P.1 

OAR Box 1875 

Prepped by Ollie Stewart 

Document Number: 

66) ll-F-13 

Docket Number: 

A-90-19 

Printed 12/1/200811:12:48 AM Sheet 66 of 86 
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-«? A-90-19 

ll-F-13 

«i« ° «"'•< V . 

•<*ce^ 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, O.C. 20463 

OCT 7 199 

OfFCEOP 

AiRANOIUOUTlON 

SURTECT: HON Benefits Analysis 

FROM: Thomas C. Kierna: 

Deputy Assistant Administrator 

for Air and Radiation 

TO: Frank Hodsoll 

Deputy Director for Management 

Office cf Management and Budget 

Attached is a draft document representing the Agency's 

effort to utilize available data to estimate benefits of various 

HON options. While we have attempted to make reasonable 

assumptions where possible, the fundamental lack of key 

information related to exposure and toxicity of HON chemicals and 

the complexity of the analysis must be kept in mind. The 

document describes these uncertainties and limitations in detail. 

Agency scientists, including the Office of Research and 

Development, believe that these limitations cannot be overstated. 

In reviewing this document it is important to realize that 

formal benefits analysis is only one factor to be considered in 

decision making. Other, less uncertain information, provide an 

additional basis for decisions. These include the extent of 

overall amission reduction, the cost per ton of these reduction*, 

the extent of existing control, the relation of facilities to 

population centers and consistency with other programs. 

We can discuss the role of this attempted benefits 

assessment and these other decision factors at our meeting next 

week. Our apologies for the additional time required to generate 

this analysis. 
P.3 

I* 

HON BENEFITS ASSESSMENT 

INTRODUCTION 

This analysis has been conducted at OMB's request to 

determine the extent to which conclusions can be drawn from 

available data concerning the net benefits and costs of the 

Hazardous Organic NESHAP (HON). While the Agency has attempted 

to make reasonable assumptions where possible, the fundamental 

lack of key information related to exposure and toxicity of HON 

chemicals, the complexity of the analysis and time constraints 

strongly limit the utility of the results. Agency scientists, 

including the Office of Research and Development, believe that 

these limitations cannot be overstated. 

In particular, the available information on emissions of 

specific HON chemicals from emission points do not provide an 

adequate basis for calculating population exposure. The fact 

that the emissions data are limited to a subset of emission 

points, the limitations in the toxicity data base and a range of 

other factors described below all contribute to the great 

uncertainty surrounding these estimates. In addition, the lack 

of data and available methodology for endpoints other than cancer 

mortality result in a failure to include potential benefits for 

noncancer health endpoints. 

With these broad cautions in mind, the following 

presentation provides a more detailed discussion of uncertainties 

inherent in the analysis. 

Evaluation of Exposure 

A complete analysis would require knowledge of sourcespecific speciated emission data (i.e. a knowledge of both the 

amount and identity of chemicals being emitted from sources) as 

well as information on the location and activities of individuals 

around each HON facility. These data would be necessary to 

support appropriate characterization of exposure to individuals 

around HON sources. Alternatively, comprehensive measured or 

monitored data would be required to characterize the exposures of 

such individuals. Because of the broad range of chemicals and 

sources covered by the HON (about 110 listed hazardous air 

pollutants - HAPs - from 324 known facilities), such an 

assessment is prohibitively complex. Moreover existing data are 

insufficient to support such an analysis. 

Recognizing that a reliable measure of benefits was not 

possible, the Agency instead examined the limited estimated 

emissions data available from a subset of pollutants and emission 

points at 88 facilities, in order to provide some insight into 

the range of values which the benefits may encompass. As such, 

the analysis cannot be described as a true assessment of the 

benefits of the HON rule. It is critical in evaluating this 
P.4 

analysis that the limitations and ranges of uncertainty described 

in this report be kept in mind. 

Evaluation of Health Endpoints 

The analysis has also been limited by the lack of 

significant toxicity data on many HON pollutants. Because of 

limitations in methodology, the asssessment focused on cancer 

incidence, relying upon the available carcinogenicity data. Less 

than half of the 110 HAPs have been tested for carcinogenicity. 

For most chemicals with quantitative risk estimates, potency 

estimates rely upon animal dose-response data, and the Agency has 

used unit risk estimates developed in compliance with its Cancer 

Assessment Guidelines. 

