz and Peuaeot ~lthouah not to the extent needed at the l.O a/mi NOx standard • 

. c.·-·.·-.,.·~···-,r;he···-aooJ.ic-a't"ion. of tne's'e. non-trao co.ntrol · technl.ques .. ··to'···-·-::: .. 

T,DD'rs also reduces their averaae oar t icula te emission levels 

from those sho•¥T"! in "'ah le 10-2, althouah to a far les~ extent 

than the Lnnv emission reduction. Unlike Lnnvs, there are no 

discontinuations oroiecterl for anv of t~e hiaher-emittina 

enaine lines. 'T'hese tec~niaues could re~uce the sales-weiqhted 

innustrv-wide averaae valuP.s from O. c:;? a/mi to Aooroximately 

0.35 a/mi and from 0.33 a/mi to aPProximately n.30 a/mi, for 

NOx standards of 1.2 ana 1.7 a/mi, resoectivelv. 

'T'he sales-weiahted industry-wide oarticulate levels under 

the inter~eniate control option are s~own in ~ahle in-11. "'his 

table includes both LOOVs and LOOTS coroorate averaae 

oarticulate stanrard levels at the two NOx standards. ~or the 

LOOVs, the hiaher value of the standard ranae was iricluded, as 

a conservative proiectinn. 'T'he percentaae of vehicles 

requirina tra;>s is also shown in rrable 10-11. Aoplvinq the 
10-22 

Table 10-11 

The Effects of Advanced Control 

Technoloav Improvements on the Sales-Weiqhted 

Industrv-Wlde Averaae Particulate Standard Levels 

LDDV LOOT 

Scenario 

1.o 

NOx Std 

1.5 

NOx Std 

l.2 

NOx Std 

l. 7 

NOx Std 

Intermediate 

Standard Level, · - ·-'- ·-- g/mi. 

Base 

Percentaqe of 

Vehicles 

Requirina Traos 

Standard Level, 

c;r/mi 

Percentage of 

Vehicles 

Requiring Traps 

.,.. . ...... . '" .~~.,·· 

0.30 

1-2 

0.20 

10-20 

0.10.;;o.20 0.35 0.30 

1-2 9-lf; 0 

0.20 0.26 0.26 

1-2 41 ln 

. .:.·. ~.· .. ~~ · .. 
10-1'3 

advanced control technologies descri~ed above and also 

includinq· the effects of dropping the r,M 5. 7-L enaine will 

reauire aporoximatelv one to two percent of r.oov enqines to he 

equipped with traps under the intermediate scenario for both a 

1.0 ann l.~ a/mi NOx standard. ("T'he more strinaent NOx 

standard will reauire aooroximatelv an eaual amount of traps as 

the less strinaent l.~ ~Ox standarn nue to it~ hiaher corporate 

averaqe oarticulate standard level under the intermediate 

scenario.) ~oolvina the advanced control technoloa ies to LDD~ 

results in 9-1~ percent of the LDO~s at the 1.2 a/mi NOx 

standard reau1r1nq traps: at the 1.7 a/mi NOx standara, no 

traps are necessarv. 

'rn adaition to usina onlv traps as a control method under 

the hase scenario, it is of interest to project the PercentaaP. 

of vehicles reau1r1na traps if the anvanced control 

technoloaies of the intermeniate scenario are also apolied 

under this 0.20/0.26 a/mi tnnv/t~n~ oarticulate standard 

scenario. ~en to 20 oercent of the Lnnvs will he equipoed with 

traps ~nder the 1.0 a/mi Nnx standard, while one to two percent 

will reau ire traps under the · 1. 5 q/mi NOx standard. It has 

also heen assumen that thE'! 5. 7-T, enaine will be nroooed from 

the GM enqine line. With the advanced control technoloqy 

imorovements aoplied to T.OOTs, 45 percent of the full-size 

LOO"T's and 31 percent of the small LOOTS will require traos at 

the l.2 a/mi NOx standard. {Fortv-one o~rcent of all L!10"T's 

will require traos.) ~t the 1.7 a/mi NOx standard, 18 percent 

of the s1"al l r.OOTs ann 11 Percent of the small t.rmrrs will be 

trao-eauipoe'1. (~ixteen percent of all LDD"T's will be 

tr ap-eau i Ppea.) 'T'hese oercen taaes of vehicles reau ir ina tr aos 

under the hase scenario are shown in ~able 10-11. 

T.V. . ro1T1oa r . .i so!"I C'l.f. ,T,lncon trolled anc.i .. J".ori t ro 1-1.e.cl unn Fmis.sicn s 

TTrhan diesel oarticulate emission~ from ~nos wen:. 

estimated for the rP.laxed control scenario in Chapter /.. 

uowP.vP.r, the corresoondina valu~s f.or a completelv uncontrollea 

μDD fleet were never derived in that chaoter because such a 

strateqv is not consineren to he a viable ootion. 

