# Section 211(B) Tier 2 High End Exposure Study of Conventional

and Oxygenated Gasoline

FINAL REPORT

Prepared for

AMERICAN PETROLEUM INSTITUTE

1220 L Street

Washington, DC 20005-4070

Prepared by

Barbara Zielinska, Eric M. Fujita, John C. Sagebiel, and David E. Campbell

Division of Atmospheric Sciences

Desert Research Institute

Nevada System of Higher Education

2215 Raggio Parkway

Reno, NV 89512

March 25, 2009

2215 Raggio Parkway, Reno, Ne vada 89512-1095 (775) 673-7300

# ACKNOWLEDGMENTS

We wish to acknowledge the financial suppor t for this study by the American Petroleum

Institute and Drs. Will Ollison and Lorraine Twer dok of the API for their administrative support

and technical guidance. We also thank the AP I review committee and the staff of the U.S.

Environmental Protection Agency for reviewing the draft exposure protocols and interim project

results. We also acknowledge th e vehicle testing performed duri ng the control experiments in

San Antonio by Lawrence Smith and Patrick Me rritt at Southwest Research Institute and

evaluation of potential biomarkers during the initial pilot study by Dr. Jacob McDonald of the

Lovelace Respiratory Research In stitute. We also acknowledge the assistance of Ted Johnson of

TRJ Environmental, Inc. for his input on the candidate microenvironments and review of our

draft exposure protocols. We al so acknowledge the following DRI personnel for their assistance:

Larry Sheetz for modifications to the sampling platforms; Aaron Centri c, Diana Ceballos and

Mark McDaniel for field sampling; Diana Ceba llos for evaluation of the SPME method; and

Katarzyna Rempala and Michael Keith for the organic speciation analysis.

ii

# TABLE OF CONTENTS

Page

Acknowledgments................................................................................................................ ........... ii

EXECUTIVE SUMMARY .............................................................................................................1

1. Quantification of Personal Exposures to Motor Vehicle Emissions in High Exposure

Microenvironments in Atlanta, Houston, and Chicago during Summer and Winter. ............ 1-1

1.1 Introduction ................................................................................................................... 1-1

1.2 Experimental .................................................................................................................. 1-2

1.2.1 Selection of Microenvironments .......................................................................... 1-2

1.2.2 Monitoring Methods ............................................................................................ 1-4

1.2.3 Exposure Biomarkers ........................................................................................... 1-5

1.3 Results and Discussion .................................................................................................. 1-6

1.3.1 Variation of day-to-day e xposures by ME in each city ....................................... 1-6

1.3.2 Distribution of exposures within MEs in each city (1-minute time series) ....... 1-19

1.3.3 Oxygenated and conventional gasoli ne (difference between cities) .................. 1-31

1.3.4 Effect of meteorology on exposure .................................................................... 1-35

1.3.5 Comparison of summer and winter exposures ................................................... 1-37

1.3.6 Correlations to breath concentrations ................................................................ 1-41

1.4 Conclusions ................................................................................................................. 1-45

1.5 References ................................................................................................................... 1-46

2. Relative Contributions of Vehicle Ev aporative and Exhaust Emission to

Concentrations of Volatile Air Toxics in High Exposure Microenvironments in

Houston

............................................................................................................................... ... 2-1

2.1 Introduction ................................................................................................................... 2-1

2.2 Experimental Approach ................................................................................................. 2-2

2.3 Results ..................................................................................................................... 2-3

2.4 Conclusions ................................................................................................................... 2-4

2.5 References ................................................................................................................... 2-10

3. Determination of the Quantitative Relati onships between Levels of Volatile Air

Toxics and Carbon Monoxide Measured In High End Microenvironments and At

Nearby Air Quality Monitoring Stations ............................................................................... 3-1

3.1 Introduction ................................................................................................................... 3-1

3.2 Experimental .................................................................................................................. 3-2

3.3 Results and Discussion .................................................................................................. 3-3

3.4 Conclusions ................................................................................................................... 3-4

3.5 References ..................................................................................................................... 3-4

4. Relationships of Attached Garage and Ho me Exposures to Fuel Type and Emission

Levels of Garage Sources ...................................................................................................... 4-1

4.1 Introduction ................................................................................................................... 4-1

4.2 Experimental .................................................................................................................. 4-1

iii

# 4.2.1 Vehicles and Vehicle Test Methods .................................................................... 4-1

4.2.2 Fuel Testing ......................................................................................................... 4-2

4.2.3 Test House ........................................................................................................... 4-2

4.3 Results ..................................................................................................................... 4-4

4.3.1 Fuel Analyses ....................................................................................................... 4-4

4.3.2 Vehicle Regulated and Hot Soak Emissions ........................................................ 4-5

4.3.3 Garage and Kitchen Exhaust/Eva porative Fuel Component Levels .................... 4-7

4.3.3.1 Background and Overall Concentrations .............................................. 4-7

4.3.3.2 Seasonal Impacts ................................................................................... 4-8

4.3.3.3 Fuel and Vehicle Effects ....................................................................... 4-9

4.3.3.4 Comparison with Emissions Data ....................................................... 4-16

4.3.3.5 Relationships of Garage and Kitchen Concentrations ........................4-19

4.4 Discussion ................................................................................................................... 4-21

5. Effect of Ventilation, Proximity, and Em ission Levels on In-Cabin Exposures of

Trailing Vehicle. .................................................................................................................... 5-1

5.1 Introduction ................................................................................................................... 5-1

5.2 Experimental .................................................................................................................. 5-1

5.2.1 Fuel Testing ......................................................................................................... 5-2

5.2.2 Relationship between Exhaust Emissi on Rates and In-Cabin Exposure -

Trailing Vehicle Test ................................................................................... 5-2

5.2.2.1 Test Protocol ......................................................................................... 5-2

5.3 Results ..................................................................................................................... 5-6

5.3.1 Background and Overall Concentrations ............................................................. 5-6

5.3.2 Vehicle and Fuel Effects .................................................................................... 5-12

5.3.3 Trailing Vehicle Effects ..................................................................................... 5-14

5.3.4 Comparison with FTP Data ............................................................................... 5-16

5.4 Discussion ................................................................................................................... 5-18

APPENDIX A..................................................................................................................................1

APPENDIX B ..................................................................................................................................1

APPENDIX C ..................................................................................................................................1

APPENDIX D..................................................................................................................................1

APPENDIX E ..................................................................................................................................1

APPENDIX F

............................................................................................................................... ....1

APPENDIX G..................................................................................................................................1

APPENDIX H..................................................................................................................................1

APPENDIX I ...................................................................................................................................1

iv

# LIST OF FIGURES

Page

Figure E-1. Distribution of r econstructed 1-min BTEX expo sures in high-end Atlanta

MEs. Edges of the box = first and third qua rtiles; black line = median; red line =

average. Minimum and maximum values (ppbv) are shown at the bottom and top

of the plots. Whisker covers 99.3% of the data distributi on. Filled circles > 3

times the box interval, empty ci rcle are within th at interval. The y-axis represents

the percentage of data distribution. ................................................................................ES-9

Figure E-2A. Comparison of average concentr ations of benzene, 1,3-BD, HCHO and CO

in three cities in Summer .............................................................................................ES-10

Figure E-2B. Comparison of average concentr ations of benzene, 1,3-BD, HCHO and CO

in three cities in Winter ................................................................................................ES-11

Figure E-3. MTBE/benzene ratio and contribution of evaporative emissions in Houston

MEs..............................................................................................................................E S-13

Figure E-4. Mean ratios of ME concentrations to correspond ing hourly measurements at

the regional air monitori ng station in Houston. ...........................................................ES-14

Figure E-6. The effect of fuel and vehicle op eration mode (i.e. normal or malfunction) on

observed concentrations in the kitchen ........................................................................ES-17

Figure 1.3.1-1. Time-integrated exposure levels in different MEs in Atlanta, Summer

2002 and 2003 ................................................................................................................ 1-13

Figure 1.3.1-2. Time-integrated exposure levels in different MEs in Atlanta, Winter 2004 ..... 1-14

Figure 1.3.1-3. Time-integrated exposure leve ls in different MEs in Chicago, Summer

2003

............................................................................................................................... . 1-15

Figure 1.3.1-4. Time-integrated exposure leve ls in different MEs in Chicago, Winter

2004

............................................................................................................................... . 1-16

Figure 1.3.1-5. Time-integrated exposure leve ls in different MEs in Houston, Summer

2004

............................................................................................................................... . 1-17

Figure 1.3.1-6. Time-integrated exposure leve ls in different MEs in Houston, Winter

2005

............................................................................................................................... . 1-18

Figure 1.3.2-1. 1-Minute time series for in -cabin exposures: ME1 (congested freeway),

ME2 (urban canyon); ME4 (underground garage) and ME5 (toll plaza) ...................... 1-27

Figure 1.3.2-2. 1-Minute time series fo r in-cabin exposures : ME6 (tunnel); ME13

(following high-emitting vehicle); ME3 (in-cabin refueling) and out-of-cabin

refueling, ME7 ............................................................................................................... 1-28

Figure 1.3.2-3. 1-Minute time series for out -of cabin outdoor exposures:ME8 (sidewalk);

ME10 (surface parking); ME11 (underg round garage) and ME12 (toll plaza) ............. 1-29

Figure 1.3.2-4. Correlations between 5-minut e canister samples and surrogate 1-minute

values, averaged over corresponding 5 minutes. ........................................................... 1-30

v

# Figure 1.3.3-1. MTBE and EtOH concentr ations in Houston and Chicago,

respectively..Note different y-axis scales for Chicago Sumer and Winter .................... 1-32

Figure 1.3.3-2. Comparison of benzene, 1,3-BD , HCHO, and CO average concentrations

in three cities in Summer ............................................................................................... 1-33

Figure 1.3.3-3. Comparison of benzene, 1,3-BD , HCHO, and CO average concentrations

in three cities in Winter .................................................................................................. 1-34

Figure 1.3.5-1. Time integrated average exposur e levels in different MEs in Atlanta in

Summer and Winter season. .......................................................................................... 1-38

Figure 1.3.5-2. Time integrated average exposur e levels in different MEs in Chicago in

Summer and Winter season ........................................................................................... 1-39

Figure 1.3.5-3. Time integrated average exposur e levels in different MEs in Houston in

Summer and Winter season ........................................................................................... 1-40

Figure 1.3.6-1. Average breath BTEX, 1,3-BD, MT BE, EtOH, and CO2 concentrations in

three cities in Summer ................................................................................................... 1-42

Figure 1.3.6-2. Average breath BTEX, 1,3-BD, MT BE, EtOH, and CO2 concentrations in

three cities in Winter ...................................................................................................... 1-43

Figure 1.3.6-3. Correlations between 1-minute surrogate benzene and 1,3-BD max values

and post-exposure breath concentrations (upper panel) and comparison of these

concentrations in different ME and cities (lower panel) ................................................ 1-44

Figure 2-1.Fractional contributi ons of evaporative emissions to total motor vehicles

emissions in Houston by ME. .......................................................................................... 2-9

Figure 3.1a. Location of ME sampling and fixe d monitoring stations in Chicago Metro

Area.

............................................................................................................................... .. 3-9

Figure 3.1b. Location of ME sampling and fixe d monitoring stations in Houston Metro

Area.

............................................................................................................................... 3-10

Figure 3-2a. Comparison of average versus the maximum 1-minute benzene levels by

city, season and microenvironment. ............................................................................... 3-12

Figure 3-2b. Comparison of average versus the maximum 1-minute 1,3-butadiene levels

by city, season and microenvironment. .......................................................................... 3-13

Figure 3-2c. Comparison of average versus the maximum 1-minute formaldehyde levels

by city, season and microenvironment. .......................................................................... 3-14

Figure 4.3-1. Effect of fuel and mode on observed concentrations in the garage. The

legend “N” is normal and “F” is malfunction. The 1,3-BD value for Houston-F is

suspect. ........................................................................................................................... 4-10

Figure 4.3-2. Effect of fuel and mode on observed concentrations in the kitchen. The

legend “N” is normal and “F” is malfunction. The 1,3-BD value for Houston-F is

suspect. ........................................................................................................................... 4-11

vi

# Figure 4.3-3. Effect of fuel and mode on observed sedan gara ge levels. The legend “N” is

normal and “F” is malfunction. The 1,3-BD level for Houston-F is suspect, see

text.

............................................................................................................................... .. 4-12

Figure 4.3-4. Effect of fuel and mode on observed truck gara ge levels. The legend “N” is

normal and “F” is malfunction. The 1,3-BD level for Houston-F is suspect, see

text.

............................................................................................................................... .. 4-12

Figure 4.3-5. Concentrations of 1,3-butadiene , MTBE and BTEX and CO as measured

from canisters in the garage and the adjacent kitchen in Summer 2002 ........................ 4-14

Figure 4.3-6. Concentrations of 1,3-butadie ne, MTBE and BTEX (A) and CO (B) as

measured from canisters in the garage and the adjacent kitchen in Winter 2005.

M=sample missing or invalid. ....................................................................................... 4-15

Figure 4.3-7. Comparison of SHED results wi th the observed caniste r concentration in

the garage for benzene. .................................................................................................. 4-16

Figure 4.3-8. Comparison of the SHED re sults with the observed SPME hot soak

concentration in the garage for benzen e A: all data, B: two outliers removed. ............. 4-16

Figure 4.3-9. Comparison of FT P Bag 1 emissions and observe d garage levels of 1,3-BD. .... 4-17

Figure 4.3-10. Comparison of FTP Bag 1 benzen e emissions and observed garage levels. ..... 4-18

Figure 4.3-11. Comparison of hot soak FT P Bag 1 benzene emissions and observed

SPME garage values. ..................................................................................................... 4-18

Figure 4.3-12. Comparison of garage and kitche n concentrations for 1,3-BD. A – all data,

B- with two outlier s removed (see text). ........................................................................ 4-19

Figure 4.3-13. Comparison of garage and k itchen concentrations of carbon monoxide. .......... 4-20

Figure 4.3-14. Comparison of garage and kitchen concentrations of benzene. ......................... 4-20

Figure 5.2-1. Map of Driving Test Location n ear San Antonio. The bl ue markers indicate

the location of the driving tests. ....................................................................................... 5-4

Figure 5.2-2. Map of Driving Test Location near Moore, TX. ................................................... 5-5

Figure 5.2-3. Elevation Profile of the Driving Route near Moore, TX. ..................................... 5-5

Figure 5.3-1. Comparison of Summer and Wi nter Background Concentrations with

Standard Deviations. HCHO is divided by 10 for scale. ................................................. 5-7

Figure 5-3-2. Concentrations of 1,3-BD, MTBE and BTEX (A) and CO (B) as measured

in the cabin of the trailing vehicle, Summer 2002 ........................................................... 5-8

Figure 5-3-3. Concentrations of 1,3-BD, MTBE and BTEX and CO as measured in the

cabin of the trailing vehicle, Winter 2005 ....................................................................... 5-9

Figure 5.3-4. Comparison of Summer and Winter Concentrations for the Trailing tests. ......... 5-10

Figure 5.3-5. Comparison of Summe r Background and Test Values. ....................................... 5-11

Figure 5.3-6. Comparison of Wint er Background and Test Values. ......................................... 5-11

vii

# Figure 5.3-7. Scatter plot of Normal Emitter and High Emitter Mean In-cabin Values for

all species except HCHO and EtOH. ............................................................................. 5-13

Figure 5.3-8. Time Series of In-Cabin (PID1) and Outside (PID2) PID Values. ...................... 5-15

Figure 5.3-9. Comparison of FTP Bag 2 Benzene Emissions to In-cabin Concentration in

the Trailing Vehicle. ...................................................................................................... 5-16

Figure 5.3-10. Comparison of FTP Bag 2 MTBE em issions to in-cabin concentrations in

the trailing vehicle. ......................................................................................................... 5-17

Figure 5.3-11. Comparison of FT P Bag 2 1,3-BD Emissions to In-cabin Concentrations

in the Trailing Vehicle. .................................................................................................. 5-17

viii

# LIST OF TABLES

Page

Table E-1. Measurement methods used in th e Section 211(B) Tier 2 High-End Exposure

Screening Study. Data applications for specific methods are classified as

reference, confirmatory, and surrogate. ...............................................................................3

Table E-2. The effects of changing vehicle, fuel and operational mode (i.e. normal or

malfunction) on observed concentrati ons in the trailing vehicle cabin. ............................17

Table 1.2.1-1. Microenvironmental Sampling. ............................................................................ 1-3

Table 1.3.1-1. Summer average, maximum, a nd minimum ME concentrations (ppbv) of

BTEX, 1,3-BD, HCHO, CH3CHO, EtOH, MTBE, and CO (ppmv) .............................. 1-7

Table 1.3.2-1A. Correlation coefficients (R 2 

# ) and associated statistic for relationships of

time-integrated measurements with c ontinuous methods (NMVOC and CO) for 3

cities, without ME3 and ME7 ........................................................................................ 1-21

Table 1.3.2-1B. Correlation coefficients (R 2 

# ) and associated statistic for relationships of

time-integrated measurements with c ontinuous methods (NMVOC and CO) for

ME3 and ME7 in 3 cities ............................................................................................... 1-22

Table 1.3.2-2. Summary of the reconstr ucted 1-minute data (ppbv), Summer ......................... 1-23

Table 1.3.2-3. Summary of the reconstr ucted 1-min data (ppbv), Winter ................................. 1-24

Table 1.3.2-4. Summary of the 5- minute canister data (ppbv) .................................................. 1-25

Table 1.3.4-1. Average, minimum, and ma ximum ambient temperatures and RH ................... 1-35

Table 2-1. Conventional gasoline versus re formulated gasoline RFG (from EPA OMS

web page http://www.epa.gov/OMSWWW/rf gnew.htm, updated by S. Romanow,

OMS).

............................................................................................................................... 2-5

Table 2-2. Summary of sample collections in urban MEs ........................................................... 2-6

Table 2-3. Mass ratios of MTBE to benzene in Houston by ME. ............................................... 2-7

Table 2-4. Mass ratios of MTBE to benzene in vehicle exhaust, gasoline vapor and liquid

gasoline. ........................................................................................................................... 2-8

Table 2-5. Fractional contributi ons of evaporative emissions to total motor vehicles

emissions in Houston by ME. .......................................................................................... 2-9

Table 3-1. Summary of sample colle ctions in urban microenvironments ................................... 3-5

Table 3-2. Average and standard deviation in ratios of the time-integrated CO from

canister samples to the corresponding hourly CO from regional ambient air

monitoring sites for Houston, Atlanta and Chicago by season and

microenvironment. ........................................................................................................... 3-6

Table 3-3. Average and standard deviations in ratios of BTEX and 1,3-BD from timeintegrated canister samples to the corre sponding hourly automa ted GC data from

the ambient air monitoring sites in Houston. ................................................................... 3-7

ix

# Table 3-4. Houston benzene ME/ambient ra tio comparison with HAPEM benzene ME

factors

............................................................................................................................... 3-8

Table 4.2-1. Summary of vehicles used. ...................................................................................... 4-2

Table 4.2-2. Protocol for atta ched garage experiments. .............................................................. 4-3

Table 4.3-1. Summary of propert ies for the six test fuels. ........................................................... 4-5

Table 4.3-2. Regulated and Hot Soak Em issions from the Ford F-150, Summer 2002. ............. 4-6

Table 4.3-3. Regulated and Hot Soak Emi ssions from the Ford F-150, Winter 2005. ................ 4-6

Table 4.3-4. Regulated and Hot Soak Emissi ons from the Toyota Camry, Summer 2002 ......... 4-6

Table 4.3-5. Regulated and Hot Soak Emissi ons from the Toyota Camry, Winter 2005 ............ 4-6

Table 4.3-6. Summary of Backgr ound Concentrations in Kitchen and Garage. Units are

ppbv, except as noted. ...................................................................................................... 4-7

Table 4.3-7. Summary of Test Concentration Ranges in Ki tchen and Garage. Units are

ppbv, except as noted. ...................................................................................................... 4-8

Table 4.3-8. Seasonal Impact on Observed Ma ximum Concentrations (Units are ppbv,

except as noted). ............................................................................................................... 4-8

Table 4.3-9. Seasonal Impact on Observed Ma ximum Concentrations (Units are ppbv,

except as noted), Normal Mode Vehicles Only. .............................................................. 4-8

Table 4.3-10. Seasonal Impact on Observed Average Concentrations (Units are ppbv,

except as noted), Normal Mode Vehicles Only. .............................................................. 4-8

Table 4.3-11. Effect of Fuel and Operational Mode of the Sedan on Observed Levels in

the Kitchen and Garage (Un its are ppbv, except as noted). ............................................. 4-9

Table 4.3-12. Effect of Fuel and Operational Mode of the Truck on Observed Levels in

the Kitchen and Garage (Un its are ppbv, except as noted). ............................................. 4-9

Table 5.2-1. Protocol for Trailing Vehicle Tests ......................................................................... 5-3

Table 5.3-1. Summary of Summer and Winter Ba ckground Concentrations. ............................. 5-6

Table 5.3-2. Summary of Test C oncentrations for Su mmer, Winter and Overall. Units are

ppbv, except CO as noted. ............................................................................................... 5-7

Table 5.3-3. Summary of Concen trations Observed During Idle Tests. Units are ppbv

except CO as noted. ....................................................................................................... 5-12

Table 5.3.4. Effect of Vehicle, Fuel, and Operational Mode. Units are ppbv, except CO as

noted. Number of measurements = n ............................................................................. 5-13

Table 5.3-5. Influence of high emitting vehicles and each fuel on traili ng vehicle in-cabin

concentrations. Units are ppbv except CO as noted. ..................................................... 5-14

Table 5.3-6. Summary of Seasonal Differences in the High Emitter Samples. ......................... 5-14

Table 5.3-7. Comparison of High and Low In- cabin Ventilation Conditions, Winter 2005

only. Units are ppbv except CO as noted. ...................................................................... 5-15

x

# EXECUTIVE SUMMARY

This study evaluated the upper-end distribution of inhalation exposures to evaporative

and combustion emissions from conventional and oxygenated-gasoline. This final report

describes the measurement methods and prot ocol used in the st udy and summarizes the

validation and initial analysis of the assembled database. The main findings and conclusions are

emphasized in this final report and additional details and descriptions of the data are provided in

several supporting appendices.

Introduction and Background

The 211b Research Group is an unincorporated group of USA fuel and fuel additive

manufacturers affiliated by contractual obligation to meet the testing requirements of Section

211(b) (2) and 211(e) of Clean Air Act. The Am erican Petroleum Institute (API) manages the

required work on behalf of the 211b Research Group.

Mobile source air toxics (MSAT) may pose an adverse health risk, especially in

microenvironments with high exposures to vehi cle exhaust or evaporative emissions. Although

programs such as reformulated gasoline (RFG) ar e intended to reduce the emissions of MSAT

and ozone precursors, uncertainties remain rega rding population exposures associated with both

oxygenate-gasoline blends and c onventional gasoline. Accordingl y, the EPA issued requirements

for a test program in accordance with the Altern ative Tier 2 provisions of the fuels and fuel

additives (F/FA) regulations, which are required pursuant to Section 211 of the Clean Air Act.

To satisfy those testing requirements, API contra cted with a research team consisting of the

Desert Research Institute (DRI), Southwest Re search Institute (SwRI), Lovelace Respiratory

Research Institute (LRRI), and TRJ Environmenta l, Inc (TRJ) to conduct a study of the high-end

distribution of inhalation expos ures to evaporative and combus tion emissions of conventional

and oxygenated-gasoline (MTBE-gaso line, and ethanol-gasoline).

The results of this study provide data that will allow estimation of the upper-end of the

frequency of annual average inhalation exposures to evaporative and combustion emissions of

gasoline and oxygenated-gasoline. EPA may accomplis h this by using the scripted exposures in

high-end microenvironments with EPA regulatory exposure models, such as the Hazardous Air

Pollutant Exposure Model (HAPEM). HAPEM is a screening-level exposure model for assessing

average long-term inhalation exposure of th e general population, or specific sub-populations,

over spatial scales ranging from urban to nati onal. The information from this study will permit

sensitivity analyses to determine the range of th ese exposures, especially during heavy traffic, in

residential and public parking garages and durin g refueling. The study also provides data for

determining the relative proportion of evapor ative versus combustion emissions in higher

exposure microenvironments.

The specific objectives of the study are to provide information allowing EPA to:

• Quantify personal exposures to motor vehi cle gasoline evapora tive and combustion

emissions in microenvironments (MEs) re presenting the upper end of the population

exposure frequency distribution (99 th 

# + percentile) of such exposures;

ES-1

# ES-2 • Determine quantitative relationships between personal exposures in selected MEs and

fixed site measurements in these MEs and at nearby air monitoring stations;

• Determine how personal exposures differ among cities and seasons in which methyl tbutyl ether (MTBE)- and ethanol (EtOH)-gasolines are used compared with a city where

oxygenated fuels are not used.;

• Extrapolate study data to other cities and other oxygenated fuels;

• Apportion the relative contribu tions of vehicle fuel combustion versus evaporative

emissions to personal exposures in high-end MEs;

• Determine the relationship between vehicl e tailpipe and evaporative emissions and

exposure levels in a trailing vehicle cabin a nd in a residence with an attached garage.