With respect to noncancer effects such as developmental 

toxicity or neurotoxicity, adequate data exist to assess risk for 

even fewer HON pollutants. Thus the full range of health benefits 

cannot be characterized. While available methodologies do not 

permit a quantitative assessment of noncancer effects, this 

benefits assessment presents some data suggesting that exposures 

to many HON chemicals exceed benchmark levels generally 

recognized as indicators of potential risk. 

Uncertainties 

It must be kept in mind when reviewing this benefits 

assessment that the results are contained within broad ranges of 

uncertainty, and that it remains difficult even to characterize 

the bounds of those ranges. While the Agency believes that costs, 

which are better understood, are likely overstated (see below), 

the benefit analyses incorporate a variety of variables, some of 

which may be overstated, and some understated. In addition, an 

unknown portion of the potential risk has been left unquantified 

and uncharacterized. 

The following is a general summary of specific uncertainties 

inherent in this analysis: 

o The use of unit risk estimates (UREs - i.e. potency 

factors) for carcinogens would tend to overstate risk 

to an unknown degree, since potency factors are 

estimates of upper-bound risk for low-dose exposures. 

o 1980 census data was used in the analysis. The 

population has grown since 1980; therefore more people 

would be expected to experience adverse health effects. 

o There exist little data on identification of specific 

chemicals emitted and the amounts of those chemicals 

emitted for individual HON facilities. Assumptions have 
P.5 

been made for this analysis which may result in a 

highly inaccurate portrayal of true risk. 

o In determining population exposure, a screening model 

was used to estimate the number of people living within 

50 km of the subset of 88 facilities. This subset was 

selected for modeling because facility locations 

(latitudes and longitudes) were known. It is not known 

how representative those facilities are of all HON 

facilities. 

o The risk analysis provides estimates of the risk 

associated with exposure to 28 percent of process vent 

emissions and 20 percent of wastewater emissions. This 

is only a small subset of emissions from all HON 

facilities. 

o The emission estimates were estimated for chemical 

compounds that are either products, co-products, or byproducts of the process. Compounds that are present in 

the feedstock or that are intermediates produced during 

the process are not accounted for. 

o Cancer risk includes estimates for only those compounds 

that are designated known, probable, or possible human 

carcinogens. Compounds with insufficent data to 

determine carcinogenicity are excluded. 

o Synergisms and antagonisms among hazardous air 

pollutants (HAPs) were not considered in the analysis. 

Factors That Lead to Overestimation of Cost 

o Cost estimates assume one control device for each 

emission point at a facility. In practice, points are 

often combined for cheaper co-control (i.e. several 

lines may vent to one incinerator). 

o Cost estimates give no credit for cost savings due to 

emissions averaging. 

o Estimates assume the most expensive means of 

compliance. 

o Cost estimates do not take into account that the 

standard uses the total resource effectiveness (TRE) 

format for vents, which allows facilities to comply 

through changes in equipment or operations at lower 

cost. 
P.6 

"AFT 

ESTIMATING EXPOSURE 

Human Exposure Model 

A numerical expression of public exposure, i.e. of the 

numbers of people exposed to various predicted concentrations of 

HAP compounds, is needed to help estimate the benefits of 

controlling HAP emissions that are released into the ambient air. 

The numerical expression of public exposure is based on two 

estimates: (1) an estimate of the magnitude and location of 

annual average air concentrations of the HAP emissions near 

emitting sources; and (2) an estimate of the number of people 

living near emitting sources. 

The Human Exposure Model (HEM) was used to make these 

quantitative estimates of public exposure. The HEM consists of 

an atmospheric dispersion model that includes meteorological data 

(National Weather Service) and population distribution estimates 

based on 1980 Bureau of Census data to calculate public exposure. 

The dispersion model in HEM used data for model plants that 

were modeled at each of 88 HON facility locations (latitude and 

longitude). The model plant is constructed to represent realistic 

plant parameters where actual parameters vary. Inputs to the HEM 

dispersion model for each model plant included: (1) model plant 

emission rate for total HAP from waste water treatment and 

process vents; (2) release height of 10 meters for process vents; 

zero meters for waste water; (3) exit velocities of one 

(uncontrolled) and fifteen (controlled) meters/second for vents 

and 0.1 for waste water; (4) stack gas temperatures of 298 

(uncontrolled) and 999 (contolled) degrees Kelvin; (5) building 

cross-sectional area of ten square meters; and (6) for process 

vents, inside stack diameter of 1.0 meter. 