Nevertheless, it is of interest to know what future urban ~oov 

emissions would be if'. the fleet were · totallv uncontrolled so 

that the henefits of the relaxea control scenario in oarticular 

can he olaced in oP.rsoective. 

l\s indicatea in r.haoter 1, uncontrolJ.ea i.ioovs are 

estimated to emit particulate at a rate of 0.7 q/B?~-hr 

throuahout their lifetime. Usina the methodoloav of Chapter 3, 

the resulting vehicular em i ~s ion factors a re shown in rrable 

10-1/.. 't'able ].''-11 oresents the J9q5 urhan oarticulate 

emissions for the various HDDV scenarios using hest estimate 
10-24 

Table 10-12 

Uncontrolled HDDV Emission Factors By Model Year (q/mi) 

MDV LHDV HHDV 

Model Year Class iIB Classes III-V Class VI Classes VII-VIII 

1995 0.930 1. 212 1.611 2.489 

1994 0.930 1.216 1.611 2.492 

1993 0.930 1. 221 1.611 2.497 

1992 0.930 1.221 1.611 2.501 

1991 0.930 1.221 1.611 2.506 

.. . . -- - .. ·~· ··-· . 1,9-90 0.930 1. 234 1. •. 6_11 2.-50-9 .. - -· 1989 . - 0. 93"6 -1. 23_5_ 1. 612 2.514 

1988 0.943 1. 235 1.612 2.519 

1987 0.951 1.239 1.614 2.530 

1986 0.967 1.239 1. 614 2.531 

1985 0.968 1.243 1.614 2.550 

1984 0.977 1.247 1.617 2.558 

1983 0.993 1. 24 7 1.620 2.561 

1982 1.002 1. 247 l. 628 2.577 

1981 1.003 1. 252 1.651 2.587 

1961-80 1.014 l.256 l. 651 2.597 
10-25 

Table 10-13 

HDDV Urban Emissions in l9t5 

Best Sales Estimates (metric tons oer year) 

Uncontrolled Relaxed Base Stringent 

88,000 77,000 40,800 25,300 
10-215 

sales o·roiections. Relative to t!1e uncontrolled scenario, the 

relaxed scenario would reduce particulate emissions ahout 12 

percent, the base scenario about ~4 percent, and the strinaent 

scenario about 71 percent. 

v. 1='.ffect of C"h·anaes· in Diesel ~ales Proiection~ on Prhan 

Particulate Levels 

,,..hrouahout this report, ~iesel partii:ulate emissions were 

evaluated usina ~PA's best an~ worst diesel sales Proiections. 

The ~hest ~ase" Pro1ectiori is hase~ on a rever~al of verv 

recent conn it ions (where Lnn·v sales have beP.n decreas inq) and 

shows moder~te growth in sale~. 'T'he "worst case" proiecti on 

reoresents a s ianif icant (or maximum) arowth in diesel sales 

that could result from another oil crisis. 'T'herefore, the 

worst case is an upoer bound on future diesel sales. Of 

course, it is also oos~ihle that the demand For aiesel-fuelea 

veliicles will not continue to_ increase if Petroleum supplies 

re~ain abun~ant and the fuel orice does not escalate. rn order 

to indicate the erfect on diesel oarticulate of this latter 

sales Pro~ection, ~ "no arowth case" will he evaJuated. 

i:n constructinq the no arowth diesel orojection, Lnov and 

tnD'l'.' historical ciesel and total sales frn~tions were used for 

model years l91i9-R1. ~uture model year diesel sales fractions 

were then found bv simolv continuina the 1QR'3 model vear values 

throuah the 19Q5 model vear. For RDDVs, historical data were 

similarly used for moael vears lQfiQ-82. 'T'he 198'3 model VP.ar 

sales Fraction was determined from orojections made bv Eneray 

and tnvironJT1ental Analysis, Tiic. (21 and were extraoolate~ 

throucHi'·· .. t:he ··199·5· mocleT- vear." TR .. e· '"re~foltina ... 'no· a-row.th'"· sate·-s·::. .. _::-'.'- ''or·oiection ls shown in' rriahle 10-14. ,_ ............ - . . .. .,, '• .... . 