Experimental Methods and Approach

The study was conducted in several phases. Fi rst, DRI evaluated the suitability of

available measurement methods for meeting the t echnical objectives of the study. These methods

included continuous and time-integrated measurem ents of carbon monoxide (CO), total volatile

organic compounds (VOC), and the following MSAT species: benzene, toluene, ethylbenzene

and xylenes (BTEX), 1,3-butadiene (1,3-BD), methyl tertiary but yl ether (MTBE), formaldehyde

and acetaldehyde. Exposure measurements include d well-established time-integrated methods

for measurements of hydrocarbons and carbonyl compounds. These samples provide data of

known precision and accuracy for each chemical species of interest during each exposure

measurement, which typically covered a 20 to 40 min period. Several continuous and semicontinuous methods were used to provide time -resolved data ranging from 1 to 10 minutes.

Continuous exposure measurements included ben zene, toluene, ethylbenzene, and xylenes

(BTEX) by a portable mass spectrometer (M S), carbon monoxide (CO) by a portable

electrochemical analyzer and by a nondispersive infrared (NDIR) an alyzer, and estimates of total

volatile organic compounds by a portable photo ionization detector (P ID). Semi-continuous

measurements of BTEX were also obtained from analysis of solid phase microextraction (SPME)

fibers.

Because exposure levels in most microenvironm ents were expected to vary with time, the

measurement protocol included continuous measurem ents of target specie s with time resolution

of 1 minute or less. This requirement necessita ted the use of instrume nts such as the Kore

MS200 and the Alpha Omega formaldehyde analyzer , which have not previously been proven

for such application and did not perform suffici ently well in field conditions during the pilot

studies. Furthermore, there are no acceptabl e continuous methods for 1,3-butadiene, MTBE,

ethanol, acetaldehyde or nonmeth ane hydrocarbons (NMHC) that could be used in portable

modes of operation with adequate sensitivity. Th erefore, our sampling strategy consists of a

three-tier approach shown in Table E-1, which lists the overlapping measurement methods used

in the Section 211(B) Tier 2 High-End Exposure Screening Study and their intended application.ES-3Table E-1. Measurement methods used inthe Section 211(B) Tier 2 High-End Exposure Screening Study. Data applications forspecific methods are classified as reference, confirmatory, and surrogate.ContinuousSemi-ContIntegratedMethodT15 CONDIR COppbRAEMS200HCHOSPMECanisterDNPHAdsorbentApplicable Environmentsoutdoor andin-cabinalloutdoor andin-cabinhigher endMEsoutdoorAllallallallTime Resolution1 minsecondsseconds1 min1 min10 min20-40&5 min20-40 min20-40 minDetection Limits0.1 ppm0.04 ppm1 ppb1-3 ppbv1 ppbv0.2 ppbv0.05 ppbC0.1 ppbv0.2 ppbvData Application1SSSCCCRRRCO SC SCRSCPID2BTEXS (a)S (a)SC (c)CCR1,3-ButadieneS(a)S(a)S(c)RMTBES (a)S (a)S (c)CRFormaldehydeS (b)S (b)S (d)CRAcetaldehyeS(b)S(b)S(d)REthanolS(e)S(e)S(f)RNMHCS(a)S(a)S(c)R1. Category of data application include surrogate (S), confirmatory (C) reference (R), and surrogate compounds or signal (SC)2. Sum of molecules ionizable at 10.6 eV and detected by photoionization detector.S (a). Time series will be reconstructed from the canister/CO ratio for exhaust-dominated samples.S (b). Time series will be reconstructed from the DNPH/CO ratiofor exhaust-dominated samples except outdoor daytime samples.S (c). Time series will be reconstructedfrom the canister/PID ratio for exhaust- or evap-dominated samples in outdoor MEs.S (d). Time series will be reconstructed from the DNPH/PID ratiofor exhaust-dominated samples except outdoor daytime samples.S (e). Time series will be reconstructed from the solid adsorbent/CO ratio for exhaust-dominated samples.S (f). Time series will be reconstructed from the solid adsorbent/PID ratio for exhaust and evap-dominated samples.

# The measurements are classified in one of three tiers: reference, surrogate, and

confirmatory. The base set or “reference” (R) m easurements consist of three well-established

time-integrated measurements. These include: canister sampling and analysis by gas

chromatography with flame ionization detec tion for CO, BTEX, 1,3-butadiene, MTBE, and

nonmethane hydrocarbons (NMHC); 2,4-dinitrophe nylhydrazine (DNPH) cartridge sampling and

analysis by high performance liquid chromatogr aphy with UV detection for formaldehyde and

acetaldehyde; and solid adsorbent sampling and an alysis of ethanol by gas chromatography with

mass spectrometry. These three methods combined meas ure all species of interest over the entire

sampling period within each microenvironmen t. Although these integrated methods do not

characterize peak exposures in microenvironments with highly varying exposure levels, they

serve several other purposes. They provide a ba sis for validating continuous and semi-continuous

data. They also provide a basis for deriving correlations between th e time-integrated values with

time averages of continuous data from the CO and PID instruments. Thus the continuous data

were used as “surrogates” (S) for reconstructi ng the time series of specific MSAT based on these

correlations. For example, data for BTEX, 1,3-butadiene

, and MTBE from the canister

measurements were correlated to continuous CO and PID data to reconstruct their time series in

exhaust-dominated environments. In a similar manner, the time series of formaldehyde was

reconstructed from the correlation of the inte grated DNPH samples with CO. Outdoor afternoon

samples were excluded due to potential contributions of carbonyl compounds formed from

atmospheric reactions of hydrocarbons. Table E-1 s hows other correlations that can be used in

this manner. Two pilot studies were conducted in Reno, NV to test the proposed measurement

methods under field conditions and to refine the exposure protocols. Two experimental

approaches were used in the main study.

Controlled Exposure Measurements in San Antonio

First, DRI and SwRI conducted exposure m easurements in San Antonio under controlled

conditions to establish quantitative relationshi ps between vehicle tail pipe and evaporative

emissions and exposure levels in two specific mi croenvironments, a trailing vehicle cabin and in

a residence with an attached garage. The two vehicles (2.2L 4-cylinder 1993 Toyota Camry and

a 5.0L V8 1995 Ford F150 Pickup truck) used in these controlled exposure experiments were

tested at the SwRI laboratory fo r FTP (Federal Test Procedure) exhaust and hot soak evaporative

emissions (Merritt, 2005). The tests were perf ormed with the vehicl es in normal and in

malfunction condition while operating on summer a nd winter grade fuels from Houston, Atlanta

and Chicago in summer 2002 and winter 2005. Meas ured FTP exhaust NMHC emission rates for

the sedan and truck averaged 0.21 and 0.31 g/mi, respectively, in normal mode. Both emission

rates are below the certified emission standards. The induced malfunctions raised NMHC

emission rates by a factor of 16.7 for the sedan to 3.58 g/mi and factor of 7.0 for the truck to 2.20

g/mi. Differences in NMHC emission rates among the three regional fuels were not significant.

The p values of the regression between Atlanta and Houston and Atlanta and Chicago fuels were

0.07 and 0.08, respectively for normal mode and 0.01 and 0.04, respectively for malfunction

mode. The percent relative standa rd deviations of the NMHC em ission rates for the sedan and

truck were 15% and 14%, respectively, in normal mode and 3% and 6%, respectively with the

induced malfunctions.

The two test vehicles in normal operation a nd with induced malfunction were used to

determine exposure in a cabin of a third vehicle wh ich trailed the test vehi cle. During each test,

the trailing vehicle was driven behind the test vehicle over a travel loop of several miles in a

ES-4

# rural area south of San Antonio. Measurements were made during the fi rst 10 minutes without

the test vehicle in order to established background exposure le vels. Each trailing vehicle run

included three scenarios (based on the proximity to the leading ve hicle: far, near, and passing)

for each low and high speed (30 mph and 60 mph) according to a prescribed schedule. Separate

integrated samples were collected for backgr ound and separate periods corresponding to the

driving and idle portions of each test for each fuel (i.e., Atlanta, Houston and Chicago) and

emission condition (i.e., normal and malfunction m ode). Data from the integrated reference

methods showed observable relati onships between exhaust emission rates and in-cabin exposures

in a trailing vehicle.

The same two test vehicles (with and wit hout malfunctions) were used to determine

indoor exposure in a home with an attached residential garage. The vehicles were parked in a

closed garage also containing a gasoline power ed lawnmower and gasoline storage container

filled with the test fuels, with in-garage and adjacent room monitoring conducted before, during

and after the vehicle cool-down period. Time-integrated caniste r and cartridge samples were

collected for each test (one in the garage and one in the adjacent room). A set of continuous and

semi-continuous measurements by serial 10 mi nute average solid phase micro-extraction

(SPME) sampling were made durin g test period of two hours.

Personal Exposures in Houston, Chicago and Atlanta

In the second approach, DRI measured pers onal exposures in sele cted MEs representing

the upper end of the frequency distribution of potential population exposures. The study was

conducted in Houston, TX, Chicago, IL and A tlanta, GA where MTBE-gasoline, ethanolgasoline and conventional gasoline are used, respectively. These cities also satisfy additional

requirements of the study for ongoing ambient air monitoring programs and geographic and

climatologic diversity among the three cities. Sampling was performed during winter and

summer and under conditions that were conducive to higher exposures within each ME (e.g.,

downwind, low wind speeds, rush hour traffic) . Continuous measurements included both NDIR

and electrochemical CO, two PIDs and in-cabin and fuel tank skin temperature. From 3 to 5

time-integrated canister and DNPH cartridge samples were collected for the following twelve

microenvironments;

• ME1-cabin exposure in congested freeway during commute,

• ME2-cabin exposure in urban canyon,

• ME3-cabin exposure during refueling,

• ME4-cabin exposure in underground garage,

• ME5-cabin exposure at toll plaza,

• ME6- cabin exposure in on-road tu nnel (Houston and Chicago only),

• ME7-outside exposure during refueling,

• ME8-outdoor exposure at busy street,

• ME9-outdoor exposure at bus stop,

• ME10-outdoor exposure at surface parking lot during and after event,

• ME11-outside exposure in underground gara ge, 12-outdoor exposure at toll plaza,

• ME13-cabin exposure following a high emitter (Atlanta only)

ES-5

# In addition, 5-minute integrated canister sa mples were collected for ME6, ME7, ME10, and

ME13 during peak exposures th at corresponded to collecti on of breath samples.

Exposure Protocol and Study Plan, and Study Schedule

The Exposure Protocol and Study Plan was de veloped and refined based upon results of

the pilot studies and initial field measur ements during summer 2002. The following chronology

describes the main stages in the st udy and development of the Study Plan.

• First Pilot Study. Prior to the main field studies, DRI and LRRI conducted a 5-day pilot

study in Reno, NV, during February 2002 to test alternative measurement approaches

under field conditions similar to those that we re encountered in the main study (Zielinska

et al., 2002c). DRI and LRRI also evaluated the stability of the designated VOC species

in breath and urine samples. Based upon th e result of this pilot study, the exposure

protocols and measurement methods, sampling and analytical proce dures were refined

and proposed in the June 13, 2002 Exposure Prot ocol and Study Plan (Zielinska et al.,

2002a).

• Summer 2002 Field Studies. The field measurements in San Antonio, Houston

, and

Atlanta were completed in adherence to the June 2002 protocol during summer 2002.

These data were presented in three separate re ports: Interim Data Re port (Zielinska et al.,

2002b), Summer 2002 Atlanta Field Study Report (Z ielinska et al., 2003a) and Summer

2002 San Antonio and Houston Fi eld Study Report (Zielinska et al., 2004a). The work in

Chicago in the summer of 2002 was post poned, pending further evaluation of the

measurement protocol and assessmen t of the data collected in 2002.

• Second Pilot Study. The second pilot study in Reno wa s conducted to refine the exposure

protocol and further evaluate the surrogate approach and SPME measurements (Zielinska

et al., 2003c). Several improvements were implemented in the mobile sampling platform

during this time. Additional changes were inco rporated into the final version of Exposure

Protocol and Study Plan (Zie linska et al., 2003d) based upon discussions between EPA

and DRI on the results of these reports. Th e final study protocol approved by the U.S.

EPA is included in the Appendix A of this Final Report.

• The final version of the prot ocol was applied to the summ er 2003 and winter 2004/5 field

study in Atlanta, Chicago and Houston and in the winter 2005 in San Antonio. A data

report was previously prepared for the summer 2003 field study in Atlanta and Chicago

(Zielinska et al. 2004b).

API Section 211(B) Tier-2 Exposure Database

The data have been organized into four data files (API Data_Continuous.xls, API

Data_SPME.xls, API Data_Time-integrated.xls and API Data_Reconstructed.xls) containing the

continuous, SPME, time-integrated and reconstructe d exposure data. All files include data fields

describing the sample collection conditions (e.g.; microenvironment, fuel type, test mode) as

well as data flags indicating probl ems with the analytical or sa mple collection methods. Tables

ES-6

# explaining the meaning of each data field are also included with each file. The files are supplied

in Excel workbook format for convenience, but ha ve been formatted to be compatible with

common database software (the value -99 is used for missing data points, and time is in hhmm

text format)

The time-integrated data contains speciati on results from canister, DNPH cartridge, and

TENAX adsorbent tubes, plus time-averaged valu es of pollutants and environmental parameters

that were measured continuously during the batc h sample collection periods. Within the timeintegrated data file there are 4 sub-categories that are presented separately due to the differing

number of experimental variables for each t ype: 1) microenvironment exposure measurements

from the three cities, 2) breath samples collect ed from subjects participating in 4 of the

microenvironments, 3) residence with attached ga rage, and 4) trailing ve hicle exposure tests.

The SPME data is assembled in essentially the same manner as the time-integrated data,

but contains only the BTEX hydro carbon compounds and uses some different sample descriptors

where necessary to identify which portion of each test the sample was collected. The same

sample IDs are used to facilitate comparison of the two sampling methods.

The third data file contains 1-minute aver ages of the pollutants and environmental

parameters that were measured continuously dur ing the microenvironment exposure tests in the 3

cities. Data were typically logged every 10 s econds during testing, but to reduce measurement

noise, make the data set more manageable, and reduce the effect of minor timing discrepancies

between instruments due to imperfect clock s ynchronization or differences in sample line

residence time, the data was time averaged by minut e. Each data record in this file has both a

time/date stamp and an identification code that relates it to the corresponding time-integrated

sample. Data flags are given to identify any miss ing or invalid data for each minute. Due to the

large size of this file, the various sample descri ptors have not been included but these can be

derived from the identification code as described in the included key.

The fourth data file contains 1-min recons tructed data for benzene, 1,3-butadiane and

formaldehyde based on PID and NDIR CO continuous data, as described in Chapter 1 of this

report. Both full time integrated canister and DNPH-carbonyl samples and 5-min canister

samples collected over a peak exposur e in selected MEs, are included.

Study Findings

Quantification of Personal Exposures to Motor Vehicle Emissions in High Exposure

Microenvironments in Atlanta, Houston and Ch icago during Summer and Winter (Chapter 1)

• Since different fuels were used in each of the tree cities, only combined effect of city/fuel

was examined in this study.

• Day-to-day variations in high-end (99 th 

# + percentile) ben zene, 1,3-butadiene,

formaldehyde, and CO concentrations in diffe rent MEs were substa ntial and independent

of city and season, probably re lated to the activity and emi ssion rates of sources in the

given MEs which differ from day to day.

ES-7

# ES-8 • With the exception of refueling, exposure le vels were generally lower in outdoor MEs

and higher in enclosed MEs.

• The 20-min average exposures to benzene during refueling ranged up to few hundred

ppbv and showed substantial day-to-day variability.

• In-cabin exposures during on-road vehicle operation were le ss variable than in-cabin

exposures in garages and toll plazas.

• Exposure levels of BTEX species were highes t in refueling MEs, which are dominated by

evaporative emissions whereas exposures to CO, formaldehyde, and 1,3-butadiene were

highest in cold-start dominated MEs.

• BTEX and 1,3-butadiene measured by the time-integrated canister method correlated

well with continuous PID and CO measur ements, respectively, in all MEs except

refueling. Correlation of formaldehyde with continuous CO was weak, probably due to

photochemical production of this compound.

• Continuous PID and CO (NDIR) data can be used to reconstruct 1-minute time series for

benzene and 1,3-BD, respectively, provided that the averaged continuous measurements

are above the detection lim its of the instruments (25 ppbv and 0.5 ppmv, respectively).

CO data can also be used to reconstr uct 1-minute formaldehyde data; however, less

reliably so due to poorer correlation between these species.

• Reconstructed 1-minute time-series data for benzene and 1,3-butadie ne, averaged over

five minutes, correlated well with the co rresponding 5-minute can ister samples after

excluding the Houston refueling ME data, which were distorted by high concentrations of

MTBE.

• The concentrations of benzene and 1,3-butadie ne measured in post peak exposure breath

samples closely tracked the correspondi ng microenvironmental 1-minute maximum

reconstructed surrogate values.

• Increases in concentrations of measured sp ecies occur in all breath samples that were

collected within a minute of a peak exposure. In Atlanta and Chica go, the highest breath

concentrations of BTEX and 1,3-BD were observed in ME7 (refueling) and ME11

(underground garage), respect ively. In Houston, high concen trations of MTBE were

measured in ME7.

Figure E-1 shows the distribution of reconstructe d 1-min BTEX concentrations in high-end MEs

in Atlanta in Summer. One-min time resolution re flects the high short-time peak concentrations

necessary to characterize 99 th 

# + percentile exposure. The Atlant a winter distribution as well as

Houston and Chicago MEs look very similar.

Figure E-2 A and B shows the comparison of 1,3 -butadiane, benzene, formaldehyde and CO

averaged concentrations in three cities in Summer and Winter, respectively.2.41329.214.29.840.025.87.397.65.89.424.3172.113.329.71.46510.11.358318.03.130417.50.6253.72.2245413.30.8585.12.6807.02.19814.160.1465152.45.84011.72.953311.9ME1 ME2 ME3 ME4 ME5 ME7 ME8 ME8_9 ME10 ME11 ME12 ME130204060801001202.41329.21.46510.11.358318.03.130417.50.6253.72.2245413.30.8585.12.6807.02.19814.160.1465152.45.84011.72.953311.9ME1 ME2 ME3 ME4 ME5 ME7 ME8 ME8_9 ME10 ME11 ME12 ME1302040608010012014.29.840.025.87.397.65.89.424.3172.113.329.72.41329.21.46510.11.358318.03.130417.50.6253.72.2245413.30.8585.12.6807.02.19814.160.1465152.45.84011.72.953311.9ME1 ME2 ME3 ME4 ME5 ME7 ME8 ME8_9 ME10 ME11 ME12 ME1302040608010012014.29.840.025.87.397.65.89.424.3172.113.329.71. In-Cabin Congested Freeway5. In-Cabin Toll Plaza10. Outdoor Surface Parking2. In-Cabin Urban Canyon7. Outdoor Refueling11. Outdoor Underground Garage3. In-Cabin Refueling8. Sidewalk12. Outdoor Toll Plaza4. In-Cabin Underground Garage 9. Sidewalk/Bus Stop13. FollowingHigh EmittersFigure E-1. Distribution of reconstructed 1-min BTEX exposures in high-end Atlanta MEs. Edges of the box = first and third quartiles;black line = median; red line = average.Minimum and maximum values (ppbv) are shown at the bottom and top of the plots. Whiskercovers 99.3% of the data distribution. Filled circles > 3 times the box interval, empty circle are within that interval. The y-axis representsthe percentage of data distribution.ES-9Benzene0204060801001201401 2 3 4 5 6 7 8 9 10 11 12 13ME

ppbvHoustonAtlantaChicago1,3-Butadiene02468101 2 3 4 5 6 7 8 9 10 11 12 13ME

ppbvHoustonAtlantaChicagoFormaldehyde051015202530351 2 3 4 5 6 7 8 9 10 11 12 13ME

ppbvHoustonAtlantaChicagoCO02468101214161 2 3 4 5 6 7 8 9 10 11 12 13ME

ppmHoustonAtlantaChicagoFigure E-2A. Comparison of average concentrations of benzene, 1,3-BD, HCHOand CO in three cities in SummerES-10Formaldehyde05101520251 2 3 4 5 6 7 8 9 10 11 12 13ME

ppbvHoustonAtlantaChicagoCO051015201 2 3 4 5 6 7 8 9 10 11 12 13ME

ppmHoustonAtlantaChicagoBenzene01020304050601 2 3 4 5 6 7 8 9 10 11 12 13M E

ppbvHoustonAtlantaChicago1,3-Butadiene0246810121 2 3 4 5 6 7 8 9 10 11 12 13M E

ppbvHoustonAtlantaChicagoES-11Figure E-2B. Comparison of average concentrations of benzene, 1,3-BD, HCHOand CO in three cities in Winter

# ES-12 Relative Contributions of Vehicle Evaporative and Exhaust Emissions to Concentrations of

Volatile Air Toxics in High Expos ure Microenvironments (Chapter 2)

• MTBE/benzene ratios were used to estimate the relative contributions of evaporative and

exhaust emissions to MSAT. This basis for this approach is that th e proportion of MTBE

in exhaust is reduced during combustion rela tive to its proportion in the fuel while

benzene is enriched in exhaust relative to its proportion in the fu el due to toluene and

xylene dealkylation. Consequently, MTBE to benzene ratios are subs tantially lower in

exhaust than in liquid fuel or headspace vapor s. Exposures at the two refueling MEs (3 &

7) were dominated by evaporative emissions as expected, with MTBE/benzene ratios in

Houston of 20 to 30. Ratios for all other MEs were between 1 and 4.

• The fractional contribution of evaporative and exhaust emission were estimated for each

ME based on exhaust MTBE/benzene ratios fr om several dynamometer exhaust tests and

on-road tunnel measurements and evaporat ive MTBE/benzene ratios for the SwRI SHED

tests and composition of gasoline headspace vapor. Exposures during refueling (ME3,

ME7) are 100% due to evaporative emissions w ithin the uncertainties associated with the

measurements and method. All other MEs ar e dominated by tailpipe emissions with

fractional evaporative contributions < 10%.

Figure E-3 shows the MTBE/benzene ratio and cont ribution of evaporative emissions in Houston

MEs

Quantitative Relationships Between Levels of Volatile Air Toxics and Carbon Monoxide

Measured in High-End Exposure Microenvironm ents and at Nearby Air Quality Monitoring

Stations (Chapter 3)

• MEs in close proximity to running vehicle engi nes have enhanced CO relative to ambient

levels at nearby air quality monitoring site s with enrichment ratios approaching 40 where

ventilation is limited, as in underground garage s. Average in-cabin CO/ambient ratios in

congested freeway traffic range from 2-9. ME locations less proximate to operating

vehicles, such as gas stations and urban sidewalks, have CO/ambient ratios of 0.5-2.

• The mean ratio of in-vehicle exposures on c ongested freeways (ME #1) to ambient levels

at a monitoring station of 9.8 ± 3.8 ratio for Houston exceed the HAPEM5 median

proximity factor of 4.9 (triangular dist ribution mode:range 1.9:0-14.3) and HAPEM4

proximity factor of 6.9 for this ME (R osenbaum, 2005; Long & Johnson, 2004), although

by less than expected.

Figure E-4 shows the mean ratios of ME concen trations to corresponding hourly measurements

at the regional air mon itoring station in Houston.Evaporative Emissions Contribution0.00.20.40.60.81.01 2 3 4 5 6 7 8 9 10 11 12ME

FractionsummerwinterMTBE/benzene0204060801 2 3 4 5 6 7 8 9 10 11 12ME

Ratiosummerwinter1. In-vehicle congested freeway 5. In-vehicle toll plaza9. Outdoor bus stop2. In-vehicle urban canyon 6. In-vehicle road tunnel10. Outdoor surface parking3. In-vehicle refueling7. Outdoor refueling11. Outdoor underground garage4. In-vehicle underground garage 8. Outdoor sidewalk12. Outdoor toll plazaFigure E-3. MTBE/benzene ratio and contributionof evaporative emissions in Houston MEsES-13Houston- Summer1101001000100001 2 3 4 5 6 7 8 9 10 11 12Microenvironment

ME/Station RatioBenzeneToluenem&p-XylenesHouston - Winter1101001000100001 2 3 4 5 6 7 8 9 10 11 12Microenvironment

ME/Station Ratio1. In-vehicle congested freeway 5. In-vehicle toll plaza9. Outdoor bus stop2. In-vehicle urban canyon 6. In-vehicle road tunnel10. Outdoor surface parking3. In-vehicle refueling7. Outdoor refueling11. Outdoor underground garage4. In-vehicle underground garage 8. Outdoor sidewalk12. Outdoor toll plazaES-14Figure E-4. Mean ratios of ME concentrations to corresponding hourly measurements at the regional air monitoring station in Houston.