Based on specification of a latitude and longitude to define 

each plant's location, meteorological data (an annual average 

estimate of five years worth of data is typical) from the nearest 

airport of the 314 airports contained in the HEM is brought into 

the analysis. The meteorological data as well as the model plant 

emission and stack information are used to estimate the 

concentration and distribution of HAP from distances of 200 m to 

5 0 km from the emitting source. Specifying the latitude and 

longitude also brings into the analysis the population 

distribution near the plant. 

The population database consists of population centroid 

locations and the 1980 population rrepresented by each centroid. 

A centroid is the population weighted center of a census unit and 

by definition people generally live closer to and further from 

the emitting source than the centroid. Census units vary in size 

from a city block to over 300 square miles. HEM identifies the 
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• • 

;-l 

census units that fall within a 50 Jem radius (about 30 miles) of 

the emitting source. 

The HEM multiplies the concentration of HAP at ground level 

at each of 160 receptors around the plant by the number of people 

exposed to that concentration to produce exposure estimates. The 

HEM takes an annual snap shot of risk and therefore assumes that: 

(1) conditions leading to the predicted concentrations do not 

change and thus the annual average exposure for the year in 

question persists for the duration of the averaging time of the 

URE which is a lifetime equal to 70 years, (2) people stay at the 

same location the entire year and are exposed continuously to the 

predicted HAP concentrations, (3) the terrain around the plant is 

flat, and (4) concentrations of HAP are the same inside and 

outside of the residence. 

Exposure Uncertainties 

Emissions per Model Plant 

Neither the amount of specific HAP compound emitted nor 

which HAP are emitted from specific facilities are known. 

Some of the uncertainties associated with the model plant 

include: representativeness of the model plant — assuming that 

ambient air begins 200 meters from a significant emission point 

may overstate exposure for larger chemical plants and understate 

exposure for smaller chemical plants; the location of emission 

points about plant property; representativeness of emission point 

characteristics, e.g. stack height, etc.; representativeness of 

the meteorology from the nearest meteorological site to that of 

the facility; and how well the dispersion model in HEM predicts 

ambient HAP concentrations. 

Population Exposure 

The basic assumptions implicit in the methodology are that 

all exposure occurs at people's residences, that people stay at 

the same location all year, that the conditions that lead to the 

predicted ambient air concentrations remain unchanged for the 

averaging time of the URE, e.g. 7 0 years, and that the 

concentrations are the same inside and outside the residences. 

From these assumptions it can be seen that public exposure is not 

based on actual data. 

The Population 

The following are relevant to the exposed population: 

o Studies show that all people are not equally 

susceptible to pollution and cancer. There is no 

numerical recognition of the "most susceptible" subset 

of the population exposed. 
P8. 

AT' 

o Studies show that whether or not exposure to a 

particular carcinogen results in cancer may be affected 

by the person's exposure to other substances. The 

public's exposure to other substances is not 

numerically recognized. 

o Workplace exposures are not numerically approximated. 

o Noninhalation exposures are not numerically 

approximated. 

o Studies show that there is normally a long latency 

period between exposure and onset of cancer. This has 

not been numerically recognized. 

o The people exposed are not located by actual 

residences. They are located in the Bureau of Census 

data for 1980 by population centroids of census 

districts. 

Ambient Air Concentrations 

The following are relevant to the estimated ambient air 

concentrations used in this analysis: 

o Flat terrain was assumed in the dispersion model. 

Concentrations much higher than those estimated could 

result if emissions impacted on elevated terrain near a 

plant. 

o The estimated concentrations do not account for the 

additive impact of emissions from plants located close 

to one another. 

o Meteorological data specific to plant sites are not 

used in the dispersion model. As explained, 

meteorological data from the National Weather Service 

station, usually an airport, nearest the plant site are 

used. Site-specific meteorological data could result in 

significantly different estimates of predicted 

concentrations. 

o The emission rates are based on assumptions about the 

concentrations of specific HAP compounds in total HAP 

soup emissions. 
P.9 

i ' ' ' '\H 

ESTIMATING CANCER INCIDENCE 

There are a variety of effects categories associated with 

the emissions of hazardous air pollutants (HAPs). This section 

of the analysis focuses on cancer incidence only. 