niesel Particulate emissions under the no growth case for 

anv calendar vear can now be calculated bv comhinina the 

respective diesel sales fractions · with the other inouts as 

~~scrihed in rhapter 2. To illustrate the erfect of usina this 

alternative arowth oroiection, Table 10-15 contains a 

comoarison of urhan diesel particulate emissions for the hase 

scenario unCler this sales estimate to those associated with the 

he5t estimate oroiection. a.s shown, in the 1Cl9c; calendar vear, 

the overall effects of no arowth in diesel sales is a 1~ 

percent rerluction in proiecteil emission J eve ls assoc iateCl with 

the best est ifTla te. Ind iv iduall v, the la raes t cha nae is shown 

for tnnrrs (i.e., a 71 oercent reduction), while the smallest 

chrtnae is shown for 1-l~DVs (i.e., a 13 oercent reduction). 'T'he 

Percent chanae within eac~ vehicle cateaorv shown here for the 

hase scenario also will be similar for the other control 

scenarios if the rio a rowth sales pro i ect ion was use a in place 

of the best sales estimate. 
10-27 

Table 10-14 

Diesel Fraction of Total Sales 

for LDDs and HDDVs--No Growth Estimate 

Model Class Classes Classes 

Year !&QY L.ODT ·- IIB III-V Class VI VII-VIII 

1995 .030 .060 .162 .162 .377 .810 

1994 .030 . .060 .162 ·.162 .377 • 810 

1993 .030 .060 .162 .162 .377 • 810 

1992 .030 .060 .162 .162 .377 • 810 

1991 .030 .060 .162 .162 .377 .810 

1990 .030 .060 .162 .162 .377 • 810 

1989 .030 .060 .162 .162 .377 .810 

1988 .030 .060 .162 .162 .377 • 810 

1987 .030 .060 .162 .162 .377 .810 

1986 .030 .060 .162 .162 .377 • 810 

1985 .030 .060 .162 .162 .377 .810 

1984 .030 .060 .162 .162 .377 • 810 

1983 .030 .060 .• 162 .162 .377 .180 

1982 .040 .070 .074 .108 .214 .928 

i98l .061 .060 .637 .054 .164 • 918 

1980 .034 .034 .ooo .ooo .114 • 910 

1979 .028 .028 .ooo .ooo .114 .890 

1978 .009 .009 .ooo .ooo .078 .880 

1977 .004 .005 .ooo .ooo .070 .850 

1976 .003 .003 .ooo .ooo .042 .830 

1975 .003 .002 .ooo .004 .032 .730 

1974 .003 .000 .ooo .001 .016 .770 

1973 .003 .ooo .000 .003 .016 .780 

1972 .003 .000 .ooo .020 • 016 .760 

1971 .003 .000 .ooo .• 020 • 016 .750 

1970 .ooo .ooo .ooo • 020 • 016 .750 .. . . -·.. - 19 6 9 -·· \. . ·:· .·o o o · ·· ·::: · :-:·o oo· · . · _ =··o·o o· .· . ,_ . .... 000 :ao·o· ·· · ·· ~- ts·o ~ ~·l;··- ~., · ~- .. -la te·r· ·· -·" · ··· -·- ·· l;. -,. - - .. l. 

· -- and 
LDOV 

LOOT 

MDDV/LHDDV 

HHDDV 

TOTAL 

10-28 

Table 10-15 

1995 Urban Diesel Particulate Emissions 

Under the Base Scenario (metric tons)* 

Best Estimate 

Diesel Sales 

19,700 

ll,700 

4,800 

36,100 

72,200 

No Growth 

Diesel Sales 

10,100 

3,400 

2,700 

30,300 

46,500 

% Reduction 

f C'Om 

Best Estimate· 

49 

71 

44 

13 

36 

,,. ••.• ·-... ., •. j, • •• :: 

., v·· ·•· .... ;.::.... ···: r·. 

·* Assumes .. an LDDV NOx standard of l. 0. g/mi . and an LO.OT .. NOx 

standard of 1.2 g/mi. 
APPENDIX 
Table A-1 

Estimates of the Potency of Organic Extracts of Diesel 

Exhaust and Related Environmental Emissions - Harris* 

Emissions Extract 

Coke Oven 

Roofing.Tar 

Caterpillar 3304 

Diesel Engine· 

Nissan Datsun 220-C 

Diesel Engine 

Oldsmobile 350 

Diesel Engine 

Volkswagen Turbocharged 

Rabbit Diesel Engine 

Benzo(a)pyrene 

Positive Control 

Tumor Initiation 

in SENCAR Mice 

(papillomas/mouse 

per mg extract 

at 27 weeks) 

2.101 

(0.090) 

0.535 

{0.024) 

0.011 

(0.009) 

0.528 

(0.023) 

0.156 

(0.034) 

85.28 

(2.71) 

Enhancement of SA7 Viral 

Transformation in Syrian 

Hamster Embryo Cells 

(tranformations/2xlo6 

cells per ug extract/ml) 

0.859 

(0.089) 

2.066 

(0.363) 

0.039 

(0.023) 

0.645 

(0.095) 

0.067 

(0.023) 

0.128 

(0.023) 

540. 