# Relationship of Attached Garage and Home Exposures to Fuel Type and Emission Levels of

Garaged Sources (Chapter 4)

• Two target components, formaldehyde and et hanol, had high kitchen background values

indicating indoor sources of these compounds. Average kitchen formaldehyde levels

were higher in summer than winter, probabl y due to enhanced off-gassing of building

materials and/or penetration of ambient photochemical formaldehyde.

• Kitchen BTEX, MTBE and CO species are hi gher in winter than summer. The exception

is toluene which shows a minimal difference th at actually averages higher in summer for

normal mode vehicles. This is consistent w ith indoor toluene emissions from paints,

adhesives, cleaning, and personal care products.

• MTBE and ethanol are highest for fuels co ntaining those species, as anticipated.

• FTP exhaust and SHED evaporative emissions were tested for each vehicle, fuel, and

emissions mode, and compared to observed levels in the garage. Neither canister nor

SPME samples show strong (r 2 

# =0.003 and 0.005, respectively) correlations with hot soak

emissions, although cold-stabilized FTP Bag 2 benzene appears reasonably correlated

(r 2 

# = 0.4) to the cold-start SPME.

• Correlations of kitchen levels with garage concentrations were weak (r 2 

# generally below

0.1) and could not be used to predict kitchen exposures from garage levels.

Figure E-5 shows the effect of fu el and vehicle operational mode (i.e. normal or malfunction) on

observed concentrations of 1,3-butadiene, BTEX , MTBE, formaldehyde, et hanol and CO in the

kitchen.

Effect of Ventilation, Proximity, and Emission Le vels on In-Cabin Exposures of Trailing Vehicle

(Chapter 5)

• Summer and winter in-cabin values were similar in magn itude with the exception of

formaldehyde which was higher in the summ er, possibly due to higher photochemical

activity and higher temperatures that led to more off-gassing of formaldehyde in the

vehicle cabin interior.

• Trailing vehicle cabin values were larger than background va lues (as measured during the

first 10 min run without the test vehicle) except for formaldehyde which was actually

lower than background in winter tests.

• Idle test sample values were on average twice those encountered in driving tests,

suggesting that proximity and proximity dur ation may substantially impact in-cabin

trailing vehicle concentrations.

ES-15

# • Average in-cabin levels were affected by bot h state of maintenan ce of the vehicle and

fuel composition. Use of Atlanta fuel result ed in higher BTEX concentrations in the

trailing vehicle cabin, which is consistent with higher aromatic contents of Atlanta fuel,

especially in summer. Similarly BTEX con centrations were consistently higher during

the summer, which is also in concert with higher aromatic conten ts of summer fuels,

especially for Atlanta. Averaging over th e fuels and vehicles, the high emitter mode

resulted in 2.2 times higher in-cabin exposur e levels for the trailing vehicle than the

normal emitter mode except for HCHO which was relatively unchanged from

background.

• Trailing vehicle ventilation stat us affected in-cabin values; the concentrations observed

by continuous PID and CO monitors were more variable under high ventilation. This may

be rationalized as the vehicle moving into and out of the exhaust plume of the leading

vehicle with in-cabin values changing rapi dly under high ventilation; whereas under low

ventilation, in-cabin concentrations trapped as the vents were closed stayed relatively

constant during the remainder of low ventilation conditions.

• Trailing vehicle tests indicated that the larg est impact on in-cabin values came from the

emissions mode (normal or malfunc tion) of the leading vehicle.

Table E-2 shows the effects of changing vehicle, fuel and opera tional mode (i.e. normal or

malfunction) on observed concentrations of 1,3-butadiene, BTEX, MTBE, formaldehyde,

ethanol and CO in the trailing vehicle cabin.

ES-16

### 0 5 10 15 20 25 30 35 40 45 50

Budi13 Benze Tolue Etbz Mp_xyl O_xyl MTBE CO,ppm Formal EtOH



### compoundppbv Atlanta-N

Atlanta-F

Houston-N

Houston-F

Chicago-N

Chicago-F 

### 339,542



# Figure E-6. The effect of fuel and vehicle op eration mode (i.e. normal or malfunction) on

observed concentrations in the kitchen

Table E-2. The effects of changing vehicle, fuel and operational mode (i.e. normal or

malfunction) on observed concentrations in the trailing vehicle cabin.

Budi13 Benze Tolue Etbz Mp_xyl O_xyl MTBE CO, ppm Formal

Truck only 0.42 1.14 2.06 0.38 1.24 0.52 0.15 1.08 4.23

Car only 0.59 1.13 1.87 0.33 1.11 0.45 0.53 1.42 6.13

Atl fuel only 0.53 1.44 2.79 0.51 1.66 0.68 0.14 1.41 5.99

Hou fuel only 0.56 1.05 1.63 0.35 1.19 0.50 1.28 1.10 5.88

Chi fuel only 0.48 0.87 1.32 0.20 0.66 0.28 0.03 1.22 4.20

Normal only 0.06 0.46 1.05 0.21 0.73 0.31 0.16 0.41 5.21

High emitter only 1.01 1.85 2.92 0.52 1.64 0.67 0.56 2.18 5.35

St Dev high emitter only 26% 35% 40% 43% 43% 45% 199% 42% 55%



# ES-17

# Evaluation of Measurement Method’s Performance

The integrated canister and DNPH sampling methods produced nearly 100 percent data

capture of high quality data as confirmed by internal consistency checks. However, some

challenges were encountered in applying two co ntinuous confirmatory measurements, the Kore

MS200 and formaldehyde analyzers. In most of the MEs, the MS200 had vacuum problems,

most probably due to the high humidity in Hous ton, Chicago and Atlant a, and did not produce

useful data. The instrument performed much be tter during first and second Pilot Study in Reno,

probably because of much lower humidity. Although the formaldehyde analyzer was upgraded,

it still required extensive us er intervention and did not run reliably under the conditions

encountered. The sensitivity of the instrument to environmental noise associated with driving

limited its utility under mobile sampling. With pr oper operation and better characterization of

instrument performance, the supplemental con tinuous formaldehyde analyzer may prove useful

for ambient monitoring at fixed location.

The SPME also had excellent data capture, as did the continuous instruments for CO and

PID. The two PIDs were compared both in cont rolled tests and collocate d during the MEs. In

both cases, they tracked each other quite well. Differences appear to be due to an offset in one

unit, and a slightly different response sp eed between the two units. The NDIR CO and

electrochemical CO (Langan T15) instruments co mpared favorably, usually within 1 ppm. The

detailed description of data quality and QA/QC procedures are presented in Appendix H.

Conclusions

Exposure levels are directly re lated to the activity and emi ssion rates of sources in the

microenvironment and inversely re lated to the distance between sources of emissions and the

measurement location and extent of dilution of emissions, which are a function of meteorological

conditions and the presence of phys ical obstruction that inhibit dispersion. A ll of these factors

contribute to the large te mporal and spatial variations in po llutant exposures that exist within

each of the microenvironments. Testing at SwRI showed that the differences in exhaust and

evaporative emission rates among the three regional fuels were not statistical ly significant except

for MTBE. With the exception of MTBE, the sma ll differences due to fuel formulation are

masked by the large variations of exposure le vels within each of the microenvironments.

The information from control exposure expe riments in San Antonio provided useful

context for interpreting the varying exposures in the high-end microenvironments in Atlanta,

Houston and Chicago. We found that the result s of the trailing vehicle experiments were

qualitatively consistent with our observations in the three cities. In -cabin exposure levels even in

congested traffic were on the order of a factor of two higher than b ackground. Congested stopand-go conditions resulted in so me increase in exposure levels due to shorter gaps between

vehicles and highest on-road exposures were measured when following high emitters. In-cabin

exposures during low ventilation co nditions were relatively constant and retained the levels at

the time ventilation was cut off.

Evaporative emissions were the only substa ntial components of high-end ME exposures

during vehicle refueling operati ons, where they are dominant. Since refueling MEs had the

highest relative levels of these components, they constituted the peak exposures, although overall

the average population time spent in these high e nd MEs is likely the shortest. The contributions

ES-18

# of evaporative emissions for all other MEs were typically about 5% of the total measured

exposures. Results were similar for both seas ons, although evaporative contributions during

refueling were marginally less during summer, po ssibly due to more rapi d dispersion of vapors

and evaporation of fuel spilled during each refu eling test at higher summer temperatures. These

results suggest that the contem porary Houston vehicle fleet cont ained relatively few carbureted

or leaking vehicles given that evaporative emissions were nota substantial source in the nonrefueling MEs tested. Refueling emissions releas ed from pressurized fuel systems and spilled

fuels appeared to be the primary source of peak evaporative exposures. The lack of a seasonal

variability in the evaporative contribution was also consistent with this supposition. Although it

was not feasible to try to dis tinguish further between liquid and headspace vapor contributions by

the method used, the extremely low MTBE/benzen e ratios observed for the roadway, sidewalk,

and parking MEs strongly suggest that the impact from leaki ng liquid gasoline emissions were

minor.

HAPEM5 proximity factors may need to be adjusted since they were based on a 1998

scoping study where measurements ‘highlighted tr ailing behind heavy duty diesel vehicles and

diesel city buses when possible’. Houston ME/amb ient ratio comparisons also generally exceed

the other HAPEM factors. Refueling ratios (M E3, ME7) for benzene were higher than the

corresponding HAPEM f actors as expected, given the refueling protoc ol provisions maximizing

exposure discussed above and below. Concentrati ons of exhaust compounds such as CO and 1,3-

butadiene were enhanced under reduced ventilati on situations.

It must be recognized that the various micr oenvironments were sel ected with a goal to

capture the 99th percentile exposure levels within each type of microenvironment, as prescribed

by EPA and API. We also selected specific sa mpling times and locations with the greatest

potential for higher exposures. These selecti ons were based on considerations of various

emission surrogates such as traffi c counts, diurnal variations in average highway speeds, length

of queues at toll plazas, number of cars refue ling or entering and exiting parking garages.

Surrogates of dispersion included wind roses and diurnal variations in temperature.

Measurements in microenvironments with unres tricted dispersion were made in the early

morning or evening during calm conditions and minimal vertical mixing. In moderate wind

conditions, we drove parallel to the prevailing wind to reduce th e impact of cross winds. Thus,

the ranges of exposures determined in this study are skewed toward the higher end of the

distribution of exposures fo r each microenvironment.

References

Long, T. and T. Johnson (2004). Development of Penetration and Proximity Microenvironment

Factor Distributions for the HAPEM5 in S upport of the 1999 National-Scale Air Toxics

Assessment (NATA). Memorandum prepared by TRJ Environmental, Inc. for the U.S.

Environmental Protection Agency, Research Triangle Park, NC, April 5, 2004

Merritt, P. (2005). Evaporativ e and Tailpipe Emissions Suppor t for S211b Tier 2 Exposure

Study. Final report submitted by Southwest Re search Institute to Desert Research

Institute on July 29, 2005.

ES-19

# Rosenbaum, A. (2005). The HAPEM5 User’s Guide. Report prepared by ICF Consulting for the

U.S. Environmental Protection Agency, Research Triangle Park, NC, March 2005.

Zielinska, B., E. M. Fujita, J.C. Sagebiel, D. E. Campbell, L.R. Smith, T. Johnson (2002a).

Exposure Protocol and Study Plan for the Section 211 (B) Tier 2 High End Exposure

Screening Study of Baseline and Oxygenated Gasoline. Prepared for American Petroleum

Institute, 1220 L Street, Wa shington, DC 20005-4007. June 13, 2002

Zielinska, B., E. M. Fujita, J. C. Sagebiel, D. E. Campbell, J. McDonald (2002b). Interim Data

Report for Section 211 (B) Tier 2 High-End Exposure Screening Study of Baseline and

Oxygenated Gasoline. Prepared for Ameri can Petroleum Institute, 1220 L Street,

Washington, DC 20005-4007. November 15, 2002.

Zielinska, B, J. Sagebiel, E. Fujita, D. Campbe ll, J. McDonald, T.J. Kelly, and D. W. Joseph

(2002c). Section 211(B) Tier2 High-End Exposure Screening Study of Baseline and

Oxygenated Gasoline-Pilot Study. Prepared fo r American Petroleum Institute, 1220 L

Street, Washington, DC 20005-4007. June 13, 2002

Zielinska, B, E.M. Fujita, and J.C. Sagebiel (2003a). Section 211 (B) Tier 2 High End Exposure

Screening Study of Baseline and Oxygenated Gasoline-Summer 2002 Atlanta Field Study

on Baseline Gasoline. Prepared for Ameri can Petroleum Institute, 1220 L. Street,

Washington, DC 2005-4070. March 13, 2003.

Zielinska, B., J.C. Sagebiel, D. Campbell, D. Ceballos, M. McDaniel, and E.M. Fujita (2003b).

Section 211 (B) Tier 2 High End Exposure Sc reening Study of Baseline and Oxygenated

Gasoline-2nd Reno Pilot Study. Prepared for American Petroleum Institute, 1220 L

Street, Washington, DC 20005-4007. June 13, 2003

Zielinska, B., E. M. Fujita, J.C. Sagebiel, D. E. Campbell, L.R. Smith, T. Johnson (2003d).

Exposure Protocol and Study Plan for the Section 211 (B) Tier 2 High End Exposure

Screening Study of Baseline and Oxygenated Gasoline. Prepared for American Petroleum

Institute, 1220 L Street, Washington, DC 20005-4007. Final Version. October 1, 2003

Zielinska, B., J.C. Sagebiel, D. Campbell, E.M. Fujita (2004a). Section 211 (B) Tier 2 High End

Exposure Screening Study if Baseline a nd Oxygenated Gasoline-Summer 2002 San

Antonio and Houston Field Studies. Prepared for American Petroleum Institute, 1220 L.

Street, Washington, DC 2005-4070. March 5, 2004.

Zielinska, B., J.C. Sagebiel, D. Campbell, E.M. Fujita (2004b). Section 211 (B) Tier 2 High End

Exposure Screening Study if Baseline and Oxygenated Gasoline-Summer 2003 Chicago

and Atlanta Field Studies. Pr epared for American Petroleum Institute, 1220 L. Street,

Washington, DC 2005-4070. July 5, 2004.

ES-20

# 1. Quantification of Personal Exposures to Motor Vehicle Emissions in High

Exposure Microenvironments in Atla nta, Houston, and Chicago during

Summer and Winter.

1.1 Introduction

Gasoline-powered vehicles emit a portion of ozone-forming volatile organic compounds

(VOC) and mobile source air t oxics (MSAT) in the urban ar eas of the country. Elevated

exposures to gasoline-related MSAT have been reported in certain microenvironments (MEs),

such as in vehicle cabins during commuting on c ongested roadways (Batterman et al., 2002;

Chan et al. 1991; Rodes et al., 1998; Fedoruk and Kerger 2003; Weisel et al., 1992; Jo and Park,

1999), refueling (Vayghani and Weisel 1999; Vainitalo et al., 1999; Lindstrom and Pliel, 1996)

or in urban canyons (Rodes et al., 1998; Chan et al. 1991).

Although oxygenated fuel and reformulated gasoline (RFG) programs are intended to

reduce the emissions of ozone precursors and MSAT , uncertainties remain regarding the

population exposures associated with oxygenated and conventional gasoline. Accordingly, in

2001 EPA issued testing requirements under Alternat ive Tier 2 provisions of the fuel and fuel

additive (F/FA) health effects testing regulations, required purs uant to Section 211(b) of the

Clean Air Act.

The population exposure study reported here targets conventiona l gasoline and two

oxygenated blends containing methyl tertiary butyl ether (MTBE) and ethanol (EtOH) and

conducts studies in prospective high-end microe nvironments (MEs) likely associated with the

most-exposed populations. Personal exposures are quantified in selected MEs representing the

upper end of the frequency distribution of poten tial population exposures. The studies take place

in cities that have ongoing ambient air monitoring programs, located in hot and cold parts of the

country, using one of the three target fuels. Sampling was performed during winter and summer

seasons and under conditions (e.g., downwind, low wind speeds, rush hour traffic, fuel spillage,

trailing high emission vehicles) thought to maximize exposure within each ME. The same

sampling protocols (e.g., location, duration, cabin ventilation) were used in both seasons

whenever possible. A number of fuel emission and exhaust co mponents [carbon monoxide (CO),

carbon dioxide (CO 2 

# ), benzene, toluene, ethylbenzene, xylenes (BTEX), MTBE, 1,3-butadiene

(1,3-BD), EtOH, formaldehyde (HCHO), and acetaldehyde (CH 3 

# CHO)] were measured within

thirteen MEs in personal breathing zones, a nd in breath immediately after measured peak

exposures. The results of these microenvironmen tal studies were intended to include the upperend (99+ th 

# percentile) of the frequency of annual aver age inhalation exposures to evaporative and

combustion emissions from the three targeted ga solines. The study also estimates the relative

proportion of evaporative and combustion em issions by ME in breathing zone air.

1-1

# The specific objectives of the study are to provide information allowing EPA to:

• Quantify personal exposures to motor vehi cle gasoline evapora tive and combustion

emissions in MEs represen ting the upper end of the population exposure frequency

distribution (99+ th 

# centile) of such exposures;

• Determine quantitative relationships between personal exposures in selected MEs and

fixed site measurements in these MEs and at nearby air monitoring stations;

• Determine how personal exposures differ across seasons and cities us ing the three target

fuels (conventional-, MTBE-, and EtOH-gasoline);

• Extrapolate study data to other citi es and other oxyge nated fuels; and

• Apportion the relative contributi ons of vehicle fuel combustion vs. evaporative emissions

to personal exposures in high-end MEs.

1.2 Experimental

1.2.1 Selection of Microenvironments

Houston (TX), Chicago (IL) and Atlanta (GA) were selected as the study sites. These

cities have ongoing ambient monitoring progr ams and dispense MTBE-RFG, EtOH-RFG, and

conventional gasoline formulations, respectively. On e of the goals of the project was to sample

high-end MEs, plausibly char acterized in the upper 99+ th 

# percentile of exposures to

exhaust/evaporative emissions from gasoline- fueled vehicles. Selection of high-end MEs 1 

# was

made in consultation with EPA and independent peer reviewers according to the selection

criteria described in the Expos ure Protocol and Study Plan (Zielinska et al, 2003a) included in

Appendix A. Table 1.2.1-1 lists the MEs c hosen along with the number of replicate

measurements taken in each ME, whether biomarke r (breath) measurements were taken for that

ME, and the sampling time spent in each ME.

1 ME1 : In-cabin congested freeway; ME2 : In-cabin urban canyon; ME3 : In-cabin refueling; ME4 : In-cabin underground garage; ME5 : In-cabin

toll plaza; ME6 : In-cabin roadway tunnel; ME7 : Out-of-cabin refueling; ME8 :Out-of-cabin sidewalk; ME9 : Out-of-cabin sidewalk/bus stop;

ME10 : Out-of-cabin surface parking; ME11 : Out-of-cabin underground garage; ME12 : Outside toll plaza; ME13 : In-cabin trailing high-emitter

vehicle



# 1-2

# Table 1.2.1-1. Microenvironmental Sampling.

ME # ME Description Replica

tes Biomar

ker SamplingTime

(min)**

1 In-Cabin Congested Freeway 5 40 (20 H and 20 L)

2 In-Cabin Urban Canyon 3 40(20 H and 20 L)

3 In-Cabin Refueling 5 20 (10 H and 10 L)

4 In-Cabin Underground Garage 5 40 (20 H and 20 L)

5 In-Cabin Toll Plaza 3 40 (20 H and 20 L)

6* In-Cabin Roadway Tunnel 5 yes 40 (20 H and 20 L)

7 Out-of-Cabin Refueling 5 yes 20

8 Out-of-Cabin Sidewalk 3 40

8/9 Out-of-Cabin Sidewalk/Bus Stop 3 40

10 Out-of-Cabin Surface Parking 3 40

11 Out-of-Cabin Underground Garage 5 yes 40

12 Outdoor Toll Plaza 3 40

13* In-Cabin Trailing High-Emitting

Vehicles 5 yes 40 (20 H and 20 L)

*ME6 was sampled in Houston & Chicago and ME13 in Atlanta

** H refers to high ventilation and L to low ventilation conditions (see Monitoring

Methods below)

The ME number refers to the same type of ME in each city studied. Since ME6 refers to a

roadway tunnel and a suitable tunnel was not found in Atlanta, ME13 (following a high emitting

vehicle) was substituted.

Prior to selecting specific ME locations, Desert Resear ch Institute (DRI) personnel

surveyed potential high-end MEs in each city. The objectives of these surveys with portable gas

analyzers were to determine the suitability of candidate sampling locations with respect to

access, maximal exposure levels, and the variabil ity of these exposures. The sampling period in

each ME was selected to coincide with maximum activity level (i.e., emissions and exposure) as

described in the Protocol (Appe ndix A). In the absence of data on the range of actual emission

component exposures in various MEs in each city, we considered available surrogate parameters

for emission and dispersion to select locations and sampling periods with the greatest potential

for maximal exposures. These emission surrogates in cluded diurnal traffic c ounts, variations in

highway speeds, length of queues at toll plazas, concurrent numbers of cars refueling, and count

rates entering and exiting parki ng garages. Surrogates for disp ersion included diurnal wind roses

and variations in temperature. Where possible we drove parallel to the prevailing wind direction

to reduce the impact of cross winds and sample d downwind of the nearest emission sources. Our

sampling strategy also recognized that vehicle exhaust emission s are significantly higher for

identified high emitting vehicles and all vehicl es during cold starts (e.g., at parking lots,

underground garages, and service stations) a nd accelerations (e.g., at toll plazas, roadway

intersections). All of these factors are important in unders tanding the high-end perspective of

sampling and the temporal and spatial variati ons that exist within these high-end MEs.

1-3

# 1.2.2 Monitoring Methods

Instrumented Van

. All in-cabin and out-of-cabin expos ure measurements were performed

with the mobile sampling van, a 1996 Chrysl er Minivan, DRI-modifi ed for on-road and

stationary sampling. The power system included two banks of rechargeable AGM gel batteries

with minimal H 2 

# out-gassing during either charge or discharge. Each bank had a 1750 watt

inverter for 110v AC power and direct connections for 12v DC, giving maximum flexibility. The

suspension of the vehicle was upgraded to support the additional battery and instrument weight.

Seats were removed and replaced with an adjustable equipment racks. For refueling experiments,

a second fuel pump was installed to facilitate prompt removal of fuel. In-cabin and exterior

temperature and relative humidity sensors were installed along with an additional sensor

measuring fuel tank temperature. The data acqui sition system has eight analog-to-digital inputs

to record instrument outputs, which include a global positioning satellite (GPS) sensor, and

compiles spatially-located data into a single data base. All in-cabin equipment was manifolded to

sample from a point in the driv er's breathing zone. This manifold inlet could also be extended

outside for stationary sampling purposes (e.g., into the subject breathing zone during refueling

tests). Infiltration of outside air was adjusted by opening or closing windows in the front and rear

of the cabin and switching the he ating/AC system from vent to recirculate. In this manner two

ventilation modes, high (all open) and low (all closed), were in cluded in all in-cabin tests.

Equipment Cart. For sidewalk, bus stop and outdoor to ll plaza tests, sampling equipment

was placed on a cart that was pushed along the si dewalk of a busy street in an urban canyon

(ME8), patrolled a bus stop sidewa lk at a high traffic density inte rsection (ME9) or was stationed

next to a toll booth during rush hour traffic (M E12). Sampling inlets were positioned in the

subject breathing zone. Detailed protocols for sampling in ea ch ME are described in the

Exposure Protocol and Study Plan (Zielinska et al, 2003a), included in Appendix A.

Measurements in each ME were repeated three to five times for each city-season as noted in

Table 1.2.1-1.

Sampling and Analysis Methods. Three approaches were used to measure targeted

compounds in the high-end MEs: (1) reference method time-integrated samplers to quantify

concentrations over 20-40 minute sampling periods; (2) continuous surrogate method monitors to

determine short-term concentr ation variations over 10-60 se cond sampling periods; and (3)

supplemental methods to provide additional short-term surrogate concentration estimates over

intermediate time frames of several minutes. S upplemental methods included newer methods that

have not been fully adapted or ruggedized fo r field use. The supplemental methods provide

independent checks and periodic corroboration of the surrogate approach used to estimate timeseries values for species not directly measured by the surrogate methods.