Annual Cancer Incidence 

The expression of risk used here is annual cancer incidence, 

a measure of aggregate risk. Aggregate risk is the summation of 

risks to people estimated to be living within 50 km of an 

emitting source from exposure to HAPs through inhalation. It is 

calculated by multiplying (modeled ambient concentrations of the 

pollutants) x (HON emission IUR) x (total population exposure — 

the sum of the number of people exposed to the range of modeled 

ambient concentrations times those respective concentrations). 

This estimate reflects the number of annual excess cancers among 

the total population if the conditions leading to the exposure do 

not change from year to year, and the many other assumptions 

required by quantitative risk assessment are correct. 

This analysis includes only those HAPs with carcinogenic 

classifications of A, B, or C (known, probable, or possible human 

carcinogens). Of 29 HAPs with A, B, or C classification, 20 have 

inhalation unit risk estimates (IUR) upon which to base cancer 

risk (the inhalation unit risk represents the excess, lifetime 

cancer risk due to the continuous, lifetime exposure to one unit 

(1 ug/m3) of carcinogen. 

To include the remaining 9 HAPs in the analysis, a default 

IUR was calculated and applied to these 9 HAPs based on the 

following rationale: 

The existing IURs appear to be log normally 

distributed. Therefore, the central tendency of this 

distribution can be approximated by using the geometric 

mean or the median value of this distribution. In this 

case, both values were very close (1.8xl0~5 vs. 2.0x10" 

5, respectively), bolstering the geometric mean as a 

reasonable value to use as the default value. 

The 29 HAP IURs (including the default value) were then 

weighted by applying a value of their estimated emission. The 

estimated emission values were calculated as follows: 

The amounts of an individual HAP found as a product, 

co-product, or by-product (regardless of process) were 

estimated from the HON database. The ratio of this 

amount to total HAP emissions from these processes was 

calculated based upon stoichiometric considerations. 

In the absence of actual emissions data for each HAP, 

it was assumed that the proportion of HAP in the 
P.10 

TRAFT 

production process was similar to the proportion of HAP 

in the total HAP emission stream. 

The 29 IURs were weighted by this assumed emission 

proportion normalized to the total HAP emissions. The 

29 HAP carcinogens represented 61% of total HAP 

emissions. The remaining 39% would be HAPs for which 

no data exists to classify a HAP as a carcinogen or 

noncarcinogen or the HAP has known noncancer effects. 

The weighted average of the IURs (2.4xl0~5) was chosen as 

the representative IUR to use in calculating the cancer incidence 

due to HON chemical emissions. Incidence values are presented as 

the annual cancer incidence values, the cancer incidence at 60% 

(because it is assumed these HAPs represent 61% of total 

emissions), and the cancer incidence at 30% and 90%. The range 

of values is appropriate because the emissions of an individual 

HAP from a single site may be as high as 100% or as low as zero. 

Cancer incidences for various control options were 

calculated by multiplying 2.4xl0"5 by the population exposure 

estimates for the various options. 

Uncertainties Surrounding Unit Risk Estimate 

The unit risk estimate (URE) is used by EPA in analyses of 

carcinogens. It is defined as the upper bound lifetime cancer 

risk occurring in a hypothetical population in which all 

individuals are exposed throughout their lifetime (assumed to be 

70 years) to an average concentration of 1 ug/m3 of the pollutant 

in the air they breathe. The risk is not likely to be higher and 

may be significantly lower than that indicated by the URE. Unit 

risk est.imates can be used for two purposes: (1) to compare the 

carcinogenic potency of several agents with one another, and (2) 

to give a rough indication of the public health risk that might 

be associated with estimated air exposure to these agents. 

Most unit risk estimates are derived from animal studies and 

are therefore only approximate indication of the actual risk in 

populations exposed to concentrations of a carcinogen. 

Differences between species (lifespan, body size, metabolism, 

immunological response, target site susceptibility), as well as 

differences within species (genetic variation, disease state, 

diet), may result in the actual risk being much different. In 

human populations, variations occur in genetic composition, diet, 

living environment, and activity patterns. Some populations may 

demonstrate a higher susceptibility due to certain metabolic or 

inherent differences in their response to the effects of 

carcinogens. Also, unit risk estimates are based on exposure to 

a referent 7 0 kg adult. There may be an increased risk with 

exposure to fetuses, children, or other sensitive groups. 