(21.9) 

* Table excerpted from Reference 1. Maximum likelihood estimates of ·- slo.pe o_f~linear. dose response modeL based . upo.n- -Poisson dis tr ibut-ion- ·'. 

Of positive responses •. Asymptotic· standard ef'rors in parenth~·ses.:?'51 :: 
.. . · ... 

Table A-2 

Estimates of Potency of Organic Extracts of 

Diesel Exhaust and Related Environmental Emissions 

in L5178Y Mouse Lymphoma Mutagenesis Assav - Harris* 

Emissions Extract 

Coke Oven 

Roofing Tar 

Caterpillar 3304 

Diesel Engine 

Nissan Datsun 220-C 

Diesel t:.:ngine 

Oldsmobile 350 

Diesel Engine 

Volkswagen Turbocharged 

Rabbit Diesel Engine 

Average Mutant 

Survivors Per - Metabolic 

Activation 

0.726 

(0.152) 

0.311 

(0.121) 

0.156 

(0.038) 

1. 662 

(0.509) 

0.270 

(0.117) 

2.545 

(0.402) 

Coloni.es/106 

ug Extractlml 

+ Metabolic 

Activation 

9.963 

(0.734) 

9.556 

(1.547) 

0.049 

(0.021) 

1. 869 

(0.485) 

0.764 

(0.109) 

1.012 

(1. 200) 

* Table exceroted · from Reference 1. ~aximum likelihood 

estimates. of slop~ of. liryear dose resI?or:ise model based 

upon···" ·Po1ss·o!'\ .~ -a:1s'tr1but1on·· .. .,···of · ·· pos1t·1ve ·- r·espon·se·s • 

Asymptotic standard. errors· in'""parenthese·s: ... - .. - . 
Table A-l 

a-ry of Raaulta FrOll ~ta1Jene9l11 and CArclnogenesl• Aaaay• Ull1¥J 

Dleael Bldlaust Particle Extracta and Other Surrogate Substances - Lowl..am* 

IG'RI' Glll£ ' HIES Kl& LlMl't~ IWB/l'l'l au. 

ASSAY UXlJB ltSSA'l CELL ASSAY ASSAY 

.... tmta/106 ~t.anta/106 ~t.atlon Tr mutfonMtlon IWBl'BR lHIMl Sl!H:AR Kl& SUN 

Revert.ants hir !llcvlvor• Per Survivors Per rr..,.,.:y FrecJW!nCY CELL Nmi'Y ASSAY I I 

100 !!I Blttract U!l/al Blrtr act ~ Extract x 105 x los Transformtlorw Papll.l.cmus Care""-

Surrogate Wlth ii/O Mith Nth M/t) Mith W/t) with w/t) · Per 2 X 106 a.Us per Mouae per tbl8e 

f!!gx>aure !:! !:! !:! !:! S-9 !:! !:! S-9 S-9 Per UIJ/!l Extract at 1 11!J at 1 11!1 

Dleael lOO 500 0.2 1.9 1.7 0.5 0.51 -0.5 O.l 0.6 0.25 0.05 

Vehicle 

Eld'8Ullt 

O*e °""" 2SO 10 6 10 0.1 n.•. B.l 2.5 2.1 0.86 2 0.1 

Babaiana 

lmfll¥) 100 0 6 10 O.l 1.7 l.l 1.1 0.6 2.1 o.• 0.1 

TU Vap>rs 

Cigarette 100 0 0.06 0.5 0.6 n.a. n.a. n.a. n.a. 0.6 0.2 O.l 

8iloke 

Qinderulate 

Urban SOot 100 n.a. n.a. :n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. 

l ~ 

• 'ftils tible wa eJOtrpted fr011 Reference 15.; 

! .1 

l 

j, l . ' 
.Table A-4 

- Summary of Results for Human Lung Cancer 

Annual Unit Risks - EPA* (risk/ug organics/m ~ 

Emission Source Lower Limit Best Estimate UEEer 

Coke Oven[aJ 6.6 x io-6 1.2 x io-5 2.0 

Roofing Tarfa] 1.3 x io-6 4.7 x io-6 9.4 

Cigarette Smoke (bJ 1.7 x 10-8 2.9 x lo-8 [cl 4.9 

Limit 

x io-5 

x io-6 

x io-8 

* Th1s table was excerpted from Reference 16 in which 

lifetime risks were presented. These risks have been 

converted to annual risks by dividing by the median life~pan (76.2 years) •. 