1. The reference method s include passive and pressurized whole-air canister samplers used

to collect ambient and breath CO, CO 2 

# , BTEX, MTBE, and 1,3-BD; acidified 2,4-

dinitrophenylhydrazine (DNPH) car tridges to collect HCHO and CH 3 

# CHO; and a multibed (TenaxTA-Carbotrap-Carbosieve) solid adsorbent tube for ambient EtOH (Chicago

only). After collection, these samples are sent to the DRI Organic Analytical Laboratory

for analysis. Canister CO and CO 2 

# are chromatographed and converted to methane for

analysis by flame ionization detectio n (GC/FID); BTEX, MTBE, and 1,3-BD are

quantified by capillary GC/FID [GC/mass spec trometry (MS) for breath samples] using a

separate system (Zielinska et al, 1998). The DNPH cartridges are elut ed with acetonitrile

1-4

# and aldehydes analyzed by high performa nce liquid chromatography (LC) with

photodiode array ultraviolet (UV) detection of their hydrazone derivatives. The multi-bed

sorption tubes are thermally desorbed into a GC and quantified by MS. These methods

are basically standard TO-15, -11A, and - 17 EPA procedures with some improvements

incorporated by DRI as described in Appendix B.

2. The surrogate methods include both active non-dispersiv e infrared (NDIR) and passive

T-15 Langan electrochemical cell devices for CO, and an active photo-ionization detector

(PID) for volatile organic compounds (VOCs) with ionization potentials below 10.6 eV

(principally olefins and ar omatic species). These con tinuous instruments respond to

concentration changes within a few seconds and provide sensitive proportionate measures

of the short-term variability of exhaust and evaporative species quantified by the timeintegrated reference methods. Surrogate me thods are used to generate normalized

continuous time-series of concentrations for BTEX, MTBE, EtOH, 1,3-BD, and the

aldehydes quantified by the reference methods.

3. The supplemental methods include both active continuous BTEX and HCHO instruments

with several minute response times and a passive microextrac tion fiber sampling a

flowing analyte stream for BTEX over a 10-minute period. The continuous BTEX

monitor, a Kore MS200, quan tifies species diffusing through its semi-permeable

membrane inlet by 70eV electron impact ioni zation and time-of-flight MS. The HCHO

instrument bubbles ambient air into a flow ing aqueous 2,4-pentanedione and ammonia

reagent to produce a HCHO-specific product, 3,5-diacetyl-1,4-dihydrolutidene, that is

quantified by UV fluorescence. The 75 um film solid phase microextraction

carboxen/polydimethylsiloxane (SPME-CAR/PD MS) fiber is passively exposed in a

flowing air stream for 10 minutes, retracted into its syringe holder, a nd promptly injected

into a GC with PID/FID detection optimized for BTEX quantification.

All sampling and analysis methods are describe d in detail in Appendi x B. In addition,

the validation of the SPME method is describe d in detail in Appendix C. Quality Assurance

procedures are described in Appendix H.

1.2.3 Exposure Biomarkers

Breath measurements were used as exposure biomarkers in four high-end MEs: out-ofvehicle cabin refueling (ME7); parking in an underground garage (M E11); driving through a

roadway tunnel (ME6); and trailing a high emittin g vehicle (ME13). The test subject took three

breath samples. One sample was taken before initiating ME sampling; the second, ten seconds

immediately after completing the active refueling task or within a minute of experiencing a

measured peak exposure in the other three ME s, and a third, immediately following the second.

The 3 rd 

# sample was analyzed if there was a problem with the second sample. The subject used a

1-liter evacuated canister, placing its inlet t ube into his mouth and breathing smoothly and

regularly through the mouth around the tube unt il a resting tidal breathing pattern was

established. At the end of a normal tidal e xhalation, the subject closed his mouth around the

tube, opened the canister valve expelling his expira tory reserve and filled the canister, collecting

one liter of the expiratory reserve. When the canis ter was filled, the technician closed the canister

valve to capture the sample (Pleil and Lindstr om, 2002; Lindstrom and Pleil, 1996). All breath

samples were analyzed by GC/MS for BTEX, MTBE, 1,3-BD, and EtOH as described by Pleil

1-5

# 1-6 and Lindstrom (2002); CO 2 

# was methanized and quantified by GC /FID. Four subjects, labeled as

1, 2, 3, and 4 in the time- integrated database, were utilized for breath sample measurements.

1.3 Results and Discussion

This section summarizes the di stributions of high-end exposur e levels observed for each

ME by city and season. These exposure levels ar e examined as 20 to 40 minute averages from

the integrated reference measurements, 5-10 minute averages from the surrogate data as

corroborated by the supplemental measures, a nd as peak exposures using the one minute

reconstructed surrogate time series.

1.3.1 Variation of day-to-day exposures by ME in each city

Table 1.3.1-1 and 1.3.1-2 summarize the three city, summer-winter, 20-40 minute

average, maximum, and minimum ME canister leve ls of CO, benzene, an d sum of BTEX and the

HCHO and CH 3 

# CHO values from DNPH cartridges. Av erage, maximum, and minimum in/outcabin temperature and relative humidity (T/ RH) va lues are also listed. In-cabin T/RH values are

in parentheses. Figures 1.3.1-1 through 1.3.1-6 show the day-to-day variations in benzene, 1,3-

BD, HCHO, and CO concentrations.

In general, exposure levels should be propor tionate to the number of sources and their

emission rates in the ME and inverse to increasing distance to the emission source and the extent

of emissions dilution. Dilution is a function of meteorology and the presence of physical

obstructions that may inhibit emissions dispersi on. With the exception of refueling activities, we

generally find that exposure levels are lower in outdoor environments and higher in enclosed

environments. However, substantial variations ex ist among outdoor environm ents with respect to

proximity to emission sources and the magnitude of their emissions. For example, the 40-minute

average exposures for most urban canyon sidewalk /bus stop samples are on the order of a 1-2

ppbv for benzene, whereas benzene exposures on outdoor surface parking lots or toll plaza

aprons are usually higher. Refueling sample s range up to few hundred ppbv benzene over 20

minute sampling times and show substantial day-to-day variability. In-cabin exposures during

vehicle roadway operation show more consiste ncy sample to sample and more temporal

uniformity than the other MEs.

As it could be expected, MTBE and the BTEX species show the highest concentrations in

refueling MEs dominated by evaporative emissi ons whereas CO, HCHO and 1,3-BD are highest

in cold-start dominated MEs ( underground garage, roadway tunnel, toll plaza, surface parking).

Several Houston refueling 1,3-BD values had to be invalidated due to th e interferences stemming

from elevated MTBE concentrations in these ME s. MTBE decomposes slightly (on the order of

1 – 5%) at GC injector temperatures form ing isobutene (2-methylpropene), a decomposition

product that elutes just prior to 1,3-BD on the DB-1 (or equivalent) chromatographic column.

When concentrations of isobutene are much higher than 1,3-BD, they tail into the butadiene peak

biasing its apparent concentra tion upward. This interference wa s confirmed by GC/MS. As noted

in Tables 1.3.1-1 and 1.3.1-2, one value for ME3 and two for ME7 were invalidated in summer

samples and one value for ME3 and four for ME7 in winter samples.Table 1.3.1-1. Summer average, maximum, and minimum ME concentrations (ppbv) of BTEX,1,3-BD, HCHO, CH3CHO, EtOH,MTBE, and CO (ppmv)Atlanta (Conventional Fuel)MEME1ME2ME3ME4ME5ME7ME8ME9ME10ME11ME12ME13Replicates5355353335351,3-butadieneAve.1.70.30.63.60.30.30.20.11.33.60.71.0Min.1.20.10.11.20.00.10.10.00.41.20.50.7Max.2.20.42.17.30.70.60.20.42.26.20.81.1BenzeneAve.6.82.012.320.42.425.91.01.64.628.13.66.0Min.4.21.45.86.01.76.20.91.41.617.73.03.7Max.9.32.422.940.33.774.21.11.89.035.33.99.3TolueneAve.13.64.230.663.24.243.72.54.19.876.55.318.0Min.8.42.415.719.73.110.52.43.63.349.24.99.1Max.21.25.443.0122.66.2104.12.84.719.493.65.637.6ME1: In-cabin congested freeway;ME2: In-cabin urban canyon loop;ME3: In-cabin refueling;ME4: In-cabin underground garage;ME5: In-cabin toll plaza;ME6: In-cabin roadway tunnel;ME7:



# 1-7EthylbenzeneAve.2.20.74.19.90.74.60.40.72.012.80.82.6Min.1.50.41.83.40.51.10.40.60.68.20.81.6Max.3.50.95.118.71.08.70.50.94.017.20.94.8XyleneAve.8.72.915.237.02.617.11.83.08.048.83.610.3Min.5.51.66.612.51.54.41.82.62.930.93.46.1Max.13.73.718.569.23.929.21.93.815.563.43.919.1FormaldehydeAve.6.66.79.325.75.110.010.711.212.833.27.68.6Min.3.95.05.515.44.47.29.610.58.822.27.07.3Max.8.48.511.132.36.211.511.312.519.750.68.311.1AcetaldehydeAve.6.64.64.310.82.83.42.73.04.012.22.45.2Min.2.03.51.27.32.11.12.52.12.57.41.54.4Max.18.66.55.915.13.45.13.14.06.820.93.56.7CO canisterAve.6.11.40.78.52.10.60.81.12.714.53.14.0Min.3.70.70.41.72.00.20.71.00.89.82.82.3Max.11.72.11.416.22.41.21.01.15.620.03.56.2Temp ̊CAve.(22.3)(27.2)(31.7)27.832.3(24.6)(in-cabin)Min.(21.2)(19.6)(30.5)22.131.0(23.6)Max.(23.9)(33.6)(33.8)30.433.8(25.6)RH, %Ave.(57.8)(60.0)(51.8)65.347.4(48.8)(in-cabin)Min.(56.0)(43.0)(46.0)56.041.0(46.0)Max.(59.0)(73.0)(60.0)86.051.0(54.0)Note: Urban canyon loop for Atlanta:Peachtree Street NW, Forsyth-Carnegie, Spring Street NW, and Harris StreetOut-of-cabin refueling;ME8:Out-of-cabin sidewalk;ME9: Out-of-cabin sidewalk/bus stop;ME10: Out-of-cabin surface parking;ME11: Out-of-cabin underground garage;ME12: Outside toll plaza;ME13: In-cabin trailing high-emitter vehicleChicago (Oxygenated Fuel - Ethanol)MEME1ME2ME3ME4ME5ME6ME7ME8ME9ME10ME11ME121,3-butadieneAve.0.40.50.12.40.31.30.10.30.30.61.40.5Min.0.20.30.01.50.21.20.00.30.10.40.20.3Max.0.51.00.14.00.31.60.30.40.40.92.60.8BenzeneAve.2.72.92.18.91.55.84.92.51.73.35.13.1Min.1.71.60.55.61.44.20.61.81.31.81.22.6Max.4.95.24.612.21.58.711.43.62.25.78.23.4TolueneAve.4.84.76.623.32.815.011.23.42.47.511.83.6Min.2.42.61.413.62.36.70.72.01.53.53.42.6Max.9.37.518.637.83.325.527.36.13.513.618.44.3EthylbenzeneAve.0.80.71.73.30.41.91.40.60.50.82.00.6Min.0.40.30.21.80.31.40.10.40.30.70.60.4ME1: In-cabin congested freeway;ME2: In-cabin urban canyon loop;ME3: In-cabin refueling;ME4: In-cabin underground garage;ME5: In-cabin toll plaza;ME6: In-cabin roadway tunnel;ME7:



# 1-8Max.1.31.27.24.50.52.82.60.90.81.13.00.7XyleneAve.3.12.77.213.41.76.65.92.11.83.27.82.3Min.1.61.20.96.91.45.10.51.41.12.72.21.9Max.5.14.529.817.12.09.410.23.43.04.012.12.8FormaldehydeAve.7.75.510.516.15.98.911.76.26.16.710.58.8Min.5.44.68.410.75.38.03.43.83.75.95.86.2Max.9.47.313.726.76.510.124.67.67.88.114.111.6AcetaldehydeAve.6.37.76.310.95.18.44.53.83.73.46.55.4Min.3.64.12.88.14.57.42.53.72.22.53.43.8Max.8.614.79.415.05.88.86.14.04.54.48.37.8CO canisterAve.2.21.70.45.31.45.10.61.01.41.23.13.0Min.1.51.30.34.01.14.00.30.80.91.00.62.5Max.3.02.40.68.21.67.10.71.21.71.85.13.7EtOHAve.6.710.513.015.45.720.628.30.00.81.312.23.1Min.0.04.90.00.00.712.50.00.00.00.00.00.0Max.12.120.036.730.410.429.4115.40.02.43.842.14.9Temp ̊CAve.(23.3)(22.3)(28.3)(26.8)(21.0)(21.7)26.725.026.022.627.331.5(in-cabin)Min.(21.2)(21.9)(25.6)(25.9)(20.3)(20.2)23.523.424.520.722.730.2Max.(25.8)(23.2)(30.2)(28.4)(21.4)(25.0)28.826.527.824.629.733.5RH, %Ave.(51.6)(44.7)(51.5)(60.2)(56.0)(53.0)58.254.352.769.756.042.3(in-cabin)Min.(46.0)(41.0)(45.0)(55.0)(53.0)(50.0)49.053.050.066.045.030.0Max.(55.0)(48.0)(63.0)(65.0)(60.0)(57.0)67.056.055.073.066.056.0Note: Urban canyon loop for Chicago:Lake Street, Wabash Avenue, Van Buren Street, and State StreetOut-of-cabin refueling;ME8:Out-of-cabin sidewalk;ME9: Out-of-cabin sidewalk/bus stop;ME10: Out-of-cabin surface parking;ME11: Out-of-cabin underground garage;ME12: Outside toll plaza;ME13: In-cabin trailing high-emitter vehicleHouston (Oxygenated Fuel – MTBE)MEME1ME2ME3ME4ME5ME6ME7ME8ME9ME10ME11ME121,3-butadieneAve.0.70.40.6*1.70.91.41.2*0.30.10.41.60.9Min.0.30.30.30.20.60.80.50.20.10.30.50.4Max.1.00.50.7*4.51.22.82.1*0.50.20.52.91.4BenzeneAve.1.91.452.65.12.53.7130.71.40.61.65.43.2Min.1.31.25.61.01.92.513.30.70.31.02.31.3Max.2.71.9175.111.13.17.1281.92.60.71.99.85.0TolueneAve.3.42.780.311.54.66.6183.03.31.02.712.05.8Min.2.12.215.92.53.04.127.41.70.71.95.61.7Max.4.23.3277.522.75.513.7425.64.41.33.119.412.2EthylbenzeneAve.0.60.510.62.40.91.321.00.70.20.72.61.3Min.0.40.52.60.60.60.93.50.30.10.51.10.3Max.0.70.735.05.21.12.550.81.30.20.84.52.9ME1: In-cabin congested freeway;ME2: In-cabin urban canyon loop;ME3: In-cabin refueling;ME4: In-cabin underground garage;ME5: In-cabin toll plaza;ME6: In-cabin roadway tunnel;ME7:



# 1-9XyleneAve.2.62.335.79.33.85.471.52.70.92.610.15.6Min.1.72.010.22.52.63.810.21.10.61.84.51.3Max.3.42.8110.218.54.410.3143.05.11.03.216.812.2FormaldehydeAve.5.94.35.26.86.55.87.35.54.15.38.47.3Min.3.42.94.14.94.45.24.54.92.74.56.05.1Max.10.95.17.78.18.96.210.26.46.45.810.110.0AcetaldehydeAve.0.70.60.80.80.80.71.00.70.50.71.00.8Min.0.50.40.70.60.60.60.70.60.40.60.70.6Max.1.20.61.10.91.00.71.30.80.80.71.11.1CO canisterAve.1.71.51.02.91.72.70.60.60.50.83.12.5Min.1.20.90.70.51.71.80.30.50.40.51.11.8Max.2.12.61.67.01.84.50.80.60.71.16.23.2MTBEAve.2.81.31325.511.25.68.831292.91.32.612.28.7Min.2.10.879.84.83.75.1414.31.31.22.16.31.5Max.3.81.74284.118.87.916.557675.41.42.923.720.1Temp ̊CAve.(23.7)(24.5)(28.2)(28.3)(22.5)(24.5)33.131.131.431.728.130.0(in-cabin)Min.(22.9)(23.5)(26.0)(24.0)(21.3)(23.3)28.428.527.928.521.829.5Max.(25.2)(25.7)30.9(33.6)(24.7)(25.6)35.033.433.636.537.130.4RH, %Ave.(54.8)(47.0)(47.6)(47.0)(55.3)(50.2)53.658.358.758.048.867.5(in-cabin)Min.(50.0)(42.0)(41.0)(36.0)(53.0)(47.0)47.041.048.040.041.065.0Max.(62.0)(51.0)(58.0)(57.0)(57.0)(57.0)70.075.077.069.058.070.0Note: Urban canyon for Houston: Louisiana , Clay, Walker, and SmithStreets *For 1,3-BD in Houston, one extreme value for ME3 and two for ME7 were invalidated.Out-of-cabin refueling;ME8:Out-of-cabin sidewalk;ME9: Out-of-cabin sidewalk/bus stop;ME10: Out-of-cabin surface parking;ME11: Out-of-cabin underground garage;ME12: Outside toll plaza;ME13: In-cabin trailing high-emitter vehicleTable 1.3.1-2. Winter average, maximum,and minimum ME concentrations (ppbv)of BTEX, 1,3-BD, HCHO, CH3CHO, EtOH,MTBE, and CO (ppmv)Atlanta (Conventional Fuel)MEME1ME2ME3ME4ME5ME7ME8ME9ME10ME11ME12ME13Replicates5355363335351,3-BDAve.0.60.30.44.10.31.50.20.20.74.00.41.6Min.0.30.00.11.70.20.20.10.10.31.00.30.9Max.0.80.40.77.90.53.60.30.31.56.30.52.8BenzeneAve.2.61.48.426.41.438.50.91.03.521.02.46.7Min.1.90.31.66.11.110.00.70.61.33.21.63.5Max.3.52.317.649.91.799.41.21.36.428.63.211.1TolueneAve.5.34.014.560.53.558.81.51.88.753.03.717.7Min.3.70.84.014.52.223.31.01.22.87.12.29.1Max.7.36.526.4112.74.5125.12.52.715.487.46.033.5ME1: In-cabin congested freeway;ME2: In-cabin urban canyon loop;ME3: In-cabin refueling;ME4: In-cabin underground garage;ME5: In-cabin toll plaza;ME6: In-cabin roadway tunnel;ME7:



# 1-10EthylbenzeneAve.1.00.81.711.50.64.80.30.31.59.70.62.8Min.0.70.10.52.50.52.70.20.20.51.40.41.5Max.1.51.42.622.10.97.40.40.52.715.01.05.4XyleneAve.4.43.26.442.62.617.21.11.35.737.22.411.4Min.3.00.42.29.72.010.20.80.92.05.41.56.0Max.6.25.79.379.73.726.41.61.810.558.53.822.1FormaldehydeAve.6.28.621.919.64.63.42.62.05.011.43.48.4Min.2.65.14.15.63.32.31.41.13.44.03.05.7Max.8.012.489.128.16.05.04.13.16.215.73.710.4AcetaldehydeAve.2.82.95.48.22.02.01.71.52.36.82.54.3Min.0.92.51.54.21.11.11.50.91.32.81.73.6Max.5.63.517.412.03.12.62.11.92.99.83.05.2CO canisterAve.2.61.50.817.71.21.20.80.91.913.22.45.7Min.2.01.30.54.30.90.40.70.60.92.91.52.7Max.3.21.81.436.11.52.21.01.13.921.92.89.0Temp ̊CAve.(21.3)(24.6)(17.9)(21.1)(22.8)10.14.83.810.614.59.4(22.2)(in-cabin)Min.(15.2)(23.1)(15.0)(14.0)(20.6)5.94.11.25.15.56.0(17.9)Max.(28.4)(25.8)(20.2)(24.6)(24.0)16.75.55.714.219.415.3(26.4)RH, %Ave.(35.0)(32.3)(40.4)(41.8)(31.0)54.858.063.052.047.455.7(37.2)(in-cabin)Min.(21.0)(28.0)(28.0)(30.0)(27.0)41.045.045.038.026.022.0(23.0)Max.(48.0)(36.0)(56.0)(47.0)(34.0)81.071.073.063.065.077.0(50.0)Out-of-cabin refueling;ME8:Out-of-cabin sidewalk;ME9: Out-of-cabin sidewalk/bus stop;ME10: Out-of-cabin surface parking;ME11: Out-of-cabin underground garage;ME12: Outside toll plaza;ME13: In-cabin trailing high-emitter vehicleChicago (Oxygenated Fuel - Ethanol)ME1ME2ME3ME4ME5ME6ME7ME8ME9ME10ME11ME121,3-BDAve.0.60.42.84.40.20.50.70.30.30.52.40.3Min.0.20.20.01.60.10.40.20.20.20.11.30.2Max.1.20.613.27.70.20.91.20.50.30.83.20.4BenzeneAve.1.21.35.216.40.72.320.41.01.01.812.91.2Min.0.51.00.25.70.71.41.40.90.90.65.60.9Max.2.21.612.924.20.84.839.11.21.12.920.71.9TolueneAve.1.82.54.629.01.13.113.81.41.22.922.71.3Min.0.52.01.210.81.01.82.11.21.10.912.30.9Max.3.12.98.939.11.36.526.61.81.44.936.42.0EthylbenzeneAve.0.50.40.65.50.20.61.40.30.30.64.40.3Min.0.20.30.01.90.10.40.50.20.20.22.30.2ME1: In-cabin congested freeway;ME2: In-cabin urban canyon loop;ME3: In-cabin refueling;ME4: In-cabin underground garage;ME5: In-cabin toll plaza;ME6: In-cabin roadway tunnel;ME7:



# 1-11Max.0.80.51.47.60.21.43.00.40.31.07.40.4XyleneAve.1.91.52.822.70.82.56.91.10.92.318.31.1Min.0.91.20.27.50.71.41.90.80.90.710.30.8Max.3.61.86.031.20.95.215.71.41.03.829.51.8FormaldehydeAve.7.24.64.313.92.85.33.22.93.54.49.13.0Min.2.13.22.37.21.82.91.82.52.83.32.92.5Max.21.56.07.718.23.57.84.33.24.25.915.33.6AcetaldehydeAve.5.03.13.612.72.33.82.82.12.52.57.62.2Min.1.12.42.45.91.41.52.01.62.11.41.62.0Max.16.84.57.417.72.96.93.82.73.13.812.82.6CO canisterAve.1.51.00.412.00.92.20.70.90.91.711.01.7Min.1.10.40.44.50.81.70.20.70.80.63.81.3Max.2.11.40.518.41.03.41.81.11.02.716.82.0EtOHAve.6.82.15.11.44.31.62.21.84.03.33.70.9Min.1.60.02.80.11.40.00.00.00.01.31.90.0Max.12.33.19.82.67.92.74.83.98.05.96.02.3Temp ̊CAve.(21.5)(22.8)(17.3)(21.6)(22.6)(20.9)1.64.96.56.4(17.0)1.9(in-cabin)Min.(18.1)(21.3)(11.2)(15.9)(21.6)(16.3)-3.31.32.14.1(13.6)0.0Max.(30.6)(24.8)(19.8)(24.7)(23.5)(24.7)6.69.512.38.7(22.1)4.6RH, %Ave.(19.2)(23.7)(22.0)(37.5)(17.7)(24.8)44.746.342.737.0(41.4)53.0(in-cabin)Min.(9.0)(21.0)(13.0)(25.0)(13.0)(14.0)32.032.027.032.0(29.0)25.0Max.(25.0)(25.0)(32.0)(60.0)(21.0)(41.0)62.062.060.042.0(61.0)77.0Out-of-cabin refueling;ME8:Out-of-cabin sidewalk;ME9: Out-of-cabin sidewalk/bus stop;ME10: Out-of-cabin surface parking;ME11: Out-of-cabin underground garage;ME12: Outside toll plaza;ME13: In-cabin trailing high-emitter vehicleHouston (Oxygenated Fuel - MTBE)ME1ME2ME3ME4ME5ME6ME7ME8ME9ME10ME11ME121,3-BDAve.0.41.21.8*3.80.51.11.9*0.10.21.72.70.8Min.0.30.40.40.40.40.11.9*0.10.10.20.40.5Max.0.62.73.65.70.62.31.9*0.20.24.34.31.3BenzeneAve.1.43.717.710.61.72.755.00.50.65.07.82.5Min.1.11.42.31.61.40.77.70.50.41.51.41.8Max.2.08.256.614.52.14.297.70.70.811.913.73.8TolueneAve.3.06.525.621.83.64.664.30.81.110.517.34.2Min.2.32.94.24.23.21.610.90.70.83.53.12.7Max.5.213.469.730.93.86.7106.01.01.421.731.46.3EthylbenzeneAve.0.71.42.44.30.80.94.50.20.31.93.30.8Min.0.50.70.71.10.70.41.80.20.20.70.70.5ME1: In-cabin congested freeway;ME2: In-cabin urban canyon loop;ME3: In-cabin refueling;ME4: In-cabin underground garage;ME5: In-cabin toll plaza;ME6: In-cabin roadway tunnel;ME7:



# 1-12Max.1.12.64.45.90.81.48.00.20.34.35.81.2XyleneAve.3.46.310.917.63.54.418.70.81.18.113.93.6Min.2.53.33.65.53.51.54.40.70.73.43.72.1Max.5.911.518.424.73.66.935.21.01.417.525.06.3FormaldehydeAve.4.58.27.110.53.87.65.72.12.54.05.75.0Min.3.04.74.67.92.75.43.51.92.01.22.94.0Max.5.112.68.412.14.58.810.62.33.17.68.66.1AcetaldehydeAve.1.94.36.55.31.94.45.31.71.74.53.42.0Min.1.22.53.54.71.52.63.21.41.23.41.01.8Max.2.47.09.25.92.26.110.01.91.95.74.92.4CO canisterAve.1.43.71.27.81.82.91.00.40.53.46.02.7Min.0.91.40.51.11.60.80.30.30.40.71.11.7Max.1.66.92.712.52.15.52.60.50.78.49.84.5MTBEAve.3.910.2890.625.44.27.32568.90.50.715.126.06.7Min.1.42.623.31.83.23.3347.80.50.66.52.72.6Max.8.125.33135.368.14.810.45629.90.60.820.963.613.2Temp ̊CAve.(22.3)(22.9)(21.6)(22.6)(21.0)(22.4)15.79.811.417.115.514.9(in-cabin)Min.(18.0)(20.4)(19.3)(19.9)(19.1)(19.9)10.97.27.913.410.37.9Max.(26.5)(24.3)(23.4)(25.2)(22.2)(24.8)20.912.214.721.018.620.2RH, %Ave.(41.2)(36.7)(52.0)(54.2)(49.3)(46.0)67.061.055.363.069.677.7(in-cabin)Min.(29.0)(33.0)(37.0)(36.0)(43.0)(34.0)55.053.046.048.043.070.0Max.(58.0)(42.0)(61.0)(69.0)(56.0)(54.0)77.071.067.076.087.083.0*Note: For 1,3-BD in Houston, one extreme value for ME3 and four for ME7 were invalidatedOut-of-cabin refueling;ME8:Out-of-cabin sidewalk;ME9: Out-of-cabin sidewalk/bus stop;ME10: Out-of-cabin surface parking;ME11: Out-of-cabin underground garage;ME12: Outside toll plaza;ME13: In-cabin trailing high-emitter vehicleME1: In-cabin congested freeway;ME2: In-cabin urban canyon;ME3: In-cabin refueling;ME4: In-cabin underground garage;ME5: In-cabin toll plaza;ME6: In-cabin roadway tunnel;ME7: Out-of

# 1-13Microenvironments

ppbvAtlanta, Summer 2002-20031,3 - ButadieneME1ME2ME3ME4ME5ME7ME8ME9ME10ME11ME12ME1300.81.62.43.244.85.66.47.28MaximumMinimum75%25%MedianOutliersExtremesMicroenvironment

ppbvAtlanta, Summer 2002-2003BenzeneME1ME2ME3ME4ME5ME7ME8ME9ME10ME11ME12ME1308162432404856647280MaximumMinimum75%25%MedianOutliersExtremesMicroenvironment

ppmCOME1ME2ME3ME4ME5ME7ME8ME9ME10ME11ME12ME1302468101214161820MaximumMinimum75%25%MedianOutliersExtremesMicroenvironment

ppbvFormaldehydeME1ME2ME3ME4ME5ME7ME8ME9ME10ME11ME12ME130510152025303540455055MaximumMinimum75%25%MedianOutliersExtremesFigure 1.3.1-1. Time-integrated exposure levels indifferent MEs in Atlanta, Summer 2002 and 2003cabin refueling;ME8:Out-of-cabin sidewalk;ME9: Out-of-cabin sidewalk/bus stop;ME10: Out-of-cabin surface parking;ME11: Out-of-cabin underground garage;ME12: Outside toll plaza;ME13:In-cabin trailing high-emitter vehicleMicroenvironment

ppbvAtlanta, Winter 2004BenzeneME1ME2ME3ME4ME5ME7ME8ME9ME10ME11ME12ME130102030405060708090100MaximumMinimum75%25%MedianOutliersExtremesMicroenvironment

ppbvAtlanta, Winter 20041,3-ButadianeME1ME2ME3ME4ME5ME7ME8ME9ME10ME11ME12ME1300.81.62.43.244.85.66.47.28MaximumMinimum75%25%MedianOutliersExtremesME1: In-cabin congested freeway;ME2: In-cabin urban canyon;ME3: In-cabin refueling;ME4: In-cabin underground garage;ME5: In-cabin toll plaza;ME6: In-cabin roadway tunnel;ME7: Out-of

# 1-14Microenvironment

ppmCOME1ME2ME3ME4ME5ME7ME8ME9ME10ME11ME12ME130481216202428323640MaximumMinimum75%25%MedianOutliersExtremesMicroenvironment

ppbFormaldehydeME1ME2ME3ME4ME5ME7ME8ME9ME10ME11ME12ME13036912151821242730MaximumMinimum75%25%MedianOutliersExtremesFigure 1.3.1-2. Time-integrated exposure levelsin different MEs in Atlanta, Winter 2004cabin refueling;ME8:Out-of-cabin sidewalk;ME9: Out-of-cabin sidewalk/bus stop;ME10: Out-of-cabin surface parking;ME11: Out-of-cabin underground garage;ME12: Outside toll plaza;ME13:In-cabin trailing high-emitter vehicleME1: In-cabin congested freeway;ME2: In-cabin urban canyon;ME3: In-cabin refueling;ME4: In-cabin underground garage;ME5: In-cabin toll plaza;ME6: In-cabin roadway tunnel;ME7: Out-of

# 1-15Microenvironments

ppbvChicago, Summer 2003BenzeneMicroenvironments

ppbvChicago, Summer 20031, 3-ME1ME2ME3ME4ME5ME6ME7ME8ME9ME10ME11ME1200.511.522.533.544.5MaximumMinimum75%25%MedianOutliersExtremesME1ME2ME3ME4ME5ME6ME7ME8ME9ME10ME11ME1201.534.567.5910.51213.5MaximumMinimum75%25%MedianOutliersExtremesMicroenvironments

ppbvFormaldehydeME1ME2ME3ME4ME5ME6ME7ME8ME9ME10ME11ME120369121518212427MaximumMinimum75%25%MedianOutliersExtremesMicroenvironments

ppmCOME1ME2ME3ME4ME5ME6ME7ME8ME9ME10ME11ME1200.81.62.43.244.85.66.47.288.8MaximumMinimum75%25%MedianOutliersExtremesFigure 1.3.1-3. Time-integrated exposure levelsin different MEs inChicago, Summer 2003cabin refueling;ME8:Out-of-cabin sidewalk;ME9: Out-of-cabin sidewalk/bus stop;ME10: Out-of-cabin surface parking;ME11: Out-of-cabin underground garage;ME12: Outside toll plaza;ME13:In-cabin trailing high-emitter vehicleME1: In-cabin congested freeway;ME2: In-cabin urban canyon;ME3: In-cabin refueling;ME4: In-cabin underground garage;ME5: In-cabin toll plaza;ME6: In-cabin roadway tunnel;ME7: Out-of

# 1-16MicroenvironmentMicroenvironment

ppbvChicago, Winter 2004.xlsBenzeneMicroenvironments

ppbvChicago, Winter 20041,3-ButadieneME1ME2ME3ME4ME5ME6ME7ME8ME9ME10ME11ME1200.81.62.43.244.85.66.47.28MaximumMinimum75%25%MedianOutliersExtremesME1ME2ME3ME4ME5ME6ME7ME8ME9ME10ME11ME120481216202428323640MaximumMinimum75%25%MedianOutliersExtremesMicroenvironment

ppmCOME1ME2ME3ME4ME5ME6ME7ME8ME9ME10ME11ME1202468101214161820MaximumMinimum75%25%MedianOutliersExtremes ppbvFormaldehydeME1ME2ME3ME4ME5ME6ME7ME8ME9ME10ME11ME1202468101214161820MaximumMinimum75%25%MedianOutliersExtremesFigure 1.3.1-4. Time-integrated exposure levelsin different MEs inChicago, Winter 2004cabin refueling;ME8:Out-of-cabin sidewalk;ME9: Out-of-cabin sidewalk/bus stop;ME10: Out-of-cabin surface parking;ME11: Out-of-cabin underground garage;ME12: Outside toll plaza;ME13:In-cabin trailing high-emitter vehicleME1: In-cabin congested freeway;ME2: In-cabin urban canyon;ME3: In-cabin refueling;ME4: In-cabin underground garage;ME5: In-cabin toll plaza;ME6: In-cabin roadway tunnel;ME7: Out-of

# 1-17Microenvironments

ppbvHouston, Summer 20041,3-ButadianeME1ME2ME3ME4ME5ME6ME7ME8ME9ME10ME11ME1200.511.522.533.544.5MaximumMinimum75%25%MedianOutliersExtremesMicroenvironment

ppbvHouston, Summer 2004BenzeneME1ME2ME3ME4ME5ME6ME7ME8ME9ME10ME11ME120306090120150180210240270300MaximumMinimum75%25%MedianOutliersExtremesMicroenvironment

ppmCOME1ME2ME3ME4ME5ME6ME7ME8ME9ME10ME11ME120123456789MaximumMinimum75%25%MedianOutliersExtremesMicroenvironment

ppbvFormaldehydeME1ME2ME3ME4ME5ME6ME7ME8ME9ME10ME11ME1201.534.567.5910.512MaximumMinimum75%25%MedianOutliersExtremesFigure 1.3.1-5. Time-integrated exposure levelsin different MEs inHouston, Summer 2004cabin refueling;ME8:Out-of-cabin sidewalk;ME9: Out-of-cabin sidewalk/bus stop;ME10: Out-of-cabin surface parking;ME11: Out-of-cabin underground garage;ME12: Outside toll plaza;ME13:In-cabin trailing high-emitter vehicle: In-cabin congested freeway;ME2: In-cabin urban canyon;ME3: In-cabin refueling;ME4: In-cabin underground garage;ME5: In-cabin toll plaza;ME6: In-cabin roadway tunnel;ME7: Out-ofcabin refueling;ME8:Out-of-cabin sidewalk;ME9: Out-of-cabin sidewalk/bus stop;ME10: Out-of-cabin surface parking;ME11: Out-of-cabin underground garage;ME12: Outside toll plaza;ME13:gh-emitter vehicleMicroenvironments

ppbvHouston, Winter 20051,3-ButadianeME1ME2ME3ME4ME5ME6ME7ME8ME9ME10ME11ME1200.61.21.82.433.64.24.85.46MaximumMinimum75%25%MedianOutliersExtremesMicroenvironment

ppmCOME1ME2ME3ME4ME5ME6ME7ME8ME9ME10ME11ME1201.534.567.5910.51213.5MaximumMinimum75%25%MedianOutliersExtremesMicroenvironment

ppbvFormaldehydeME1ME2ME3ME4ME5ME6ME7ME8ME9ME10ME11ME1201.534.567.5910.51213.5MaximumMinimum75%25%MedianOutliersExtremesFigure 1.3.1-6. Time-integrated exposure levelsin different MEs inHouston, Winter 2005MicroenvironmentHouston, Winter 2005BenzeneME1In-cabin trailing hi



# 1-18 ppbvME1ME2ME3ME4ME5ME6ME7ME8ME9ME10ME11ME120102030405060708090100MaximumMinimum75%25%MedianOutliersExtremes

# 1.3.2 Distribution of exposures within MEs in each city (1-minute time series)

The study protocol (Appendix A) specifies a sampling period of 20 (ME3/ME7) to 40

minutes beginning at the top of the hour to co rrelate with the local air quality monitoring

network sampling periods. Because large variati ons are expected within these time frames in

exposures for most MEs, the protocol includes continuous measurements of target species with

time resolutions of about a minute. The suppl emental Kore MS200 MS (deployed for BTEX)

and Alpha Omega HCHO analyzer used to measure these species at 1-minut e resolutions directly

had not been earlier proven under such field conditions and only worked well intermittently.

Furthermore, there were no acceptable c ontinuous methods for 1,3-BD, MTBE, EtOH,

CH 3 

# CHO, or non-methane VOCs (NMVOC) that could be used in portable modes of operation

with the necessary sensitivity. Accordingly, our sampling strategy consisted of a three-tiered

approach classified as referen ce, surrogate, and confirmatory measurements. The base set or

reference (R) measurements consis t of three well-estab lished time-integrated methods (canisters,

DNPH, and solid adsorbent cartridges) as described in Section 1.2.2. These three methods

together measure all species of interest over the 20-40 minute sampling periods within each ME

and had excellent data capture rates. Although the integrated me thods do not characterize shortterm peak exposures in MEs with highly vary ing exposure levels, they provide a basis for

quantifying and deriving correlati ons between the integrated valu es and continuous surrogate (S)

measures, such as the CO and PID NMVOC monito rs, in order to reconstruct short-term time

series. For example, data for BTEX, and 1, 3-BD from the canister measurements can be used to

normalize continuous CO and NMVOC traces taken over the same periods to construct

component time series in exhaust-dominated envi ronments. In a similar manner, the time series

of HCHO values can be reconstructed from the correlation of the integrated DNPH samples with

continuous CO measures.

Tables 1.3.2-1A and 1.3.2-1B list correlation coefficients (R 2 

# ), slopes, P-values and

performance statistic for correlations of be nzene, 1,3-BD, HCHO, and CO measured from

canisters with NMVOC PID and continuous CO, measured by NDIR, for all ME with exception

of ME3 and ME7, and for ME3 and ME7 only, resp ectively. It can be seen from Table 1.3.2-1A

that 1,3-BD correlates with CO somewhat better than with NMVOC so continuous CO values

were used for reconstructing 1-minute time seri es for 1,3-BD for all MEs with exception of

refueling experiments (ME3 and ME7). Howe ver, for refueling MEs (Table1.3.2-1B), the

correlations are worse, although the correlations of benzene with NMVOC ar e still statistically

significant for all three cities. The correlations of 1,3-BD with NMVOC PID and CO_NDIR are

not statistically si gnificant, since neither 1,3-BD, nor CO is abundant in evaporative emissions.

Thus, the calculation of 1-min time series for 1,3-BD in ME3 and ME7 is not valid for

evaporative gasoline exposure. However, these speci es are often measured at some gas stations,

since they originate from exhaust emissions of higher-emitting vehicles. In addition, HCHO does

not correlate very well with CO probably due to the photochemical production of this compound

in outdoor MEs.

The reconstructed 1-minute peak exposures we re calculated based on the method used in

the Atlanta Summer 2002 and Atlanta and Chicago Summer 2003 (Zielinska et al, 2003b, 2004b)

reports. The NMVOC PID time series was used to reconstruct benzene values (the remaining

TEX species follow the benzene time series) and the CO time series was used to reconstruct

HCHO and 1,3-BD values. No CO and NMVOC da ta were used where the average CO or

1-19

# 1-20 NMVOC was below the approximate detection limit of the instruments (0.5 ppmv and 25 ppbv,

respectively). In each case the approach was the same. The mean value of the compound to be

reconstructed was multiplied by the ratio of the surrogate mean to the instantaneous reading. For

example, to produce the 1 st 

# minute value for benzene, the mean benzene canister value was

multiplied by the 1 st 

# minute NMVOC reading divided by the mean NMVOC reading. For HCHO

and 1,3-BD, the NDIR CO value was used for a ll cases where it was av ailable and valid.

A summary of the reconstructed data is presented in Tables 1.3.2-2 and 1.3.2-3 for

benzene, 1,3-BD and HCHO (the complete data se t is submitted in electronic form) for summer

and winter, respectively. The av erage maximum and minimum valu es for each ME in each city

and season are shown. The reconstructed time seri es are graphically presented in Figure 1.3.2-1

through 1.3.2-3 for selected MEs to illust rate the variability of exposure.

For in-cabin exposures in Figure 1.3.2-1 a nd upper part of Figure 1.3.2-2, the first 20

minutes of measurement was carried out under hi gh ventilation conditions (i.e. window open, air

recirculation off), whereas for the remaining 20 minutes at low ventilation (i.e. window closed,

air conditioning or heating on, ai r recirculation on). As can be seen, the second 20 minutes of

measurement are less variable. In addition, the concentrati on of benzene is rising steadily for this

latter sampling period, reflecti ng the rising NMVOC signal, pr obably due to accumulation of

outgasing emissions from vehicle ca bin material and the breath of people present in the vehicle

cabin.

For refueling experiments (in-cabin ME3 a nd active out-of-cabin refueling ME7) the

highest exposures occurred during the active refueli ng performed during the second 10 minutes

of the sampling period. The highest concentrations are observed for BTEX species as expected

from evaporative and spillage emissions duri ng active refueling. HCHO and 1,3-BD present in

exhaust emissions are lower and usually not correla ted with benzene, as can be seen for ME3 in

Fig. 1.3.2-2.

As shown in Figure 1.3.2-3, outdoor exposures (ME8, ME9 and ME12) are usually low

and less variable. HCHO seems higher than benzen e and 1,3-BD as is also evident from Figures

1.3.1-1 to 1.3.1-6 and Tables 1.3.1-1 and -2. On th e other hand, outdoor surface parking (ME10)

and out-of-cabin underground garage (ME11) ME s show much higher variability corresponding

to vehicles exiting the parking lots after the game (ME10) or at the end of a work day (ME11).

We collected 5-minute canister samples at peak of exposures for ME7, ME11, and ME6

in Houston and Chicago and ME13 in Atlanta. Ta ble 1.3.2-4 shows the average concentrations of

BTEX, 1,3-BD and MTBE for these selected samples (full data set provided in electronic form).

Figures 1.3.2-4 show the correlations for be nzene and 1,3-BD, respectively, quantified from

these 5-minute canisters and averaged ove r corresponding 5-minute surrogate 1-minute

measurements. ME7 values for Houston were re moved from these correla tions since high MTBE

levels distort NMVOC PID signal correlation to benzene. An obvious outlie r from Atlanta (ME7,

summer) was also removed. As seen from these fi gures, correlations are reasonable, especially

for benzene (R 2 

# = 0.87).Table 1.3.2-1A. Correlation coefficients (R2) and associated statistic for relationships of time-integrated measurements withcontinuous methods (NMVOC and CO)for 3 cities, without ME3 and ME7PIDCO_NDIRr2SlopeInterceptdfFstatFcritP-valuer2SlopeInterceptdfF-statFcritP-valueAtlantaBenzene0.887.362.38886753.90.00%1,3-BD0.5531.0520.29881073.90.00%0.682.431.2541884.10.00%Formaldehyde0.390.351.7941274.10.00%CO_can0.930.90-0.01415144.10.00%ChicagoBenzene0.827.86-0.85874064.00.00%1,3-BD0.6125.556.33871364.00.00%0.702.350.82461064.0520.00%Formaldehyde0.200.380.6546114.0520.15%CO_can0.940.95-0.07466874.0520.00%



# 1-21HoustonBenzene0.709.0226.16711624.00.00%1,3-BD0.7024.8628.75711694.00.00%0.812.000.11431814.10.00%Formaldehyde0.290.70-1.3743184.10.01%CO_can0.881.08-0.38433094.10.00%Notes:F-stat = performance statistic for regression slope of 2-tailedpaired data: Critical F-value for 95% confidence is shown.P-value = probability that correlation is not significantdf = degrees of freedom (number of data pairs - 2)Table 1.3.2-1B. Correlation coefficients (R2) and associated statistic for relationships of time-integrated measurements withcontinuous methods (NMVOC and CO) for ME3 and ME7 in 3 citiesPIDCO_NDIRr2SlopeInterceptdfFstatFcritP-valuer2SlopeInterceptdfF-statFcritP-valueAtlantaBenzene0.5712.151274.8453704.00.00%1,3-BD0.34159.97729.814754.02.47%0.06-0.030.551214.741.71%Formaldehyde0.010.021.092118.538.31%CO_can0.410.580.592218.528.05%ChicagoBenzene0.9615.76-4.47255904.20.00%1,3-BD0.0443.11238.602514.230.37%insufficient data availableFormaldehydeinsufficient data availableCO_caninsufficient data availableHoustonBenzene0.5210.942896.6527304.20.00%1,3-BD0.22116.191878.181954.43.36%0.010.010.92516.634.28%Formaldehyde0.42-0.222.723210.122.15%CO_can0.750.78-0.0831110.14.49%



# 1-22Notes:F-stat = performance statistic for regression slope of 2-tailedpaired data: Critical F-value for 95% confidence is shown.P-value = probability that correlation is not significantdf = degrees of freedom (number of data pairs - 2)