Finally, humans are exposed to a variety of compounds, and the 

8 
P.11 

H 

health effects, either synergistic, additive or antagnostic, of 

exposure to complex mixtures of chemicals are not known. 

The low-dose extrapolation model used and its application to 

epidemiology and animal data have been the subject of substantial 

comment by health scientists. The uncertainties are large and 

are too complex to be summarized here. Significant uncertainties 

associated with the URE include: (1) selection of dose response 

model, (2) selection of study used to estimate the URE, (3) 

presence or absence of a threshold, (4) appropriateness of animal 

model to represent the human population, (5) potency of complex 

mixtures, (6) individual human variability. 
' <J L\ • 

NON-CANCER HEALTH EFFECTS 

Inhalation Reference Concentrations 

Although cancer is of great concern as an adverse health 

effect associated with a chemical or a mixture of chemicals, many 

other health effects may be associated with these exposures. 

These effects may range from subtle biochemical, physiological, 

or pathological effects to gross effects such as death. 

The effects of greatest concern are the ones that are 

irreversible and impair the normal functioning of the individual. 

Some of these effects include respiratory toxicity, developmental 

and reproductive toxicity, central nervous system effects, and 

other systemic effects such as liver and kidney toxicity, 

cardiovascular toxicity, and immunotoxicity. For chemicals that 

give rise to toxic endpoints other than cancer and gene 

mutations, there generally appears to be a level of exposure 

below which adverse health effects usually do not occur. 

In evaluating noncancer risks, frequently a health benchmark 

is compared to estimated exposure levels. Most often, the health 

benchmark used is an inhalation: reference concentration. An 

inhalation reference concentration (RfC) is "an estimate (with 

uncertainty spanning perhaps an order of magnitude) of a daily 

exposure to the human population (including sensitive subgroups) 

that is likely to be without appreciable risk of deleterious 

effects during a lifetime." While there is increased risk of 

adverse effects as exposure exceeds the RfC, such exposure does 

not necessarily mean that adverse effects will occur. The RfC is 

derived from an identifiable no-observed-adverse effect level 

(NOAEL) or lowest-observed-adverse effect level (LOAEL) for the 

critical or most sensitive effect. If derived from an animal 

study, the NOAEL or LOAEL is converted to a human equivalent 

concentration (HEC) to account for uncertainties in the 

extrapolation of this concentration to the general human 

population. For example, uncertainty factors are commonly used 

to account for inter- and intraspecies variability. 

The assessment of noncancer health effects associated with 

chronic exposures to HAPs is based on a direct comparison of the 

chemical-specific health benchmark to the predicted annual 

average ambient concentrations at receptor locations around a 

source emitting HAP. Ambient concentrations that are less than 

the RfC are not likely to be associated with health risks. The 

probability that adverse effects may be observed in a human 

population increases as the magnitude of exposure increases 

(concentration and duration of exposure) and is affected by a 

specific individual's susceptibility. 

For the estimate of cancer reductions, estimates were made 

of exposure to "HAP soup" at 88 plants. These exposure estimates 

10 
P.13 

can be used to estimate exposures to concentrations greater than 

RfC levels before and after regulation if the "HAP soup" can be 

apportioned to allow estimates of the individual pollutants. 

While we do not have individual pollutant estimates for the 

88 plants or for the nation as a whole we do have estimates for 

national production of the 80 products produced in facilities 

covered by the HON that are themselves HAPs. The HON data base 

was used in two different ways to estimate the percentage of 

national production associated with each of the 80 products. The 

first method counts the product only when it is the primary 

product. The second method includes the product whether it is a 

primary product, co-product, or by-product. Each of these two 

sets of percentages are used to apportion the "HAP soup" for the 

88 plants in aggregate. The two methods both assume a 

proportional relationship between emissions and production. This 

is only a very rough approximation. 

The 16 pollutants for which RfCs are currently available 

comprise roughly 25% of emissions by the first allocation 

procedure and 15% by the second. The RfCs for the 16 pollutants 

vary in both the critical effect and the magnitude of the actual 

RfC. 