[a] 95 percent confidence intervals for linear model. 

[b} Bounds from linear and quadratic model. 

(c] Geometric mean of the limits. 
Table A-5 

Summary of Dose-Response Slopes for 

Emission Extracts Short Term In-Vitro Bioassays - EPA* 

Mutation in 

L5178Y Mouse 

Lymphoma Cellsfbl 

(-MA) (al (+MA) 

SCE in 

CHO Cells[c] 

(-MA) (+MA) 

Ames Salmonella 

Typhimuriium TA98fdl 

Samo le ( - ~.A) (+MA) 

Human 

Carcinogens: 

Coke Oven 

Roofing Tar 

csc 

Diesels: 

Nissan 

Volkswagen 

Rabbit 

Oldsmobile 

Caterpillar 

0.71 

0.39 

0.39 

4.2 

0.98 

1.2 

0.25 

12. 

17. 

0.79 

2.9 

0.72 

1.3 

0.063 

0.41 

0.12 

0.12 

0.03 

0.02 

0.08 

0.30 0.071 

0.075 0.030 

Neg 0.017 

0.011 Neg 

* This table was excerpted from Reference 16. 

0.7 

Neg[e] 

Neg 

11. 

3.8 

2.2 

0.38 

[a] MA = Metabolic ~ctivation. 

[b] Mutation frequency (TK mutants/106 surviving cells)/ug/ml. 

[ c 1 SCE/cell/ug/ml, (-MA) was a 21. 5-h exposure and (+MA) was 

-1. l . 

0.86 

0.57 

13. 

3.0 

1.5 

0.31 

a 2-h exposure. ,, ..... _.,, .. ~ .. ,. 

(d] Revertants/ug (from simple linear regression analysis). 

(e] Neg= Negative, i.e., no response. 
Table A-6 

SENCAR Mouse Skin Tumor Initiation and 

Complete Carcinoqenesis by Emission Extracts* 

Sample 

Human 

Carcinoqens: 

Co.ke Oven 

Topside ·Roofing Tar 

csc 

Diesels: 

Nissan 

Volkswagen 

Rabbit 

Oldsmobile 

Caterpillar 

Gasoline 

Catalyst 

Skin Tumor Initiation 

Multiplicity Incidence Data (dose 

Data (papillomas/ in mg yielding 25% 

mouse at 1 mg) mice with papillomas) 

2.l[d] (1.0) 

0.4l[d] (0.20) 

0.0024[a,e) 

(0.0011) 

0.59[d1 (0.28) [f] 

0.24[a] 

0.3l[aJ 

Neg[h] 

0.16[b) (1.0) 

0.7l[b] (0.22) 

92. (0.0017) 

0.6l(bJ (0.26) 

* This table was excerpted from Reference 16. 

Skin Cancer 

Incidence Data (dose 

in mg yielding 25% I 

mice with carcinoma 

4.0(c] 

(q] 

• [a] Values based directly on papilloma multiplicity data at 1 mg. 

( b] 

r c 1 

[dl 

[eJ 

r f 1 

[g) 

[h) 

Values based on statistical analyses of the ·papilloma inciden5~,.:~,~~ .. ~::ov~:· 

log-Probit model with background correction. 

Values based on carcinoma incidence data. 

Values based on statistical analyses of the papilloma multiplicity data 

by a Poisson model with background correction. 

Nesnow, Triplett, and Slaga, unpublished observations. 

Values in parentheses are normalized to the coke oven topside sample. 

Nissan produced carcinomas in 4 percent of the . mice at the 4-mq/weelc 

dose level. 

Neg = negative levels. 
Table A-7 

Comparison of Relative Potencies of 

Emission Extracts in Several Bioassav Systems - EPA* 

Mutation 

Mouse Mouse in Mouse Mutation 

Skin Tumor Skin Lymphoma in Ames TA98 

Emission Source Initiation Cancer Cells(+MA) [a] 

Coke Oven[bl 1.00 1.00 1.00 

Roofing Tar 0.20 0.20 1.40 

Clqarette 

Smoke 0.0011 NT{c] 0.066 

Nissan 

Diesel 0.29 0.10 0.24 

* . This table was excerpted from Reference 16. 

[al (+MA) = With Metabolic Activation. 

[b] Absolute value of annual unit risk is 1.2 x io-5. 

[cl ·NT·= Not Tested. 

[dl ND = No Data. 