# Table 1.3.2-2. Summary of the reconstr ucted 1-minute data (ppbv), Summer

City ME Benzene 1,3-BD HCHO

min max min max min max

A 01 0.00 47.38 0.00 16.59 0.00 34.25

A 02

A 03 0.00 103.60 0.00 0.67 0.00 29.42

A 04 0.00 49.48 0.00 8.20 0.00 92.53

A 05

A 07 0.00 976.35

A 08

A 09

A 10 0.95 18.57 0.00 8.55 0.00 75.30

A 11 7.68 51.30 0.90 9.19 12.82 70.80

A 12 1.62 11.57 0.31 3.40 3.79 29.95

A 13 0.00 253.74 0.00 19.14 0.00 141.72

C 01 0.00 31.98 0.01 0.85 0.00 13.56

C 02 0.00 11.42 0.01 1.75 0.11 13.09

C 03 0.00 30.18

C 04 0.50 15.39 0.74 4.61 3.64 35.66

C 05 0.80 0.00 17.55

C 06 0.10 65.31 0.20 11.65 1.13 64.03

C 07 0.00 111.01

C 08 0.29 0.40 3.81 7.65

C 09 0.15 0.45 3.66 7.85

C 10 0.01 2.14 0.04 14.25

C 11 0.20 20.73 0.09 4.11 0.00 25.99

C 12 0.31 0.77 6.15 11.60

H 01 0.95 6.89 0.06 9.25 0.50 47.92

H 02 0.82 2.02 0.03 7.95 0.27 78.24

H 03 0.00 1346.97 0.23 3.66 1.67 26.55

H 04 2.09 13.44 0.48 6.00 1.86 23.44

H 05 1.19 4.04 0.14 2.80 0.63 26.49

H 06 1.31 16.95 0.12 6.23 0.89 25.61

H 07 0.00 1948.10 2.85 45.79

H 08 0.27 2.80 0.00 0.68 0.00 17.17

H 09 0.18 0.87 0.04 0.43 1.20 17.69

H 10 0.90 5.71 0.11 3.93 1.47 50.49

H 11 1.88 15.71 0.14 6.08 1.13 53.69

H 12 0.85 17.54 0.08 2.74 0.95 13.09

1-23

# Table 1.3.2-3. Summary of the reconstr ucted 1-min data (ppbv), Winter

City ME Benzene 13-BD Formaldehyde

min max min max min max

A 01 0.02 1.28 0.25 15.70

A 02 1.60 3.87 0.07 1.34 0.82 15.71

A 03 0.59 107.31

A 04 2.71 67.30 0.07 13.32 0.22 43.93

A 05 0.02 1.98 0.24 17.49

A 07 0.00 1080.63 3.44 19.02

A 08 0.74 2.17 0.23 0.41 3.15 5.69

A 09 1.06 1.81 0.27 0.53 2.48 4.79

A 10 3.11 13.55 0.08 3.07 1.35 41.48

A 11 1.66 49.76 0.05 17.32 0.21 50.86

A 12 0.81 6.53 0.17 1.33 1.11 11.75

A 13 0.53 33.96 0.05 6.36 0.20 42.78

C 01 0.17 1.20 0.07 7.40 0.26 64.35

C 02

C 03 0.00 98.94

C 04 3.72 31.25 0.97 8.97 4.45 25.70

C 05 0.04 0.72 0.65 11.37

C 06 0.13 8.53 0.06 1.63 0.45 14.92

C 07 0.00 511.90 0.58 4.57 0.86 6.75

C 08 0.10 1.71 0.94 10.07

C 09 0.00 0.53 0.00 8.02

C 10 0.07 2.54 0.47 18.27

C 11 3.01 33.48 0.11 5.63 0.45 26.76

C 12 0.00 0.65 0.00 8.87

H 01 0.60 6.34 0.06 3.13 0.58 23.47

H 02 0.82 13.93

H 03 0.47 335.71 0.11 1.86 0.74 12.11

H 04 1.22 17.85 0.11 6.57 2.40 33.89

H 05 0.67 3.25 0.07 1.68 0.69 16.77

H 06 0.46 7.77 0.01 4.72 0.15 23.07

H 07 0.15 1203.84 0.25 20.29

H 08 0.35 0.62

H 09 0.28 1.06

H 10 1.16 32.64 0.08 12.89 0.13 22.73

H 11 3.71 18.66 1.23 12.10 2.41 16.98

H 12 1.43 3.76

1-24

# Table 1.3.2-4. Summary of the 5- minute canister data (ppbv)

City Atlanta, Summer Atlanta, Winter

ME 7 11 13 7 11 13

Replicates 5 5 4 6 5 5

1,3-BD Ave. 1.53 5.39 1.20 6.48 7.23 1.79

Min. 0.04 3.97 0.79 0.78 0.51 0.48

Max. 4.09 7.50 1.90 15.47 10.13 2.72

Benzene Ave. 163.98 33.26 6.30 89.52 27.95 8.11

Min. 3.06 24.80 4.36 13.52 1.51 1.90

Max. 475.82 45.07 10.34 256.31 42.40 16.02

Toluene Ave. 253.17 94.52 15.30 139.88 70.84 29.44

Min. 8.90 68.88 10.97 48.39 3.94 4.62

Max. 649.81 126.79 20.41 360.24 113.45 67.34

Ethylbenzene Ave. 23.15 16.06 2.42 8.82 11.89 3.91

Min. 1.45 11.89 1.89 3.86 0.64 0.69

Max. 57.14 22.88 2.93 20.24 19.79 8.50

Xylene Ave. 79.33 62.04 9.60 29.86 48.27 17.52

Min. 6.21 44.84 7.39 15.90 2.69 3.01

Max. 202.27 87.73 12.72 64.24 77.88 38.85

City Chicago, Summer Chicago, Winter

ME 6 7 11 6 7 11

Replicates 5 5 5 5 4 4

1,3-BD Ave. 1.51 0.21 2.33 0.73 2.19 4.00

Min. 0.94 0.03 0.80 0.51 1.44 1.79

Max. 2.66 0.39 3.01 1.45 2.74 5.75

Benzene Ave. 8.87 13.56 7.75 2.22 84.25 12.00

Min. 4.11 0.56 2.50 1.59 24.98 6.15

Max. 24.00 37.23 10.00 3.94 160.53 17.32

Toluene Ave. 25.53 22.74 19.40 3.56 56.51 23.92

Min. 5.87 0.57 5.57 2.14 32.96 12.82

Max. 78.10 61.34 25.73 6.48 100.48 36.75

Ethylbenzene Ave. 2.69 2.77 3.31 0.59 6.11 4.03

Min. 1.23 0.11 1.17 0.36 2.12 2.01

Max. 6.80 6.78 4.63 1.04 11.90 6.00

Xylene Ave. 9.43 11.19 12.74 2.89 25.92 18.75

Min. 4.83 0.38 4.35 1.67 9.31 9.43

Max. 23.42 26.91 18.57 5.33 51.91 27.41



# 1-25

# 1-26 City Houston, Summer Houston, Winter

ME 6 7 11 6 7 11

Replicates 4 5 5 5 5 5

1,3-BD Ave. 4.55 4.04 4.22 1.79 76.1 1 3.18

Min. 1.24 1.36 0.55 0.81 13.0 3 0.39

Max. 10.07 6.72 12.8 5 3.18 174. 21 5.15

Benzene Ave. 12.51 918.86 11.0 5 4.32 379.48 9.47

Min. 4.17 181.85 1.99 2.53 49.61 1.91

Max. 27.86 2429.61 26.71 7.91 607.22 16.60

Toluene Ave. 21.28 815.73 27.3 1 7.30 420.64 19.8 4

Min. 6.59 360.54 4.79 4.98 64.85 2.98

Max. 50.32 1142.43 62.52 13.5 2 835. 98 38.04

Ethylbenzene Ave. 4.25 94.58 5.34 1.32 23.92 3.85

Min. 1.47 44.53 1.12 0.85 4.22 0.50

Max. 10.08 135.65 13.00 2.70 51.83 7.59

Xylene Ave. 5.31 368.47 6.40 5.78 100.90 16.07

Min. 6.74 132.36 4.38 4.13 16.87 2.14

Max. 11.78 553.69 15.03 10.9 8 205. 55 32.78

MTBE Ave. 36.50 26977.95 30.06 15.2 8 9705 .27 32.96

Min. 13.65 3319.53 5.71 5.47 2019.60 14.29

Max. 67.35 61643.39 48.23 39.3 4 1548 4.50 65.53ME1, Houston Summer 200402468101214 0708 0710 0712 0714 0716 0718 0720 0722 0724 0726 0728 0730 0732 0734 0736 0738 0740 0742 0744 0746 0748

ppbvbenz_pidbud13_coform_coME2, Atlanta Winter 20040.00.51.01.52.02.53.03.54.04.5 0745 0746 0747 0748 0749 0750 0751 0752 0753 0754 0755 0756 0757 0758 0759 0800 0801 0802 0803 0804 0805 0806 0807 0808 0809 0810 0811 0812 0813 0814 0815 0816 0817 0818 0819 0820 0821 0822 0823 0824 0825

Benzene, 1,3-BD, ppbv024681012141618 Formaldehyde, ppbvbenz_pid13-BD_coForm_coME1: In-cabin congested freeway;ME2: In-cabin urban canyon;ME3: In-cabin refueling;ME4: In-cabin underground garage;ME5: In-cabin toll plaza;ME6: In-cabin roadway tunnel;ME7: Out-of

# 1-27ME4, Atlanta Summer 20030510152025301720 1723 1726 1729 1732 1735 1738 1741 1744 1747 1750 1753 1756 1759

ppbvbenz_pid13-BD_coForm_coME5, Houston Summer 20040246810 0705 0707 0709 0711 0713 0715 0717 0719 0721 0723 0725 0727 0729 0731 0733 0735 0737 0739 0741 0743 0745

ppbvbenz_pidbud13_coform_coFigure 1.3.2-1. 1-Minute time series forin-cabin exposures: ME1 (congested freeway), ME2 (urban canyon); ME4 (undergroundgarage) and ME5 (toll plaza)cabin refueling;ME8:Out-of-cabin sidewalk;ME9: Out-of-cabin sidewalk/bus stop;ME10: Out-of-cabin surface parking;ME11: Out-of-cabin underground garage;ME12: Outside toll plaza;ME13:In-cabin trailing high-emitter vehicleME1: In-cabin congested freeway;ME2: In-cabin urban canyon;ME3: In-cabin refueling;ME4: In-cabin underground garage;ME5: In-cabin toll plaza;ME6: In-cabin roadway tunnel;ME7: Out-of

# 1-28ME6, Houston Summer 2004024681012141618 0747 0749 0751 0753 0755 0757 0759 0801 0803 0805 0807 0809 0811 0813 0815 0817 0819 0821 0823 0825 0827

ppbvbenz_pidbud13_coform_coME13, Atlanta Winter 200405101520253035

1131 1133 1135 1137 1139 1141 1143 1145 1147 1149 1151 1153 1155 1157 1159 1201 1203 1205 1207 1209 1211

ppbvbenz_pid13-BD_coForm_coME3, Chicago, Winter 20040204060801001201330 1332 1334 1336 1338 1340 1342 1344 1346 1348 1350

ppbbenz_pid13BD_coForm_coME7, Houston Summer 200405001000150020002500 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1300 1301 1302 1303 1304 1305 1306 1307 1308

ppbvbud13_coform_cobenz_pidFigure 1.3.2-2.1-Minute time series for in-cabin exposures: ME6 (tunnel); ME13 (following high-emitting vehicle); ME3 (in-cabinrefueling) and out-of-cabin refueling, ME7cabin refueling;ME8:Out-of-cabin sidewalk;ME9: Out-of-cabin sidewalk/bus stop;ME10: Out-of-cabin surface parking;ME11: Out-of-cabin underground garage;ME12: Outside toll plaza;ME13:In-cabin trailing high-emitter vehicleME1: In-cabin congested freeway;ME2: In-cabin urban canyon;ME3: In-cabin refueling;ME4: In-cabin underground garage;ME5: In-cabin toll plaza;ME6: In-cabin roadway tunnel;ME7: Out-of

# 1-29ME8, Atlanta Winter 20040123456 1155 1157 1159 1201 1203 1205 1207 1209 1211 1213 1215 1217 1219 1221 1223 1225 1227 1229 1231 1233

ppbvbenz_pid13-BD_coForm_coME10, Chicago, Summer 20030510152025 2100 2101 2102 2103 2104 2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 2115 2116 2117 2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137 2138 2139 2140 2141 2142 2143 2144 2145 2146 2147 2148 2149 2150 2151 2152 2153 2154 2155 2156 2157 2158 2159 2200

Benzene, 1,3-BD,ppb051015202530354045 Form aldehyde, ppbbenz_pidbud13_coform_coMe11, Houston Summer 20040510152025 1620 1622 1624 1626 1628 1630 1632 1634 1636 1638 1640 1642 1644 1646 1648 1650 1652 1654 1656 1658 1700

ppbvbenz_pidbud13_coform_coME12, Chicago Winter 200401234567

1616 1618 1620 1622 1624 1626 1628 1630 1632 1634 1636 1638 1640 1642 1644 1646 1648 1650 1652 1654 1656

ppbvbenz_pid13BD_coForm_coFigure 1.3.2-3. 1-Minute time series for out-of cabin outdoor exposures:ME8 (sidewalk);ME10 (surface parking); ME11(underground garage) and ME12 (toll plaza)cabin refueling;ME8:Out-of-cabin sidewalk;ME9: Out-of-cabin sidewalk/bus stop;ME10: Out-of-cabin surface parking;ME11: Out-of-cabin underground garage;ME12: Outside toll plaza;ME13:In-cabin trailing high-emitter vehicle1,3-Butadiane - No ME7 in Houstony = 1.1847x + 0.5092R2= 0.569502468101214024685-min Ave Surrogates

5-min Can10ME1In-cabin trailing hi



# 1-30: In-cabin congested freeway;ME2: In-cabin urban canyon;ME3: In-cabin refueling;ME4: In-cabin underground garage;ME5: In-cabin toll plaza;ME6: In-cabin roadway tunnel;ME7: Out-ofcabin refueling;ME8:Out-of-cabin sidewalk;ME9: Out-of-cabin sidewalk/bus stop;ME10: Out-of-cabin surface parking;ME11: Out-of-cabin underground garage;ME12: Outside toll plaza;ME13:gh-emitter vehicleFigure 1.3.2-4. Correlations between 5-minute canister samples and surrogate 1-minute values,averaged over corresponding 5minutes.Benzene - No ME7 in Houstony = 1.0955x - 2.7164R2= 0.87470501001502002503003504004505000 50 100 150 200 250 300 3505-Min Ave Surrogates

5-Min Can

# 1-31 1.3.3 Oxygenated and conventional gasoline (difference between cities)

The MTBE and EtOH concentration variability by ME in Houston and Chicago is shown

in Figure 1.3.3-1. The complete data are pr ovided in electronic form. Although MTBE is

measured in all Houston MEs, the concentrations recorded during refuelin g are relatively high, in

the range of a few ppmv. In cont rast, Chicago ethanol concentrati ons are lower, especially during

winter time. We generally use the same gas stat ion in each city (absent problems with the gas

station manager) and we select a station with high traffic close to a major freeway. For example,

the gas station in Houston was situated next to Tollway 8 and was always very busy.

The high concentrations of MTBE duri ng refueling in Houston caused occasional

problems with 1,3-BD quantification in canister samples as discussed at Section 1.3.1. In

addition, MTBE PID response changed the sl ope of canister ben zene and NMVOC PID

regressions in Houston MEs from those observed in Chicago and Atlanta, as shown in Table

1.3.2-1. However, when ME3 and ME7 data are rem oved from correlations, the slopes are more

consistent among the three cities.

Figures 1.3.3-2 and -3 show comparisons of average benzene, 1,3-BD, HCHO, and CO

concentrations by ME in the three cities by se ason. Tables 1.3.1-1 and 1.3.1-2 provide the data

for all species measured with the time-integr ated methods. For refueling MEs, the highest

benzene concentrations are observed in Hous ton, in both seasons. However, for underground

garage MEs, Atlanta shows the hi ghest concentrations of benzene, HCHO, and CO. It is however

not clear whether these findings result from the di fferent fuels, choice of specific ME locations,

or the greater variability of high- end ME exposures in general.ME1: In-cabin congested freeway;ME2: In-cabin urban canyon;ME3: In-cabin refueling;ME4: In-cabin underground garage;ME5: In-cabin toll plaza;ME6: In-cabin roadway tunnel;ME7: Out-of

# 1-32 ppbvHouston, Summer 2004MTBEME1ME2ME3ME4ME5ME6ME7ME8ME9ME10ME11ME120600120018002400300036004200480054006000MaximumMinimum75%25%MedianOutliersExtremes ppbvHouston, Winter 2005MTBEME1ME2ME3ME4ME5ME6ME7ME8ME9ME10ME11ME120600120018002400300036004200480054006000MaximumMinimum75%25%MedianOutliersExtremes

ppbvChicago, Summer 2003EthanolME1ME2ME3ME4ME5ME6ME7ME8ME9ME10ME11ME120153045607590105120MaximumMinimum75%25%MedianOutliersExtremes ppbvChicago, Winter 2004EthanolME1ME2ME3ME4ME5ME6ME7ME8ME9ME10ME11ME1201.534.567.5910.51213.5MaximumMinimum75%25%MedianOutliersExtremesFigure 1.3.3-1. MTBE and EtOH concentrationsin Houston and Chicago, respectively..Notedifferent y-axis scales for Chicago Sumerand Wintercabin refueling;ME8:Out-of-cabin sidewalk;ME9: Out-of-cabin sidewalk/bus stop;ME10: Out-of-cabin surface parking;ME11: Out-of-cabin underground garage;ME12: Outside toll plaza;ME13:In-cabin trailing high-emitter vehicleBenzene0204060801001201401 2 3 4 5 6 7 8 9 10 11 12 13

ppbvHoustonAtlantaChicago1,3-Butadiene01234567891 2 3 4 5 6 7 8 9 10 11 12 13

ppbvHoustonAtlantaChicagoME1: In-cabin congested freeway;ME2: In-cabin urban canyon;ME3: In-cabin refueling;ME4: In-cabin underground garage;ME5: In-cabin toll plaza;ME6: In-cabin roadway tunnel;ME7: Out-of

# 1-33Formaldehyde051015202530351 2 3 4 5 6 7 8 9 10 11 12 13

ppbvHoustonAtlantaChicagoCO02468101214161 2 3 4 5 6 7 8 9 10 11 12 13

ppmHoustonAtlantaChicagoFigure 1.3.3-2. Comparison of benzene, 1,3-BD, HCHO, and COaverage concentrations inthree cities in Summercabin refueling;ME8:Out-of-cabin sidewalk;ME9: Out-of-cabin sidewalk/bus stop;ME10: Out-of-cabin surface parking;ME11: Out-of-cabin underground garage;ME12: Outside toll plaza;ME13:In-cabin trailing high-emitter vehicleME1In-cabin trailing hi



# 1-34: In-cabin congested freeway;ME2: In-cabin urban canyon;ME3: In-cabin refueling;ME4: In-cabin underground garage;ME5: In-cabin toll plaza;ME6: In-cabin roadway tunnel;ME7: Out-ofcabin refueling;ME8:Out-of-cabin sidewalk;ME9: Out-of-cabin sidewalk/bus stop;ME10: Out-of-cabin surface parking;ME11: Out-of-cabin underground garage;ME12: Outside toll plaza;ME13:gh-emitter vehicleBenzene01020304050600 1 2 3 4 5 6 7 8 9 10 11 12 13M E

ppbvAtlantaChicagoHouston1,3-Butadiene0246810120 1 2 3 4 5 6 7 8 9 10 11 12 13ME

ppbvAtlantaChicagoHoustonFormaldehyde05101520250 1 2 3 4 5 6 7 8 9 10 11 12 13ME

ppbvAtlantaChicagoHoustonCO051015200 1 2 3 4 5 6 7 8 9 10 11 12 13ME

ppmAtlantaChicagoHoustonFigure 1.3.3-3. Comparison of benzene, 1,3-BD, HCHO, and COaverage concentrations inthree cities in Winter

# 1.3.4 Effect of meteorology on exposure

As shown in Figures 1.3.3-1 through 1.3.3-6 the hi ghest day-to-day variations in in-cabin

or out-of-cabin exposures occur during refueling, in ME3 and ME7. ME4 and ME11 relate to

exposures in an underground garage so these MEs are not subject to different meteorological

conditions. However, wind speed an d direction play an important role in refueling MEs. As a

general rule, we performed refueling expe riments under calm conditions (wind speeds ≤ 4 mph).

Also, it was usually possible to fi nd a pump location that was relativ ely sheltered from the direct

influences of the wind. Subjects generally stood downwind during refueling tests. As a result,

correlations of wind speed and c oncentrations in the refueling MEs were weak. For example,

summer ME7 BTEX levels were highest in Chicago with a steady wind speed of 2-3 mph and

lowest at variable wind speeds of 1-3 mph.

Table 1.3.4-1 lists average outdoor ambient te mperatures and relative humidity by ME,

city, and season. The detailed data recorded dur ing each test are provided in electronic form.

Table 1.3.4-1. Average, minimum, and ma ximum ambient temperatures and RH

Temperature ( oC) RH (%) City Season ME Replicate

ave min max ave min max

A S 1 5 27.6 27 29 58.4 56 60

A S 2 3 24.3 22 27 42.6 33 63

A S 3 5 32.0 26 37 61.8 44 74

A S 4 5 32.2 31 33 52.2 46 61

A S 5 3 24.2 22 26 49.9 36 72

A S 7 5 29.5 22 34 63.0 57 86

A S 8 3 33.7 29 39 41.0 29 65

A S 9 3 33.7 29 39 41.0 29 65

A S 10 3 31.9 22 41 42.6 20 69

A S 11 5 33.2 32 35 47.8 42 51

A S 12 3 27.1 24 32 58.8 42 77

A S 13 5 41.2 37 46 49.4 47 54

C S 1 5 27.0 26 28 52.2 46 55

C S 2 3 25.0 24 26 45.7 42 49

C S 3 6 30.5 24 35 51.8 45 63

C S 4 5 26.4 23 28 60.8 56 66

C S 5 3 29.7 26 33 56.7 54 61

C S 6 5 30.0 29 31 53.4 50 57

C S 7 5 28.6 24 31 59.0 50 68

C S 8 3 25.0 23 27 55.0 54 56

C S 9 3 26.3 25 28 53.3 51 55

C S 10 3 21.0 20 23 70.3 67 73

C S 11 5 28.4 22 33 56.6 46 67

C S 12 3 31.7 30 34 43.0 31 57

H S 1 5 33.8 30 37 55.6 51 63



# 1-35

## Temperature ( oC) RH (%) City Season ME Replicate

ave min max ave min max

H S 3 5 36.8 30 41 48.6 42 59

H S 4 5 31.0 30 33 43.0 37 53

H S 5 3 29.3 29 30 56.0 54 58

H S 6 5 37.8 32 42 51.0 48 57

H S 7 5 36.6 29 40 54.0 48 70

H S 8 3 31.0 28 33 59.3 42 76

H S 9 3 31.7 28 34 59.3 49 78

H S 10 3 36.0 27 53 58.0 40 69

H S 11 5 31.8 27 35 49.6 41 59

H S 12 3 30.0 30 30 68.0 66 70

A W 1 5 12.2 4 27 35.4 21 49

A W 2 3 10.0 7 13 33.0 29 37

A W 3 5 11.8 7 18 40.8 29 56

A W 4 5 15.2 9 19 42.0 30 47

A W 5 3 13.3 7 17 31.0 27 34

A W 7 6 10.7 7 17 55.8 42 82

A W 8 3 3.7 1 6 64.3 45 76

A W 9 3 3.7 1 6 63.3 45 73

A W 10 3 10.3 7 15 52.7 38 64

A W 11 5 15.4 8 21 47.8 27 64

A W 12 3 9.3 6 15 55.7 22 77

A W 13 5 14.2 4 26 37.2 23 50

C W 1 5 7.0 0 12 19.8 10 26

C W 2 3 6.7 4 9 24.0 21 26

C W 3 5 6.3 4 11 22.0 14 32

C W 4 5 11.4 13 16 30.2 26 60

C W 5 3 7.0 3 10 18.0 13 22

C W 6 5 6.8 3 10 25.0 14 42

C W 7 5 6.9 2 9 27.0 32 63

C W 8 3 4.7 1 9 46.7 32 63

C W 9 3 6.3 2 12 43.3 28 61

C W 10 3 6.0 1 9 37.3 32 42

C W 11 5 13.6 11 15 42.0 30 62

C W 12 3 2.0 0 5 53.7 25 78

H W 1 5 14.8 9 24 41.6 30 59

H W 2 3 14.7 9 21 37.3 34 43

H W 3 5 16.2 10 23 52.8 38 62

H W 4 5 15.6 10 19 54.4 36 69

H W 5 3 15.0 8 20 49.7 44 56

H W 6 5 22.4 14 25 46.6 34 55

H W 7 5 15.8 10 22 67.6 56 77

H W 8 3 9.7 7 12 61.0 53 71

H W 9 3 11.7 8 15 56.0 47 67

H W 10 3 16.3 14 21 63.3 48 76

H W 11 5 15.4 9 19 69.8 43 87

H W 12 3 15.0 8 20 78.0 70 83



# 1-36

# 1-37 1.3.5 Comparison of summer and winter exposures

Figures 1.3.5-1 through 1.3.5-3 shows the differe nces between exposures in each city

during the summer and winter seasons. For Chic ago, the concentrations of benzene, 1,3-BD, and

CO are higher in the underground garage (ME4 and ME11) during winter season. The same is

true for ME3 and ME7, although CO concentrations are low and comparable for these refueling

MEs, as expected. However, HCHO is clearly higher during the summer season in all MEs,

perhaps a result of photochemical formation of this compound. In Houston, benzene is clearly

much higher in refueling MEs in summer. Howe ver, for ME4 and ME11, winter concentrations

are also marginally higher for benzene, 1,3-BD and CO. HCHO is less consistent, but clearly

higher in summer in outdoor MEs (8, 9, 10, and 12). For Atlanta, the differences are not very

large between winter and summer seasons, and not very consistent between different species and

MEs. However, HCHO is clearly higher in summer in outdoor MEs (7, 8, 9, 10, and 12).Atlanta, 1,3-Butadiane0123450 1 2 3 4 5 6 7 8 9 10 11 12 13ME

ppbv1,3-BD_S1,3-BD_WAtlanta, Benzene010203040500 1 2 3 4 5 6 7 8 9 10 11 12 13ME

ppbvBenzene_SBenzene_WME1: In-cabin congested freeway;ME2: In-cabin urban canyon;ME3: In-cabin refueling;ME4: In-cabin underground garage;ME5: In-cabin toll plaza;ME6: In-cabin roadway tunnel;ME7: Out-of

# 1-38Atlanta, Formaldehyde051015202530350 1 2 3 4 5 6 7 8 9 10 11 12 13ME

ppbvFormal_SFormal_WAtlanta, CO051015200 1 2 3 4 5 6 7 8 9 10 11 12 13ME

ppmvCO_SCO_WFigure 1.3.5-1. Time integrated averageexposure levels in different MEs inAtlanta in Summer and Winter season.cabin refueling;ME8:Out-of-cabin sidewalk;ME9: Out-of-cabin sidewalk/bus stop;ME10: Out-of-cabin surface parking;ME11: Out-of-cabin underground garage;ME12: Outside toll plaza;ME13:In-cabin trailing high-emitter vehicleME1: In-cabin congested freeway;ME2: In-cabin urban canyon;ME3: In-cabin refueling;ME4: In-cabin underground garage;ME5: In-cabin toll plaza;ME6: In-cabin roadway tunnel;ME7: Out-of

# 1-39Chicago, Benzene05101520250 1 2 3 4 5 6 7 8 9 10 11 12 13ME

ppbvBenzene_SBenzene_WChicago, 1,3-Butadiane0123450 1 2 3 4 5 6 7 8 9 10 11 12 13ME

ppbv1,3-BD_S1,3-BD_WChicago, CO024681012140 1 2 3 4 5 6 7 8 9 10 11 12 13ME

ppmvCO_SCO_WChicago, Formaldehyde0246810121416180 1 2 3 4 5 6 7 8 9 10 11 12 13ME

ppbvFormal_SFormal_WFigure 1.3.5-2. Time integrated averageexposure levels in different MEs inChicago in Summer and Winter seasoncabin refueling;ME8:Out-of-cabin sidewalk;ME9: Out-of-cabin sidewalk/bus stop;ME10: Out-of-cabin surface parking;ME11: Out-of-cabin underground garage;ME12: Outside toll plaza;ME13:In-cabin trailing high-emitter vehicleHouston, 1,3-Butadiane012340 1 2 3 4 5 6 7 8 9 10 11 12 13ME

ppbv1,3-BD_S1,3-BD_WHouston, Formaldehyde0246810120 1 2 3 4 5 6 7 8 9 10 11 12 13ME

ppbvFormal_SFormal_WME1In-cabin trailing hi



# 1-40: In-cabin congested freeway;ME2: In-cabin urban canyon;ME3: In-cabin refueling;ME4: In-cabin underground garage;ME5: In-cabin toll plaza;ME6: In-cabin roadway tunnel;ME7: Out-ofcabin refueling;ME8:Out-of-cabin sidewalk;ME9: Out-of-cabin sidewalk/bus stop;ME10: Out-of-cabin surface parking;ME11: Out-of-cabin underground garage;ME12: Outside toll plaza;ME13:gh-emitter vehicleFigure 1.3.5-3. Time integrated averageexposure levels in different MEs inHouston in Summer and Winter seasonHouston, CO02468100 1 2 3 4 5 6 7 8 9 10 11 12 13ME

ppmvCO_SCO_WHouston, Benzene0204060801001201400 1 2 3 4 5 6 7 8 9 10 11 12 13ME

ppbvBenzene_SBenzene_W

# 1-41 1.3.6 Correlations to breath concentrations

Figures 1.3.6-1 and 1.3.6-2 show s the average concentrations of BTEX, 1,3-BD, MTBE,

EtOH and CO 2 

# measured in pre- and a pos t-peak exposure breath for th ree MEs in each city and

season. Detailed data are submitted in the electronic form. As it can be seen from these figures, a

considerable increase in concentr ations of measured species occurs in all cases immediately after

a peak exposure. In Atlanta and Chicago, the high est breath concentrations of BTEX and 1,3-BD

were observed in ME7 (refueling) and ME 11 (underground garage). In Houston, high

concentrations of MTBE were measured in ME7 in summer and winter. Although high

concentrations of EtOH were measured in breath in all Chicago MEs, it is not clear if this is due

wholly to the presence of EtOH in Chicago fuel, since pre-exposure breath concentrations were

occasionally higher than the post-exposure con centrations. Subjects were cautioned against

consuming alcoholic beverages or using alcoholic personal care products prior to breath testing

but EtOH may also be a metabolic product for certain other food types. For example, it has been

reported (Turner et al., 2006) that increased ethanol levels were obs erved in the breath of healthy

individuals if sweet drinks/f ood had been consumed within 2 hr prior to providing breath

samples.