Once the 80 pollutants are estimated in aggregate for the 88 

facilities, distribution spatially of the emissions is quite 

important because RfCs are non-linear with respect to 

concentration. Thus, if all the "HAP soup" at a particular 

facility is one pollutant, the exposed population will be facing 

a higher concentration that if the "HAP soup" is composed of two 

pollutants with equal shares. It would be an empirical question 

as to whether there would be more people exposed to 

concentrations above the RFC in the single pollutant or the two 

pollutant scenario. Concentrations are higher in the single 

pollutant scenario but pollutant-people-exposures are greater in 

the two pollutant scenario. 

The three scenarios analyzed are: 

o One pollutant at each facility 

o One pollutant for process vents and another for 

wastewater 

o Three pollutants per facility with equal shares by 

mass. 

These scenarios were estimated for the aggregate of the 88 

facilities. Thus, the three scenarios just described should be 

interpreted in terms of average population distribution and 

dispersion characteristics across facilities. For example for 

the one pollutant scenario acetaldehyde was not matched to a 

11 
P.14 

npAFT • • ; i . '•• i i 

particular facility with the requisite fraction of production. 

Instead, the fraction of its production was applied to the 

population exposed to "HAP soup" above its RFC for all 88 

facilities. For the three pollutant scenario the fraction of its 

production was applied to the population exposed to "HAP soup" 

three times its RfC and the result multiplied by three. 

These scenarios are at best rough approximations. They 

ignore cases where the "HAP soup" is comprised of more than three 

pollutants. On the other hand, they also ignore the cumulative 

exposure from multiple HON facilities and concentrations from 

non-HON sources. 

As can be seen from the table the results are more dependent 

on the method for determining percentage of national production 

than for the number of pollutants per facility scenario. All six 

combinations show a significant number of people exposed to above 

RfC concentrations in the absence of regulation. This 

significant exposure is greatly reduced by the pollutant 

reductions associated with the option in the draft proposed 

package. Remember this is only for the emissions associated with 

the wastewater and process vents for the 88 facilities. 

These results should be reviewed as illustrative. 

Significant reductions to exposures above RfC levels in the 

baseline are a likely outcome of regulation. However, knowledge 

of the components of the "HAP soup" is required for reliable 

estimates. Our inability to develop reliable estimates should 

not be misconstrued to infer these non-cancer health effects are 

negligible. 

12 
EXPOSURES ABOVE RFC 

1 Pollutant per Facility 

1 Pollutant for Process 

Vents and 1 for 

Wastewater per Facility 

3 Pollutants per Facility 

(Equal Shares) 

ALLOCATION BASED ON 

PRIMARY PRODUCTION {%) 

BASELINE 

EXPOSURES 

ABOVE THE 

RFC 

1,000,000 

1,200,000 

1.400,000 

REDUCTIONS IN 

NUMBERS OF 

PEOPLE ABOVE 

THP RFC 

800,000 

900,000 

1,200,000 

ALLOCATION BASED ON 

PRODUCTS. CO-PRODUCTS & 

BY-PRODUCTS (%) 

BASELINE 

EXPOSURES 

ABOVE THE 

RFC 

530,000 

570,000 

620,000 

REDUCTJONS IN 

NUMBERS OF 

PEOPLE ABOVE 

THE RFC 

440,000 

480,000 

560,000 

Reductions in exposure are estimated for pollutant reduction associated with going from the baseline 

to the option in the draft proposed package. 
1RAFT 

MORTALITY VALUATION 

The purpose of this section is to describe the consequences 

of quantifying some of the anticipated exposures, risk 

reductions, and valuations from reductions in HAP emissions for a 

sample of selected emission points and effects categories. The 

characteristics of the sample, the other aspects of the 

methodology, results, as well as conclusions and qualifications 

are described below. 

Despite incomplete coverage of the benefits, the floor for 

process vents and option 1 for wastewater emission points are 

preferred on allocative efficiency grounds to present control 

levels. Data paucities (incomplete coverage of the benefits) 

preclude a definitve statement as to whether further controls for 

process vents and wastewater facilities improve or worsen 

economic welfare given the criterion of allocative efficiency. 

Sample of Emissions, Emission Points, and Effects Categories 

This section of the addendum characterizes the sample by 

comparing the universe of emissions, emission points, and effects 

categories to those of the sample. 