::7 .. ·-: 

(+MA) [a] 

1~00 

0.78 

0.52 

12.00 

Human 

Lung 

Cancer 

1.00 

0.39 

0.0024 

~D[dl 
Table A-8 

Comoarison of Relative Potencies of 

Emission Extracts in Several Bioassav Svstems - EPA* 

Mutation in SCE in Mutation ii:i Net 

Diesel Mouse Lymphoma CHO Cells Ames TA98 Relative 

Source r.ells ( +~~) (a 1 (+~~A) (al (+MA) (a 1 Potencv 

Nissan[b] 1.00 1.00 1.00 1.00 

Volkswaqen n.25 0.42 0.23 0.30 

Oldsmobile 0.45 0.24 0.11 0.27 

Caterpillar 0.022 NEG(c] 0.023 0.015 

* This table was excerpted from Reference 16, except for the 

last column, which was derived from the final risk 

estimates of Table 3. 

[al (+MA) = with metabolic activation. 

[b] Absolute value of annual unit risk is 0.58 x io-5. 

rel ~EG = ne~ative {i.e., no response). 
Table A-9 

Ames Test Results on Diesel 

Vehicles (usinq TA-98 strain) 

Studv/Reference 

Landman/Wagner[l7] 

Vehicles 

In-use Oldsmobiles 

( 40k miles) 

Peugeot 

Prototypes 

(Mercedes-Benz, 

Peugeot) 

McMahon, et.al. [18]. VW Rabbit 

Hyde, et.al.[19)* GMC 

VW Rabbit 

Mercedes-Benz 

Others 

Claxton[20] Diesel Engine 

Diesel Vehicles 

Overall Mean -·· 

f.(ean 

Specific Activity 

(revertants/uq SOF) 

(-MA) (+MA) 

13.7:t_7.4 

6.46+4.49 

11.1+'3.9 

5.84+6.6 

l.24:t_0.52 

1.10+0.77 

0.97+0.27 

0.97+0.24 

4.35+0.n4 

6.96+4.06 

:-:5~.2.7 .. 

8.22+2.75 

2.08+0.46 

8.66+'4.59 

5.26+1.57 

6.06 

* All vehicles in this study were in-use diesels. 
Table A-ltJ 

Total Particulate and SOF Emission 

Rates for LDDVs With and Without Ceramic Traos 

Manufacturer 

Vehicle Trap 

(22] Ford -- ( 1) 

f23JMercedes Corning 

( 2) 

[23] Datsun NGK (2) 

( 2 41 GM Corning 

( ) Reference 

(1) mq/mi 

( 2) g/km · 

Without Trao 

TPM SOF 

436 309 

303 138 

436 309 

303 138 

0.25 0.018 

0.17 0.'145 

, .... -~ .,. .... .......... .. . ..• -~ ... . 

With Tra2 

TPM SOF 

192 173 

63.6 56.6 

91. 6 83.4 

75.8 63.S 

0.050 0.004 

0.040 0.012 

Average = 

.+- % Chanoe 

TPM §QI 

-56 -44 

-79 -59 

-79 -73 

-75 -54 

-80 -78 

-90 -75 

-76 -73 

-89 -77 

-97 -92 

-80 -69 
Table A-11 

Total Particulate and SOF Emission Rates 

for HDDV and qooEs With and Without Ceramic 

Manufacturer 

Vehicie Trac 

[25]Caterpillar 

Engine Corning 

( l) 

- ---

r 2 6 J DDAD 

Coach Engine Corning 

( l) 

[26] GMC Corning ·c:oa-ch 

Vehicle 

[ ] Reference 

(1) a/kw-hr 

(2) g/km 

( 2) 

(.a~> .. -,. ;F.,P A ~e's t - M o·d e :·3 

Without Trac With TraE 

TPM SOF TPM SOF 

1. 04 7 - 0.932 1.039 0.972 

0.482 0.377 0.173 0.137 

0.241 0.038 0.015 0.002 

0.795 0.026 0.022 0.0005 

0.792 0.133 _0.022 0.006 .. 1.864 0.969 0.139 0.067 

0.70 0.20 0.15 0.11 

0.86 I). 49 0.28 0.24 

0.70 0.39 (). 3 0 0.25 

0.75 I). 4 0 0.29 I). 25 

0.78 0.54 0.25 0.20 

5.48 0.46 0.589 0.073 

4.24 0.28 0.313 0.035 

4.4 0.31 0.350 0.040 

6.2 0.41 0.430 0.049 

Average = 

~. - __ .r. 