Figure 1.3.6-3 (upper panel) shows the co rrelations between 1-minute maximum

surrogate values for benzene and 1,3-BD and pos t-exposure breath con centrations of these

species. The correlation is so mewhat better for 1,3-BD (R 2 

# = 0.46) than for benzene (R 2 

# = 0.26);

however, benzene concentrations in these MEs are much higher than breath concentrations. As

shown in the lower panel of Figure 1.3.6-3, both benzene and 1,3-BD concentrations in breath

track well these compound concentra tions in all MEs. Note that the logarithmic scale was used

for benzene and that no ME3 and ME7 data were included in 1,3-BD correlations for Houston.

Also, some 1-minute surrogate 1,3-BD and benz ene values are missing for certain MEs. As

explained in Section 1.3.2, if the CO or NMVOC values were below the approximate detection

limits of the continuous CO and PID instrume nts (0.5 ppmv and 25 ppbv, respectively), no 1-min

surrogate data were calculated. Data used fo r these plots are submitted in electronic form.ME1: In-cabin congested freeway;ME2: In-cabin urban canyon;ME3: In-cabin refueling;ME4: In-cabin underground garage;ME5: In-cabin toll plaza;ME6: In-cabin roadway tunnel;ME7: Out-ofcabin refueling;ME8:Out-of-cabin sidewalk;ME9: Out-of-cabin sidewalk/bus stop;ME10: Out-of-cabin surface parking;ME11: Out-of-cabin underground garage;ME12: Outside toll plaza;ME13:



# 1-42Atlanta, Summer 200301020304050ME7pre ME7post ME11pre ME11post ME13pre ME13post

ppbv0123456 % CO2bud13benzetolueetbzmp_xylo_xylCO2 %Chicago, Summer 20030246810121416ME6pre ME6post ME7pre ME7post ME11pre ME11post

ppbv0123456 % CO2bud13benzetolueetbzmp_xylo_xylCO2%Houston, Summer 20040100200300400500600ME6-pre ME6-postME11-preME11-postME7-pre ME7-post

ppbv012345 % CO2bud13mtbebenzetolueetbzmp_xylo_xylCO2 (%)0510152025ME6-pre ME6-post ME11-pre ME11-post

ppbv012345 % CO2Chicago, Summer 200302468101214ME6pre ME6post ME7pre ME7post ME11pre ME11post

BTEX, ppb020406080100120140

EtOH, ppbBTEXEtOHFigure 1.3.6-1. Average breath BTEX, 1,3-BD, MTBE, EtOH, and CO2 concentrations inthree cities in SummerIn-cabin trailing high-emitter vehicleME1: In-cabin congested freeway;ME2: In-cabin urban canyon;ME3: In-cabin refueling;ME4: In-cabin underground garage;ME5: In-cabin toll plaza;ME6: In-cabin roadway tunnel;ME7: Out-ofcabin refueling;ME8:Out-of-cabin sidewalk;ME9: Out-of-cabin sidewalk/bus stop;ME10: Out-of-cabin surface parking;ME11: Out-of-cabin underground garage;ME12: Outside toll plaza;ME13:



# 1-43Atlanta, Winter 2004051015202530354045ME7-pre ME7-post ME11-pre ME11-post ME13-pre ME13-post

ppbv1234567 CO2 %budi13benzetolueetbzmp_xylo_xylCO2_percenChicago, Winter 200405101520253035ME6-pre ME6-post ME7-pre ME7-post ME11-pre ME11-post

ppbv1234567 CO2 %budi13benzetolueetbzmp_xylo_xylCO2_percenHouston, Winter 2005020406080100120ME6-pre ME6-post ME11-pre ME11-post ME7-pre ME7-post

ppbv0123456 CO2 %budi13benzetolueetbzmp_xylo_xylmtbeCO2_percen024681012141618ME6-pre ME6-post ME11-pre ME11-post

ppbv0123456 CO2 %Chicago, Winter 2004051015202530ME6-pre ME6-post ME7-pre ME7-postME11-pre ME11-post

BTEX, ppbv050100150200250300350400450 EtOH, ppbvBTEXEtOHFigure 1.3.6-2. Average breath BTEX, 1,3-BD, MTBE, EtOH, and CO2 concentrations inthree cities in WinterIn-cabin trailing high-emitter vehicle1,3-Butadianey = 0.6102x + 0.1788R2= 0.46120246810120 2 4 6 8 10 12 141-min max

Peak Breath1,3-Butadiane02468101214 AS11B_1B AS11B_3B AS13B_1B AS13B_5B AW11B_2B AW11B_4B AW13B_1B CS06B_1B CS06B_3B CS11B_2B CS11B_4B CW06B_1B CW06B_3B CW06B_5B CW11B_1B CW11B_4B HS06B_1B HS06B_3B HS06B_5B HS11B_2B HS11B_4B HW06B_1B HW06B_3B HW06B_5B HW11B_3B HW11B_5B

1-Min Max024681012 Breath1,3-BD_1min1,3-BD_breathME1In-cabin trailing hi



# 1-44: In-cabin congested freeway;ME2: In-cabin urban canyon;ME3: In-cabin refueling;ME4: In-cabin underground garage;ME5: In-cabin toll plaza;ME6: In-cabin roadway tunnel;ME7: Out-ofcabin refueling;ME8:Out-of-cabin sidewalk;ME9: Out-of-cabin sidewalk/bus stop;ME10: Out-of-cabin surface parking;ME11: Out-of-cabin underground garage;ME12: Outside toll plaza;ME13:gh-emitter vehicleFigure 1.3.6-3. Correlations between 1-minutesurrogate benzene and 1,3-BD max valuesand post-exposure breath concentrations(upper panel) and comparison of these concentrations in different ME andcities (lower panel)Benzene0110100100010000 AS07M_1 AS07M_3 AS07M_5 AS11M_2 AS11M_4 AS13M_1 AS13M_5 AW07M_2 AW07M_4 AW07M_6 AW11M_2 AW11M_4 AW13M_1 AW13M_3 AW13M_5 CS06M_2 CS06M_4 CS07M_2 CS11M_2 CS11M_4 CW06M_5 CW07M_4 CW11M_1 CW11M_4 HS06M_2 HS06M_4 HS07M_1 HS07M_3 HS07M_5 HS11M_3 HS11M_5 HW06M_2 HW06M_4 HW07M_1 HW07M_3 HW07M_5 HW11M_3 HW11M_5benz_1minbenz_breathBenzeney = 0.0105x + 4.7492R2= 0.231405101520253035400 500 1000 1500 2000 25001-min max

Peak Breath

# 1.4 Conclusions

Summary findings related to the th ree city study are as follows:

• Day-to-day variations in high-end (99+ th 

# percentile) benzene, 1,3-BD, HCHO, and

CO concentrations in different MEs are substantial and independent of city and

season, but related to the activity and emi ssion rates of sources in the given MEs

which differ from day to day.

• With the exception of refueling, exposure le vels are generally lower in outdoor MEs

and higher in enclosed MEs.

• The 20-min average refueling benzene e xposures range up to few hundred ppbv and

show substantial day-to-day variability.

• In-cabin exposures during on-road vehicle op eration are more consistent and uniform

than for other in-cabin MEs.

• BTEX species show the highest concentr ations in refueling MEs dominated by

evaporative emissions whereas CO, HCHO, and 1,3-BD are the highest in the coldstart dominated MEs.

• BTEX and 1,3-BD measured by time-i ntegrated canister method show good

correlations with continuous NMVOC a nd CO measurements, respectively. HCHO

correlation with continuous CO is modest, probably due to photochemical production

of this compound.

• Continuous NMVOC (PID) and CO (NDIR) data can be used to reconstruct 1-minute

time series for benzene and 1,3-BD, resp ectively, provided that the averaged

continuous measurements are above the det ection limits of the instruments (25 ppbv

and 0.5 ppmv, respectively). CO data can also be used to reconstruct 1-minute HCHO

data; however, less reliably so due to poorer correlation between these species.

• Reconstructed 1-minute time-series data fo r benzene and 1,3-BD, averaged over the

five minute time frame corresponding to the collection of 5-minut e canister samples,

correlate well after excluding the Houston refueling ME with relatively high TVOC

levels that distort typical correlation coefficients and el evated MTBE levels which

bias 1,3-BD measurements.

• The concentrations of benzene and 1,3-BD measured in post p eak exposure breath

samples track corresponding ME 1-minute ma ximum reconstructed surrogate values

well.

• Increases in concentrations of measured sp ecies occur in all breath samples collected

within a minute of a peak exposure. In Atlanta and Chicago, the highest breath

concentrations of BTEX and 1,3-BD were observed in ME7 (refueling) and ME11

(underground garage), respect ively. In Houston, high concen trations of MTBE were

measured in ME7.

• The largest differences in benzene, 1,3-BD , and CO concentrations between summer

and winter seasons are observed in Chi cago, consistent with the largest ambient

temperature differences for this city. Thes e concentrations are higher in winter. For

Atlanta and Houston such differences are less pronounced. HCHO is consistently

higher in summer season in outdoor environm ents, probably due to the photochemical

production of this compound.

1-45

# 1.5 References

Batterman, S. S, Peng C-y, Braun, J. (2002). Levels and composition of volatile organic

compounds on commuting routes in Detroit, Michigan. Atmos. Environ., 36 :6013-6030.

Chan, C-C., H. Ozkaynak, J. D. Spengler and L. Sheldon (1991). Driver exposure to volatile

organic compounds, CO ozone, NO2 under different driving conditions. Environ. Sci.

Technol., 25 : 964-972.

Fedoruk, M.J. and Kerger, B.D. (2003). Measurem ents of volatile organic compounds inside

automobiles. Journal of Exposure Analysis and Environmental Epidemiology

, 13 :31-41

Lindstrom A.B. and J.D. Pleil (1996). Alve olar Breath Sampling a nd Analysis to Assess

Exposures to Methyl Tertiary Butyl Ether (MTBE) During Motor Vehicle Refueling. J.

Air & Waste Manage. Assoc

., 46 :676-682.

Pleil, J. D.and A. Lindstrom (2002). A review of the USEPA’s single breath canister (SBC)

method for exhaled volatile organic biomarkers. Biomarkers

, 7 :189-208.

Rodes, C., L. Sheldon,, D. Whitaker, et al., (199 8). Measuring Concentrations of Selected Air

Pollutants Inside California Vehicles. Fina l report, ARB Contract # 95-339. California

Air Resources Board.

Turner, C., P. Spanel and D. Smith (2006). A l ongitudinal study of ethanol and acetaldehyde in

the exhaled breath of healt hy volunteers using selected-i on flow-tube mass spectrometry.

Rapid Commun. Mass Spectrom.

, 20 :61-68.

Vayghani, S. A. and C. Weisel (1999). The MTBE air concentrations in th e cabin of automobiles

while fueling. Journal of Exposure Analysis and Environmental Epidemiology

, 9 :261-

267.

Weisel, C., N. J. Lawryk, P. J. Lioy (1992). Ex posure to emissions from gasoline within

automobile cabins. J. Expo Anal Environ Epidem

, 2 (1):79-96.

Zielinska, B., E. Fujita, J. Sagebiel, G. Harshf ield, E. Uberna, T. Hayes, and F. Keene (1998).

Arizona Hazardous Air Pollutants Monitoring Program. J. Air Waste Manage. Assoc.,

48 :1038-1050.

Zielinska, B., E. M. Fujita, J.C. Sagebiel, D. E. Campbell, L.R. Smith, T. Johnson (2003a).

Exposure Protocol and Study Plan for the Section 211 (B) Tier 2 High End Exposure

Screening Study of Baseline and Oxygenated Gasoline. Prepared for American Petroleum

Institute, 1220 L Street, Washington, DC 20005-4007. Final Version. October 1, 2003.

Zielinska, B, E.M. Fujita, and J.C. Sagebiel (2003b). Section 211 (B) Tier 2 High End Exposure

Screening Study of Baseline and Oxygenated Gasoline-Summer 2002 Atlanta Field Study

on Baseline Gasoline. Prepared for Ameri can Petroleum Institute, 1220 L. Street,

Washington, DC 2005-4070. March 13, 2003.

Zielinska, B, J.C. Sagebiel, D.Campbell and E. M. Fujita, (2004a). Section 211 (B) Tier 2 High

End Exposure Screening Study of Baselin e and Oxygenated Gasoline-Summer 2003

Chicago and Atlanta Field Study on Baseline Ga soline. Prepared for American Petroleum

Institute, 1220 L. Street, Wa shington, DC 2005-4070. March 13, 2003.

1-46

# 2. Relative Contributions of Vehicle Ev aporative and Exhaust Emission to

Concentrations of Volatile Air Toxics in High Exposure

Microenvironments in Houston

2.1 Introduction

The Desert Research Institute (DRI) conducte d measurements to quantify exposures to

automotive emissions in microenvironm ents representing the upper-end (> 99 th 

# percentile) of the

distribution of inhalation exposur es to evaporative and exhaust emissions of conventional- and

oxygenated-gasoline. The study was conducted as pa rt of the Section 211(b) Tier 2 High-End

Exposure Study of Conventional and Oxygena ted Gasoline. DRI and SwRI conducted

measurements under controlled conditions to es tablish quantitative relationships between tailpipe

and evaporative emission rates to exposure levels in a vehicle cabin a nd attached residential

garage. Field exposures also were measured in several high-end exposure microenvironments in

Atlanta, Chicago, and Houston during winter and summer. Target species (TVOC, CO, BTEX,

HCHO,1,3-BD, MTBE, EtOH) were measured with in microenvironments, breathing zones, and

breath. This section apportions the relative contributions of fu el combustion and evaporative

emissions to exposures measured various high-end microenvironments, based on differing

abundances of MTBE and benzene in exhaust and ev aporative emissions. This particular analysis

approach was applied to the exposure data from Houston because it is th e only city included in

the Section 211(b) exposure screening study to use MTBE as the oxygenated additive.

Federal reformulated gasoline (RFG) was intr oduced in 1995 in ni ne metropolitan areas

of the United States that were not in attainment of the ambient air quality standard for ozone. The

RFG program is implemented year-round in thes e areas as an emission reduction program to

control ambient ozone and m obile source air toxics (MSA T). Non-oxygenated conventional

gasoline was used in Atlanta during the pe riod of study. Ethanol wa s used to oxygenate

reformulated gasoline in Chicago and MTBE in the Houston area. Table 2-1 summarizes the

major differences in fuel composition between conventional and RFG. Exhaust emissions

include a mixture of un-combusted fuel co mponents (e.g., BTEX, MTBE, EtOH, TVOC) and

species produced during combustion (e.g., be nzene, 1,3-BD, HCHO, CO). The relative

abundances of combustion by-produ cts in the exhaust profile vary with emission control

technology, level of vehicle main tenance, and operating mode.

Liquid gasoline contains many target compounds (BTEX, MTBE, EtOH, TVOC) in

common with gasoline-vehicle exhaust. Gasolin e headspace vapor, vapor in equilibrium with

liquid gasoline, also contains these combustion compounds but is enriched in the more volatile

species such as benzene, MTBE, and EtOH. Composite liquid and h eadspace vapor profiles

across different brands and grades of gasoline were developed in conjunction with the Tuscarora,

Fort McHenry, and SOS on-road exhaust experiments, for the Auto-Oil program, COAST, the

Paso del Norte Study, and the 1995/96 RFG Study (Zielinska et al., 1997). Gasoline

compositions were also determine for western Wash ington (Fujita et al., 1997c), Austin (Fujita,

et al. 1999a), San Francisco Bay Area (Kirchstette r et al., 1999), Houston (Fujita et. al., 2001),

and Los Angeles (Fujita et al, 1997; Fujita et al., 2003).

2-1

# There are several sources of evaporative emissions including hot soak emissions driven

by residual engine heat following cessation of ve hicle operation, diurnal emissions associated

with fuel tank ‘breathing’ during diurnal temperature and barometric pressure cycling, running

losses resulting from fuel tank radiant heating by roadways or from injector fuel recirculation

during vehicles operation, rest ing losses from gasoline permea tion through rubber and plastic

components of the fuel lines, and simple fuel system leakage. From an analysis of ambient air

samples and reconciliation with VOC source profile s, Pierson et al. (199 9) conclude that 71 ±

9% of motor vehicle VOC emissions are emitted from tailpipes, 17 ± 6% result from non-tailpipe

liquid fuel emissions (fuel system leakage) , a nd 12 ± 4% are due to headspace vapor emissions.

2.2 Experimental Approach

The profiles for vehicle exhaust, liquid gaso line, and gasoline head space vapor include

many of the same species but notable differences in the ratio of species, a difference that can be

used to apportion tailpipe and evaporative em ission source strengths. Th e proportion of MTBE in

exhaust is reduced during combus tion relative to its pr oportion in the fuel. Conversely, benzene

is enriched in exhaust relative to its proportion in the fuel due to toluene and xylene dealkylation.

Consequently, MTBE to benzene ratios are substan tially lower in exhaust than in liquid fuel or

headspace vapors. MTBE and benzene were measur ed in all microenvironments in Houston as

well as in fuel and vehicle exhaust samples. The fractional evaporativ e contribution, X, was

estimated using following formula.

X = (R ME 

# - R EXH 

# )/ (R VAP 

# - R EXH 

# )

R ME 

# is the measured microenvironmental MTBE/benzene ratio, R EXH 

# is the exhaust

MTBE/benzene ratio, and R VAP 

# is the evaporative MTBE/benzene vapor ratio; either of whole

gasoline or headspace vapor depending upon type of evaporative emissions expected in a

particular ME (e.g., whole liquid gasoline for hot soak, leaks, or spills and headspace vapors if

refueling). Some MEs are influenced by a comb ination of whole gasolin e and headspace vapor

emissions.

For the present study, the Southwest Research In stitute (SwRI) procured two test vehicles

and determined their evaporative/tailpipe emissions in the normal/malfunction modes using the

three test fuels. The test vehi cles, a sedan and full-sized V8 truck, were chosen within the 1993-

1996 model years from vehicles with 90,000-110,000 odometer miles. The chosen 1993 Toyota

Camry (2.2L 4-cylinder engine) and 1995 Ford F150 Pickup truck (5.0L V8 engine) were

operated in normal, as purchased, modes and in “high emitter” modes with the catalytic

converter removed and emission levels above 2 grams per mile NMHC as measured on the FTP

driving cycle. While converter removal sufficed for the F150 truck, a calibrated manifold leak

was also needed to achieve the ≥ 2g/mile Camry emissions. SwRI determined dynamometer FTP

emissions for each vehicle with all three fuels in the two emission modes (24 tests). Emission

control components could be repr oducibly adjusted to represent normal and reasonable high-end

approximations ( ≥ 2g/mile) of real world exhaust emissions.

The FTP exhaust emission test uses the 1372 second Urban Dynamometer Driving

Schedule (UDDS) that is divided into cold/start tran sient 505 (Bag 1) and cold stabilized 867

2-2

# (Bag 2) second segments. This portion of the FT P is followed by a 10-minute soak and a hot/start

transient 505 (Bag 3) test. The FTP evaporativ e emission test includes one hour Diurnal Heat

Build (DHB) and Hot Soak Loss (HSL) tests. TH C/VOC emissions are recorded during the HSL

segment of the test. Prior to the FTP cold-start exhaust test, the DHB is conducted by fueling the

test vehicle to 40 percent of tank capacity with fuel < 55°F, attaching a heating blanket outside

the fuel tank, placing a thermocouple in the tank fuel, hooking it up to computer control, and

beginning the test as fuel reaches 60°F (increasin g at 0.4°F per minute for the 60-minute test to a

84°F final temperature). In the HSL segmen t, conducted immediately following exhaust

emission testing, the vehicle is driven into an evaporative emission enclosure and allowed to

“soak” in the enclosure for one hour. THC/VOC emissions are m easured at the beginning and

end of the one-hour segment and hot soak evaporative emissions are calculated.

Test fuel samples were subject to standa rd tests for Reid Vapor Pressure (RVP),

distillation range, Specific Gravity, Sulfur, Benzene, HC Category (s aturates, olefins, aromatics),

Oxygenated species (MTBE/EtOH) , carbon weight percent, hydr ogen weight percent, oxygen

weight percent, and octane number. Gasoline he adspace vapor compositions were predicted from

the measured composition of liquid gasoline using the Raoult’s Law method described by

Kirchstetter et al. (1999). This method is based on the proportionality between the compound

headspace partial pressure and its liquid mole fraction times the vapor pressure of the pure

species. The individual vapor pr essures are determined using th e Wagner equation (Reid et al.

1987).

DRI measured seasonal in-cabin breathing z one exposures for urban roadways and other

high-end MEs in Houston (6/3-7/9/04; 2/1-2/8/05), Chicago (8/5-8/20/03; 3/3-3/17/04), and

Atlanta (7/28-8/8/02; 8/23-9/3/03 ; 2/10-2/29/04) using a combinat ion of time-integrated samples

and continuous instruments listed in Table 2- 2. Three replicate exposure measurements were

made for low variability MEs and five for MEs with higher variability (i.e., ME13-trailing high

emitting vehicles, ME11-underground garages, a nd ME7-outdoor refueling). Measurements in

each ME were taken over a period of 20-40 minute s beginning at the top of the hour. Shorter

sampling times were used for refueling events a nd parking garage exits after sporting events.

Sampling and analytical methods ar e described in Section 1 of the report and in the study plan

(Zielinska et al., 2003).

2.3 Results

The measured MTBE/benzene ratios are summar ized in Table 2-3 for the Houston MEs.

Exposures at the two refueling MEs (3 & 7) were dominated by evaporative emissions as

expected, with MTBE/benzene ratios of 20 to 30. Ratios for all other MEs were between 1 and 4.

The exhaust, headspace, and liquid fuel MTBE/ben zene ratios measured in this and other recent

studies are shown in Table 2-4. MTBE/benzen e exhaust ratios among the dynamometer tests

average slightly less than 1 with the tunnel ratios nearer 2, possi bly due to the added running loss

emissions in tunnels. The MTBE/benzene ratios in liquid gasoline and vapor are similar,

averaging 15-20. Ratios for the SwRI SHED tests vary somewhat with calculated headspace

compositions and values from earlier listed studies.

2-3

# The estimated fractional contributions of eva porative emissions to total motor vehicles

emissions for the various Houston MEs, using the above method, are summarized in Table 2-5

and Figure 2-1. Uncertainties are the standard deviat ion of the ratios calculated from replicate

test measurements for each ME (represents the vari ability of ratio within observed sample set).