Emissions. Estimated baseline HAP emissions for the HON are 

portrayed by the histograms on Figure 1. These emissions come 

from equipment leaks, process vents, storage vessels, wastewater 

collection and treatment operations, and transfer and loading 

operations. Of this total, nearly 90% are from process vents and 

wastewater collection and treatment operations, with process 

vents accounting for nearly 50% of total baseline emissions of 

HAP from existing sources. The process vents and wastewater 

emission points account for a similar portion of non-HAP VOC 

baseline emissicns. This section focuses on a subset of emissions 

from the process vent and wastewater emission points. 

Emission Points. To conduct exposure analyses, estimate 

risk reductions, and value those reductions, much underlying data 

are required. One such data element is the geographic location 

of the emission points and associated emissions. For example, to 

translate emission reductions into anticipated concentrations and 

exposures, location specific emissions, meteorological, and 

population information is required. Such information was 

available at the plant level for a subset of process vents and 

wastewater emission points. These are plant level emission 

points with known latitude and longitude coordinates. The subset 

of process vents accounts for 28% of baseline emissions, 36% of 

annualized control cost and 24% of all individual process vents. 

The subset of wastewater emission points accounts for 20% of HAP 

emissions, 29% of annualized control cost, and 14% of all 

individual wastewater emission points. 

14 

r> r~\» r T 
TOTAL HON EMISSIONS 

By Emission Point 

Total HON Emissions (Mg/yr) 

300,000 

250,000 

200,000 

150.000 

100.000 

50,000 

0 

ST W W EL PV 

Emission Point 

MvM. 

TR 

TJ 
P.18 

n )RAFT 

Effects Categories. There are a variety of effects 

categories associated with emissions of HAP and non-HAP VOCs. 

These are displayed on Table 2. With reductions in HAP and nonHAP VOC emissions, there would be anticipated reductions in 

concentrations, exposures, effects, and economic damages. But, 

there is also the potential for an increase in nationwide NOx 

emissions in the fifth year of 17,000 Mg as well as an increase 

in CO emissions of 1,760 Mg. However, these emission quantities 

are small in comparison to the corresponding decreases in HAP and 

non-HAP VOCs emissions. Such decreases are estimated nationally 

at 1,509,000 Mg from process vents and wastewater emission points 

in the fifth year. 

This analysis explicitly monetizes only one effect category: 

mortality due to chronic exposure to HAPs. Incomplete coverage 

of the benefits does lead to ambiguities regarding the allocative 

efficiency aspects of control options. 

16 

•A . 
P.19 

POTENTIAL PHYSICAL EFFECTS CATFHORIES FOR 

THE HON REGULATION 

Human Health Effects 

Mortality Due to chronic Exposure 

Mortality Due to Acute Exposure 

Morbidity Due to Chronic Exposure 

Morbidity Due to Acute Exposure 

Reduced Activity Days 

Human Welfare Effects 

Worker Productivity Losses 

Odors 

Non-Human Biological Effects 

Agriculture 

Forestry 

Recreational Fishing 

Ecosystem 

Soiling & Materials Damage 

Residential/Commercial/Industrial 

Facilities 

Miscellaneous Materials 

Climate & Visibilitv Effecrs 

Local Visibility 

Non-Local Visibility 

Climate 

Visibility at Parks 

Transportation Safety 

Direct 

HAP 

1* 

1 

1 

1 

3 

3 

1 

2 

2 

2 

1 

2 

2 

NA 

NA 

3 

NA 

NA 

VOC/ 

Ozone 

3 

2 

2 

1 

1 

1 

2 

1 

2 

3 

3 

1 

1 

NA 

NA 

2 

NA 

NA 

PM 

2 

2 

1 

1 

2 

2 

3 

2 

2 

2 

2 

1 

1 

2 

2 

2 

2 

2 

Legend: 

1 - Documented effect. 

2 - Effect likely, minimal documentation. 

3 - Effect possible, not documented. 

NA - not applicable. 

* - quantified for the HON Benefit Analysis Extension 
>pACf 

Results for Sample of Process Vents and Wastewater Emission 

Points 

The analytical results for the sample of process vents and 

wastewater emission points and selected control options are 

presented below. They result from a combination of emission 

reduction, exposure, and risk assessment results with control 

cost and a range of mortality risk reduction valuation factors 

($1.7 to $9.4 million per statistical life saved in 1989 

dollars). 