Tr a cs 

+ % 

-TPM 

-0~76 

-64.l 

-93.8 

-97.2 

-97.2 

-92.5 

-78.6 

-67.S 

-57.l 

-61.3 

-68.0 

. -89.3 

-92.5 

-92.1 

-93.l 

-76.3 

Chanqe 

SOF 

+4.3(a) 

-63.7 

-94.7 

-98.1 

-95.5 

-93.1 

-45.0 

-51.0 

-35.9 

-37.S 

-63.0 

-84.l 

-87.5 

-87.l 

-88.1 

-68.0 
Table A-12 

SOF as Percent of Total Particulate 

for LDOVs With and Without Ceramic Traps 

Manufacturer Without With + 

Vehicle Trap Trap Trap P~t'cent Change 

[221 Ford 70.9 90.1 +19.2 

45.S 89.0 +43.S 

70.9 91.0 +20.l 

45.S 83.8 +38.3 

[231 Mercedes Corninq 7. 2· 8. 0 - . +0.8 

[23] Datsun NGK 26.S 30.0 +3.5 

[ 2 41 GM Corning 25.S 55.l +29.6 

25.0 57.0 +32.0 

Average = +23.4 

( 1 Reference 
·Table A-13 

SOF as Percent of Total Particulate 

for HDDV and HDDEs With and Without Ceramic '!'raps 

Manufacturer Without With + 

VeFiicie Trap Trap Trao Pe·rcent Chanae 

[25]Caterpillar 

Engine(a) Corninq R9.0 93.6 +4.6 

78.2 79.2 +l.O 

15.8 13.3 -2.S 

3.J 2.3 -1. 0 i~.e 27.3 +10.S 

52.0 48.2 -3.8 

[26] OOA.O 

Coach Engine r.orning 28.9 75.0 +46.l 

56.8 84.4 +27.6 

56.l 82.7 +26.6 

5 6·. 2 82.9 +26.7 

64.6 81.8 +17.2 

[261 GMC 

.Coach Vehicle Corninq 8.4 12.4 +4.0 

6.6 11. 2 +4.6 

7.1 11.4 +4.3 

6.6 11.4 +4.8 

- Average = +11.4 

( a ) cater pi 11 a r test modes : EPA 3 , 4 , :_5 , 9 ·' · · i-o ,: 11. 
Table A-14 

Gaseous HC Emissions for LDDVs 

With and Without Ceramic Traps 

Manufacturer 

Vehicle Trac 

(221 Ford (1) 

(171 Toyota (1) NGK 

[17] Mercedes Corning 

( l) 

[23] Mercedes Corning 

( 2) 

[231 Datsun ( 2) ~GK 

[ 241 GMC ( 3) r.orn ing · 

· [ ··] Indicates reference 

( l) g/mi 

(2) a/km 

(3) ppm-C3 

Gaseous ~c Emissions 

without With 

Trac Trap + Percent Chanae 

0.99 

0.61 

0.99 

0.61 

0.405 

0.223 

0.266 

0.092 

0.0970 

0.20 

38 

26 

26 

27 

28 

0.90 

0.60 

0.63 

0.47 

0.313 

0.161 

0.230 

0.091 

0.0645 

0.18 

38 

26 

25 

26 

28 

_-9. l 

-1.6 

-36.4 

-22.9 

-22.7 

-27.8 

-13.5 

-1.l 

-33.S 

-10.0 

0 

0 

-3.9 

-3.7 

0 

Average = -12.4% 
Table A-15 

Gaseous RC Emissions for RDDV and 

HDDEs With and Without Ceramic Traps 

Manufacturer Gaseous HC Emissions 

without with 

Vehicle Trao Trao Trap 

[ 2 5 J Caterpillar · · Engine Corning(l) 1.917 2.152 

0.771 0.591 

0.253 0.178 

0.265 0.111 

1.305 o .. 510 

2.926 2.077 

[26] DDAD 

Coach Enqine Corning(l) 1. 64 1.68 

1.85 1. 88 

1.91 1.89 

1.90 1.89 

1.93 1.83 

°(26] GMC Coach 

Vehicle Corning·(2) 1.78 1.10 

1.52 1. 01 

1.56 1.02 

2.25 1.47 

+ 

Pez:cent Change 

+12.3 (a) 

-23.4 

-29.6 

-58.l 

-60.9 

-29.0 

+2.44 (b) 

+l.62 

-1.05 

-0.53 

-5.18 

-38.2 

-33.6 

-34.6 

-34.7 

Average ~ -22.17% 

[ l Reference 

(1) g/kh-hr 

(2) g/km 

(a) EPA Mode 3 (test condition) 

(b) 13-Mode composite 

; ·. 
Table A-16 

·Gaseous RC Emissions During Durability Test 

of Corninq TraE on Mercedes 30050 [reference 231 

HC Emissions (a/km) 

without with 

VMT (1000s km) Trap Trao + Percent Cha nae - 0 0.11 0.080 -27 

8 0.11 0.070 -36 

, 16 0.12 . 0.080 -33 

24 0.09 0.060 -33 

32 0.08 0.070 -12 

40 0.09 0.055 -39 

48 0.09 0.070 -22 

56 0.10 0.053 -47 

64 0.09 0.060 -33 

72 0.09 0.041 -54 

80 0.10 0.068 -32 

Average = -33.5% 
Table A-17 

Ames Test Bio-Activity Data on SOF for LDDV 

_With and Without Ceramic Trao [reference 2 71 

Without Trap With Trap + % Chanqe 

Test Condition (a)per per(b) per per - -per per Trap; Engine mass VMT mass ~T mass· VMT - - Clean Trap, A 1.9 5.9 3·.7 6.4 +94.7 +8.5 

Clean Trap, B 2.0 2.8 5.1 3.0 +155· +7.1 

Loaded Trap, A 1.9 5.9 3.6 3.0 +89.5 -49.2 

tc>-a-ded Trap, B 2.0 2.8 4.3 2.9 115 +3.6 - Average • +113.6 -7.5 

(a) Bio-activity per mass, units of revertants/ug SOF. 

(b) Bio-activity per VMT, units of revertants/mile x io-S. 
Table A-18 

Ames Test Bio-Activity Data on SOF for 

HOOE With and Without Ceramic Trac [reference 251 

Without Tra2 With Trae - :!: % r.hange (a)per per(b) per per per per EPA Test ~ode mass work mass work mass· work 

3 0.408 363 0.392 365 -3.92 - +0. 5 5 

4 0.251 92 l. 404 193 +459 +110 

5 1.319 54 1.524 3.3 +15.S -94.0 

9 0.851 22 2.482 2.6 +192 -88.2 

10 o.762 101 1. 620 10.7 +113 -89.4 

11 0.357 325 1.250 87 +250 -73.4 - Average = +170.9 -39.1 

(a) Bio-activity per mass, units of revertants/ug SOF 

(b) Bio-activity per work, units of revertants/kw-hr 
Table A-19 

Temperature Range Distribution of SOF for 

HOOE With and Without Ceramic Trap [reference 26] 

Percent Boiling-Point TemEeraturef°C 

Mass Released without Trap with Trap + % Change - IBP 307 340 -+-lo .8 

10 391 396 -+-1.28 

20 412 418 -+-1.46 

30 - - ·- 432 435 +0.69 

40 452 450 -0.44 

so 474 465 -1.90 

60 503 480 -4.57 

70 542 499 -7.93 

80 607 530 -12.7 
Table A-20 

BaP Emission Rates for HOO Engine and Vehicle 

With and Without Cornina Ceramic Trap [reference 26) 

Test Conditions 

Coach (1) 

Engine: 

In-Service 

Coach (2): 

7-mode 

Transient 

Bus Cycle 

Transient 

Bus Cycle 

(l) BaP, uq/kw-hr 

( 2) BaP, uq/km 

BaP Emission Rate 

without with 

Trao 

0.04 

0.08 

0.11 

0.050 

0.008 

Trap 

0.12 

0.28 

0.11 

0.055 

0.022 

·+ % Chanae 

+200 

+250 

o~o 

Average • 150% 

+9.6 

+175 

Average = 92% 
Table A-21 

Trap Removal-Efficiencies of 

Carcinoaens With Resoect to Total Particulate 

Ratio of 

Average % Change Percent Changes 

Carcinoaen Studv Carcinogen TPM Averaae Range 

SOF · Ford -56.5 - 7·7 • () .74 .72-.75 

Mercedes -76.5 -85.0 .91 .83-.98 

Datsun -73.3 -76.S .96 .96 

GM -84.5 -93.0 .91 .87-.95 

Caterpillar -89.0· -89.0 1.0 .98-1.01 

DDAD Engine -46.5 -66.5 .70 .57-.93 

GMC Coach -86.7 -91.8 .94 .94-.95 

Mutagens Ford -7.5 -72.3 .10 .10 

Caterpillar -86.3 -89.0 .91 .79-1.0 

BaP DDAD Engine +150 -66.5 -2.53 (-4.1)-0 

GMC Coach +92 -91.8 -.99 (-.104-(-1.88) 
Reference 

1. "An Evaluation of Particulate Levels Occurring Under 

1.0/1.2 g/mi NOx Standards for LDDVs and LDOTs," R. Kanner, 

Technical Report, SDSB, U.S. EPA. 

2. "Historical and Projected Emissions, Conversion 

Factor, and Fuel Economy for ~eavy-Duty Trucks: 1962-2002," 

prepared by Ener<:lY and Environmental Analysis·, Inc., for the 

Motor Vehicle Manufacturers Association, December 1983~ 

· .........