Recognize the benefit analysis only monetizes mortality risk 

reductions from chronic exposures to VOC HAPs. The morbidity and 

welfare effects categories exclusive of human health are given no 

weight in the analysis. However, the benefits of non-HAP VOC 

emission reductions are addressed through an implicit valuation 

analysis. 

The results presented below are based on a range of 30 - 90% 

of the HAP-VOC stream being carcinogenic. 

18 
P.21 

Process Vents Sample Assuming 30% to 90% of the HAPS are 

Carcinogenic 

Emission Reduction Range of Reduced 

Mg/year 

Floor 

Option 2 

NSPS 

Prop.Opt. 

Annual Cost 

000's $ 

18,360 

19,404 

20,772 

22,320 

Incremental 

Reduced Emissions 

Floor 

Option 2 

NSPS 

Prop.Opt. 

Floor 

Option 2 

NSPS 

Prop.Opt. 

Mg/year 

64,960 

450 

420 

310 

Incremental 

Control Cost 

000's $ 

18,360 

1,044 

1,368 

1,548 

64,960 

65,408 

65,828 

66,136 

Range of Reduced 

Incremental 

Incidence 

7.9 to 23.8 

.0025 to .0075 

.0023 to .0070 

.0178 to .0534 

Range for Reduced 

Cancers Credit 

000's $ 

13,470 to 223,460 

4.3 to 70.5 

3.9 to 65.8 

30.3 to 502.1 

Cancer Incidence 

7.9 to 23.8 

7.9 to 23.8 

7.9 to 23.8 

7.9 to 23.8 

Range of Incremental 

Implicit Cost/Cancer 

Avoided (000's $) 

770 to 2,320 

138,760 to 416,270 

196,550 to 589,660 

28,980 to 86,960 

Range for Implicit 

Value of non-HAP VOC 

Reductions ($/Mg) 

< 0 to 130 

8,690 to 9,280 

11,630 to 12,180 

12,450 to 18,070 

Average Cost/Mg of 

HAP Removed 000's $ 

Range of Average Implicit 

Cost/Cancer Avoided 000's $ 

770 to 2,320 

820 to 2,450 

870 to 2,620 

940 to 2,810 

* Incidence reduction estimates are carried out to several digits to reveal the calculated differences 

betveen options. The number of digits is not an indicator of the precision of the estimates. 

Floor 

Option 2 

NSPS 

Prop.Option 

280 

300 

320 

340 

19 
Wastewater Sample Assuming 30% to 90% of the HAPs are 

Carcinogenic 

Annual Cost 

000's $ 

Option 1 6,931 

Emission Reduction Range of Reduced 

Mg/year Cancer Incidence 

15,400 2.4 to 7.1 

Incrementa l 

Reduced Emissions 

Mg/year 

;tion 1 15,400 

Range of Reduced 

Incremental 

Incidence 

2.4 to 7.1 

Range of Incremental 

Implicit Cost/Cancer 

Avoided (000's $) 

980 to 2930 

Incremental 

Control Cost 

000's $ 

Option 1 6,931 

Range for Reduced 

Cancers Credit 

000's $ 

4,024 to 66,750 

Range for Implicit 

Value of non-HAP VOC 

Reductions ($/Mg) 

< 0 to 70 

Option 1 

Average Cost/Mg of 

HAP Removed 000's $ 

450 

Range of Average Implicit 

Cost/Cancer Avoided 000's $ 

980 to 2930 

' Incidence reduction estimates are carried out to several digits to reveal the calculated differences 

between options. The number of digits is not an indicator of the precision of the estimates. 

20 
• •-• ' •••-• » 

"' i i 

Conclusions and Qualifications 

Several findings and reservations emerge from this analysis. 

o The strength of this analysis is in the application of 

exposure, risk, and economic analysis principles. 

o However, data paucities in terms concentration response 

and valuation functions preclude definitive statements 

on the allocative efficiency aspects of control options 

for process vents. 

o The net result of the aforementioned data gaps are to 

understate the potential benefits of various control 

options for this sample of process vents and wastewater 

emission points. 

o Despite such limitations, the floor for process vents 

and option 1 for wastewater control appear to offer 

gains in net economic welfare relative to baseline 

control levels. 

o Other control options for process vents and wastewater 

emission points may or may not add to these net 

economic welfare gains. 

21