Exposures during refueling (ME3, ME7) are 100 % due to evaporative emissions within the

uncertainties associated with the measuremen ts and method. All other MEs are dominated by

tailpipe emissions with fractiona l evaporative cont ributions < 10%.

2.4 Conclusions

The results presented in Table 2-5 indicate th at evaporative emissions are only substantial

components of high end ME exposures during ve hicle refueling operations, where they are

dominant. Since refueling MEs have the highest relative levels of these components (see sections

1 and 3), they constitute the peak exposures, although overall the averag e population time spent

in these high end MEs is likely the shortest. The contribution of evaporative emissions for all

other MEs was typically about 5% of the total measured exposure. Results were similar for both

seasons, although evaporative contributions dur ing refueling were ma rginally less during

summer, possibly due to more rapid dispersion of vapors and evaporation of fuel spilled during

each refueling test at higher summer temperat ures. The clear distinction in evaporative

contribution between refueling and non-refuelin g MEs, along with the re lative consistency in

MTBE/benzene ratios shown in Table 2.4, give s some confidence in the approach.

These results suggest that the contemporary H ouston vehicle fleet c ontains relatively few

carbureted or leaking vehicles gi ven that evaporative emissions ar e not a substantial source in the

non-refueling MEs tested. Refueling emissions re leased from pressurized fuel systems and

spilled fuels appear to be th e primary source of peak evapor ative exposures. The lack of a

seasonal variability in the evaporative contribut ion is also consistent with this supposition.

Although it was not feasible to tr y to distinguish further betw een liquid and headspace vapor

contributions by the method used, the extremel y low MTBE/benzene ratios observed for the

roadway, sidewalk, and parking ME s suggest that the contributions of emissions from leaking

liquid gasoline is relatively small.

The contributions of exhaust and evaporative em issions to ambient volatile air toxics were

estimated for Houston only since it is the only city among the three in the study with oxygenated

gasoline containing MTBE. While the contributions of evaporative emissions relative to exhaust

emissions may vary with differences in aver age prevailing meteorological conditions, such

differences are unlikely to result in significantly different conclusions in other cities with regard

to the relative contributio ns of exhaust and evaporative emissi ons to ambient concentrations of

volatile air toxics. It must also be noted that the vehicle used in this study for the refueling tests

was a 1996 vehicle. All vehicles prior to the 1998 model year do not have onboard refueling

vapor recovery (ORVR) systems, and therefor e higher refueling emissions. Although refueling

stations in Houston had Stage II vapor recovery systems, the ORVR system also reduces vapor

losses when the fuel cap is opened by lowering the internal pressure of the fuel tank. The

implementation of ORVR systems may further re duce the relative contribu tions of evaporative

emissions.

2-4

# Table 2-1. Conventional gasoline versus refo rmulated gasoline RF G (from EPA OTAQ web

page http://www.epa.gov/OMSWWW/rfgnew.htm, updated by S. Romanow, OTAQ).

Fuel Parameter Values (national basis)

Conventional Gasoline Gasohol Oxyfuel

(2.7% wt) "Summer"

Phase I RFG

Average a 

## Range b 

## Average Average Average e



## 8.7-S 6.9-15.1 9.7-S 8.7-S 7.0-7.9 f



## 11.5-W 11.5-W 11.5-W

T50 (°F) 207 141-251 202 205 199

T90 (°F) 332 286-369 316 318 325

Aromatics (volume %) 28.6 6.1-52.2 23.9 25.8 22.3

Olefins (volume %) 10.8 0.4-29.9 8.7 8.5 12.5

Benzene (volume %) 1.60 0.1-5.18 1.60 1.60 0.64

Sulfur (ppm) 338 10-1170 305 313 269

MTBE d 

## (volume %) -- 0.1-13.8 -- 15 11 g



## EtOH d 

## (volume %) -- 0.1-10.4 10 7.7 10 h 

## RVP c 

## (PSI)

a As defined in the Clean Air Act.

b 1990 Motor Vehicle Manufacturer’s Association (MVMA) survey.

c Winter (W) Reid Vapor Pressure (RVP) higher than Summer (S) to maintain vehicle performance.

d Oxygenate concentrations shown are for separate batches of fuel; combinations of both methyl tertiary butyl ether

(MTBE) and ethanol (EtOH) in the same blend can never be above 15 volume percent total.

e Except as noted, values in this column are volume-weigh ted average based on preliminary analysis of a portion of

1996 RFG batch reporting data submitted to EPA by refineries and importers. Numbers are subject to change.

f The lower RVP number is average for RFG designated fo r sale in VOC Control Region 1; the higher RVP number

for VOC Control Region 2. In general, Region 1 areas are to the south and/or west.

g This is a “typical” value for an RFG batch containing MTBE as the sole oxygenate; this provides about 2%

oxygen by weight.

h This is a “typical” value for an RFG batch containing ethanol. Ethanol is not combined with other oxygenates in

VOCcontrolled RFG. There are economic incentives for blending ethanol at this level, which provides about 3.5%

oxygen by weight

i. T(50) and T(90) refers to temperatures at which 50% and 90%, respectively, of gasoline volume is distilled.



# 2-5

# Table 2-2. Summary of sample collections in urban MEs

ME # ME Description Replicates Biomarker 5 min

Canister Sampling Time

(min)

1 In-Cabin Congested Freeway 5 40

2 In-Cabin Urban Canyon 3 40

3 In-Cabin Refueling 5 20

4 In-Cabin Underground Garage 5 40

5 In-Cabin Toll Plaza 3 40

6* Roadway Tunnel 5 40

7 Outdoor Refueling 5 yes yes 20

8 Sidewalk 3 40

8/9 Sidewalk/Bus Stop 3 40

10 Outdoor Surface Parking 3 40

11 Outdoor Underground Garage 5 yes yes 40

12 Outdoor Toll Plaza 3 40

13* In-cabin Trailing High-Emitting Vehicles 5 yes yes 40

*ME13 was substituted for ME6 in Atlanta and Chicago.



# 2-6

# Table 2-3. Mass ratios of MTBE to benzene in Houston by ME.

2-7 Microenvironment ME Summer Winter

Freeway 1 1.72 ± 0.49 2.88 ± 1.33

Urban Canyon 2 1.10 ± 0.41 2.56 ± 0.80

In-Cabin Refueling 3 24.91 ± 12.19 41.96 ± 21.35

In-Cabin Underground Garage 4 3.22 ± 1.49 2.35 ± 1.78

In-Cabin Toll Plaza 5 2.49 ± 0.77 2.99 ± 1.14

Tunnel 6 2.74 ± 0.42 5.33 ± 6.63

Outdoor Refueling 7 28.82 ± 12.01 55.77 ± 26.83

Sidew 19 1.15 ± 0.06

Bus 13 1.31 ± 0.18

Su 6.93 ± 6.57

Out 37 3.30 ± 1.50

Out 81 2.78 ± 1.18 alk 8 2.34 ± 0.

Stop 9 2.87 ± 1.

rface Parking 10 1.94 ± 0.36

door Underground Garage 11 2.60 ± 0.

door Toll Plaza 12 2.48 ± 1.2-8Table 2-4. Mass ratios of MTBE tobenzene in vehicle exhaust, gasoline vapor and liquid gasoline.Test SetFuelYear Average StdevReferenceRatios in LDGV ExhaustCRPAQS/GDS dyno exhaustLos Angeles20010.62 1.35Fitz et al. 2003CRPAQS/GDS dyno warm-startsLos Angeles20010.43 1.43Fitz et al. 2003CRPAQS/GDS dyno hi-emLos Angeles20011.11 3.17Fitz et al. 2003SWRI FTP - summerHouston20040.44 0.24Merritt, 2005SWRI FTP - winterHouston20051.40 0.55Merritt, 2005SWRI FTP- normalHouston 2004 and 2005 0.60 0.45Merritt, 2005SWRI FTP- malfunctionHouston 2004 and 2005 1.24 0.71Merritt, 2005Ratios in Tunnel and Roadway SamplesWEO3 on-roadLos Angeles20002.96 1.03 Fujita et al.2003a; Fujita et al., 2003bLA tunnels-corrected for running lossLos Angeles 1995 and 1996 0.32 0.99Fujita et al., 2003bLA tunnels, uncorrectedLos Angeles 1995 and 1996 1.69 0.54Fujita et al., 2003bAPI houston tunnel (ME6)Houston 2004 and 2005 3.36 1.35This studyRatio in Gasoline VaporLA vaporLos Angeles199516.63Fujita et al., 2003bWEO3 vaporLos Angeles200044.98Fujita et al.2003a; Fujita et al., 2003bSWRI shed - malfunctionHouston 2004 and 2005 20.52 29.20Merritt, 2005SWRI shed - malfunction, outlier removed Houston 2004 and 2005 5.93 1.60Merritt, 2005estimated from fuel content - summerHouston200432.8Merritt, 2005estimated from fuel content - winterHouston200543.9Merritt, 2005Ratios in Liquid GasolineLA gasoline - 1995 RFGLos Angeles199511.79Fujita et al., 2003bWEO3 gasolineLos Angeles200019.56 5.23 Fujita et al.2003a; Fujita et al., 2003bgds gasolineLos Angeles200117.15 5.49Gabele, 2003API gasoline - summerHouston200413.28Merritt, 2005API gasoline - winterHouston200417.87Merritt, 2005

# Table 2-5. Fractional contributions of evaporative emissions to total motor vehicles emissions in

Houston by ME.

Microenvironment ME Summer Winter

Freeway 1 0.04 ± 0.02 0.03 ± 0.03

Urban Canyon 2 0.02 ± 0.01 0.03 ± 0.02

In-Cabin Refueling 3 0.76 ± 0.38 0.95 ± 0.50

In-Cabin Underground Garage 4 0.09 ± 0.05 0.02 ± 0.04

In-Cabin Toll Plaza 5 0.06 ± 0.02 0.04 ± 0.03

Tunnel 6 0.07 ± 0.01 0.09 ± 0.16

Outdoor Refueling 7 0.88 ± 0.37 1.28 ± 0.63

Sidewalk 8 0.06 ± 0.01 -0.01 ± 0.00

Bus Stop 9 0.08 ± 0.04 0.00 ± 0.00

Surface Parking 10 0.05 ± 0.01 0.13 ± 0.15

Outdoor Underground Garage 11 0.07 ± 0.01 0.04 ± 0.04

Outdoor Toll Plaza 12 0.06 ± 0.06 0.03 ± 0.03



# Evaporative Emissions Contribution

0.0 0.5 1.0 1.5 2.0

1 2 3 4 5 6 7 8 9 10 11 12



# MEFraction 

# summer

winter

Figure 2-1.Fractional contributions of evaporative emissions to total motor vehicles emissions in

Houston by ME.

2-9

# 2.5 References

Fujita, E.M., Z. Lu, L. Sheetz, G. Harshfield, T. Hayes, and B. Zielinska (1997c). Hydrocarbon

Source Apportionment in Western Washingt on. Report prepared for the State of

Washington Department of Ec ology, Lacy, WA, September, 1997.

Fujita, E.M., R.E. Keislar, J.L. Bowen, W. Goliff, F. Zhang, L.H. Sheetz, M.D. Keith, J.C.

Sagebiel, and B. Zielinska (1999a). 1998 Central Texas On-Road Hydrocarbon Study.

Final report prepared for the Texas Depart ment of Transportation, Austin, TX under

subcontract to PBS&J, Austin, TX, March, 1999.

Fujita E.M. (2001). Hydrocarbon Source Apportio nment for the 1996 Paso del Norte Ozone

Study. Science of the Total Environment, 276 :171-184.

Fujita, E.M., D.E. Campbell, B. Zielinska, J. C. Sagebiel, J.L. Bowen, W. Goliff, W.R.

Stockwell, and D.R. Lawson (2003a). Diur nal and Weekday Variations in Source

Contributions of Ozone Precursors in California’s South Coast Air Basin. J. Air & Waste

Manage. Assoc. 53 :844-863.

Fujita, E.M. and D. Campbell (2003b). Valida tion and Application Protocol for Source

Apportionment of Photochemical Assessmen t Monitoring Stations (PAMS) Ambient

Volatile Organic Compound (VOC) Data. Final report prepared for the U.S.

Environmental Protection Agency under EPA Star Grant #GR826237-01-0, August 31,

2003.

Gabele, P. Support of the Gasoline/Diesel Part iculate Matter Split Study. Final report submitted

by U.S. Environmental Protection Agency to Department of Energy through Interagency

Agreement (IAG) No. DE-A I04-2001AL67138, March 17, 2003.

Kirchstetter, T.W., B.C. Singer, R.A. Harley, G.R. Kendall, and J.M. Hesson (1999). Impact of

California Reformulated Gasoline on Moto r Vehicle Emissions: 2. Volatile Organic

Compound Speciation and Reactivity. Environ. Sci. Technol., 33 :329-336.

Pierson, W., E. Schorran, E. Fujita, J. Sagebiel, D. Lawson, and R. Tanner (1999). Assessment

of Non-Tailpipe Hydrocarbon Emissions from Motor Vehicles. J. Air Waste Manage.

Assoc., 49: 498-519.

Reid, R.C., J.M. Prausnitz and B.E. Poling (1987). Composition of Vapor Emitted from a

Vehicle Gasoline Tank During Refueling. SAE Technical Paper Series, paper no.

860086.

Zielinska, B. E.M. Fujita, and J.C. Sagebiel, D. Campbell, L.R. Smith and T. Johnson (2003).

Exposure Protocol and Study Plan for the Section 211 (B) Tier 2 High End Exposure

Screening Study of Baseline and Oxygenated Gasoline. Prepared for American Petroleum

Institute, 1220 L. Street, Washington , DC 20005-4007. Final Version. October 1, 2003.

2-10

# 3. Determination of the Quantitative Relationships between Levels of

Volatile Air Toxics and Carbon Monoxide Measured In High End

Microenvironments and At Nearby Air Quality Monitoring Stations

3.1 Introduction

The U.S. Environmental Protection Agency conducts national-scale assessments of air

toxics in order to set program priorities, charact erize risks, and track progress towards achieving

the goals of the national air toxics progr am as established by the 1990 Clean Air Act

Amendments (CAAA). As part of the National Air Toxics Assessment (NATA), EPA conducted

a national screening-level assessment for 1996 and 1999 to characterize the potential risks

associated with inhalation exposures to 33 air toxi cs and diesel particulates. The screening-level

assessment estimated outdoor air toxics conc entrations across the US and related these

concentrations to population exposures.

The Assessment System for Population E xposure Nationwide (ASPEN) model was used

by EPA to estimate outdoor air toxics concentr ations across for every census tract in the

continental United States, Puerto Rico and the Virg in Islands. To enable the simulation of a large

number of air toxics nationwide, a number of simplified approaches are incorporated into the

model. The model uses a simplified approach to simulate atmospheric chemistry such as reactive

decay and secondary formation (production of an air toxics compound due to chemical reactions

in the atmosphere). A uniform background concentr ation is added for some pollutants for which

information is available to compensate because the model simulates only pollutant transport

within 50 kilometers of any individual source. For those air toxics with high levels of

background concentrations, the mode l’s ability to predict ambien t concentrations are greatly

impacted by the accuracy of background estimates. Past comparisons with limited monitoring

data show that the modeled air toxics concen trations are generally within two orders of

magnitude of measured concentrations.

For the exposure-modeling portion of the analysis, EPA used the Hazardous Air Pollutant

Exposure Model (HAPEM). The HAPEM modeli ng approach simulates the movements of

various population groups thr ough zones of varying air quality. Each zone is defined by a

geographic location (typically a census tract) and a microenvironment (ME). The patterns of

movements among the zones are determined by diary-derived activity data and commuting data

acquired from the U.S. census. Ambient concen trations are estimated by the ASPEN dispersion

model based on local emissions and meteorological data. The po llutant concentration in a

specific ME is estimated as a function of th e ambient concentration by a linear expression

containing three terms that vary with ME: the pene tration factor (the ind oor/outdoor ratio in the

absence of indoor sources), the additive factor (accounts for contribution of indoor sources), and

the proximity factor (accounts fo r distance to specific outdoor sources such as roadways).

Estimates for these factors for 33 HAPS have been obtained from various fi eld studies and from

previous modeling exercises. In general, there is a high degree of uncertainty associated with

HAPEM exposure estimates because of the limited data available for estimating the ME factors

(Rosenbaum, 2005).

3-1

# The DRI conducted measurements quantifying exposures to automotive emissions in

microenvironments (MEs) representing the upper-end (> 99 th 

# percentile) of th e distribution of

inhalation exposures to evaporative and exha ust emissions of conventional and oxygenatedgasoline. The study was conducted as part of the Section 211(b) Tier 2 High-End Exposure

Screening Study of Baseline and Oxygenated Gasoline. DRI and SwRI conducted measurements

under controlled conditio ns to establish quantitative rela tionships between tailpipe and

evaporative emission rates to exposure levels in a vehicle cabin and attached residential garage.

Field exposures also were measured in several high-end exposure MEs in Atlanta, Chicago, and

Houston during winter and summer. Target species (TVOC, CO, BT EX, HCHO,1,3-BD, MTBE,

EtOH) were measured within MEs, breathing z ones, and breath. This section examines the

quantitative relationships between CO exposure levels in these MEs to the corresponding fixed

site measurements at nearby air monitoring stations. These comparisons are extended for

Houston to volatile organic mobile source air to xics, which was the only city among the three

with available data. These relationships are compared to the HAPEM proximity factors (Long

and Johnson, 2004) that were used in the National Air Toxics Assessments.

3.2 Experimental

DRI measured seasonal in-cabin breathing z one exposures for urban roadways and other

high-end MEs in Houston (6/3-7/9/04; 2/1-2/8/05), Chicago (8/5-8/20/03; 3/3-3/17/04), and

Atlanta (7/28-8/8/02; 8/23-9/3/03 ; 2/10-2/29/04) using a combinat ion of time-integrated samples

and continuous instruments for thirteen diffe rent MEs listed in Tabl e 3-1. Three replicate

exposure measurements were made for low va riability MEs and five for MEs with higher

variability (i.e., ME13-trailing high emitting ve hicles, ME11-underground garages, and ME7-

outdoor refueling). Measurements in each ME were taken over a period of 20-40 minutes

beginning at the top of the hour. Shorter samplin g times were used for refueling events and

parking garage exits after sporting events.

The integrated samples included whole-air canister samples for CO, BTEX, MTBE, and

1,3-BD, acidified 2,4-diphenylhydrazine (DNPH) cartridges for HCHO and CH 3 

# CHO, and a

multi-bed (TenaxTA-Carbotrap-Carbosieve) so lid adsorbent tube for EtOH. Continuous

measurements included both non-dispersive in frared (NDIR) and passive electrochemical

(Langan T-15) devices for CO and an active photo -ionization detector (PID) for TVOC with an

ionization potential below 10.6 eV (principally olefins and ar omatic species). Sampling and

analytical methods are described in Section 1 and in the study pl an (Zielinska et al., 2003).

Ambient CO and VOC data were retrieved from EPA’s Air Quality System (AQS) for the

specific periods of the field st udy in each city and compared to the ME measurements. The

ambient monitoring and ME locations are mapped for each city in Figures 3-1a to 3-1c although

some ME locations are overlapped by adjacen t MEs. AQS VOC data were not available for

Atlanta; incomplete data were available for a single site (Northbrook, IL) in Chicago located 20

miles N/NW of city center that is unlikely re presentative of urban Chicago. Speciated hourly

GC/FID VOC data were availabl e from two sites in Houston for both summer and winter. All

sites reporting CO and VOC data within each metropolitan area were averaged together for the

purposes of comparison. The average CO and ben zene concentrations did not show substantial

spatial variation w ithin each city.

3-2

# 3.3 Results and Discussion

Exposure levels are directly related to source emission rate s in the ME and inversely

related to source distance and the extent of dilution, itself a function of meteorology and any

physical obstructions that inhibit dilution. Hourly values from air quality m onitoring stations in

urban areas typically represent neighborhood scale exposure levels while 20-40 minute measures

from MEs listed in Table 3-1 are intended to repr esent the high end exposures exceeding the 99th

percentile. Consequently, the tabu lated ME ratios reflect exposure s scripted to reflect ‘worstcase’ conditions rather than popul ation-average ME factors for th ese locations. Such information

should be used solely to evaluate extreme expos ures and not misinterpr eted as ‘typical’ ME

exposures encountered by the general population.

Quantitative relationships for CO between ME measures and fixed site measurements at

nearby air monitoring stations are examined fi rst. CO is non-reactive and commonly measured

year-round as a primary mobile source emission th at is generally correla ted with BTEX and 1,3-

BD. Table 3-2 shows the averages and standard de viations of the ratios of time-integrated CO

from canister samples to the corresponding hourly CO from the ambient air monitoring stations

in Houston, Atlanta, and Chica go by season and ME. As expected, the ratios are higher in MEs

that are nearer to operating vehicle engines, especially in underground garages where dispersion

of pollutants is limited. The average ratios for in -cabin exposures in congested freeway traffic

ranged from 2 to 9 with lower ratios in the wint er. Ratios were highest in Atlanta and lowest in

Chicago. The seasonal and city-specific differen ces hold for most of the other MEs. Notable

exceptions to the seasonal differences are the underground garages where th e ratios are higher in

the winter in all three cities, most likely due to the higher cold-start em issions. Garage size,

ventilation, and spatial-temporal vehicle activity patterns account for the variance differences

between underground garages. The garage in Atlanta is smaller, less ventilated, and more used

than the garages in Houston or Chicago. While CO is a good exhaust sp ecies tracer, correlation

with evaporative emissions is less. ME/ambient ra tios are generally lower for CO than most of

the other pollutants. This is most likely due to higher urban background levels of CO.

Table 3-3 shows average Houston BTEX and 1, 3-BD ME/ambient ratios (± SD), i.e., the

time-integrated canister value to the corresponding hourly monitori ng station GC/FID value. In

contrast to CO, BTEX ME/ambient ratios are su bstantially higher for refueling (ME 3, ME 7).

The BTEX ratios are closer to corresponding ratios derived fo r CO during winter but higher

during summer. Since 1,3-BD is an exhaust species , the relative variation of ME/ambient ratios

is similar to CO. 1,3-BD measures in MEs with high MTBE were invalid due to interferences

(see Section 1).

The integrated exposure measurements are 20-40 minute averages. Continuous CO and

VOC PID measurements show hi gher peak (1-5 minutes) exposures. Continuous instruments

provide sensitive proportionate measures of short-te rm target species variability since continuous

time-averaged traces are well correlated to the corresponding time-inte grated measurements.

Consequently, the normalized continuous CO or VOC PID measures were used to reconstruct 1-

minute time-series concentrations for specific components. Either CO or VOC PID traces are

suitable surrogates in exhaust- dominated MEs; VOC PID values are suitable surrogates in

evaporative emissions-dominated MEs such as refueling. Reconstructed time-series and ranges

3-3

# of estimated 1-minute values are summarized in Section 1. Figures 3-2a through 3-2c show 20-

40 minute average and maximal estimated 1-mi nute values for benzene, 1,3-BD, and HCHO,

respectively. Short-term exposures from eva porative-dominated ME3 and ME7 range more

widely than those from other exhaust-dominated MEs.

3.4 Conclusions

MEs in close proximity to running vehicle engi nes have enhanced CO relative to ambient

levels with enrichment ratios approaching 40 where ventilation is limited, as in underground

garages. Average in-cabin CO/amb ient ratios in congested freeway traffic range from 2-9 with

lower winter ratios. ME locations less proximate to operating vehicles, such as gas stations and

urban sidewalks, have CO/ambient ratios of 0.5-2.

The Houston benzene ME1/ambient ratio of 9.8 ± 3.8 for exceed the HAPEM5 median

proximity factor of 4.9 (tria ngular distribution mode:range 1.9:0-14.3) and HAPEM4 proximity

factor of 6.9 for this ME (Rosenbaum, 2005; Long and Johnson, 2004), although by less than

expected. The HAPEM4 factors may be elevat ed compared to present conditions since

measurements occurred before 1991 when benzene fuel levels and roadway fleet emissions were

higher than today. HAPEM5 proximity factors may al so need to be adjusted since they were

based on a 1998 scoping study where measurements ‘highlighted trailing behind heavy duty

diesel vehicles and diesel c ity buses when possible’. Houston ME/ambient ratio comparisons

also generally exceed the other HAPEM factors li sted in Table 3-4. Refueling ratios (ME3, ME7)

for benzene were substantially higher than the corresponding HAP EM factors also as expected.

Concentrations of exhaust compounds such as CO and 1,3-BD were enhanced under reduced

ventilation situations.

3.5 References

Rosenbaum, A. (2005). The HAPEM5 User’s Guide. Report prepared by ICF Consulting for the

U.S. Environmental Protection Agency, Research Triangle Park, NC, March 2005.

Long, T. and T. Johnson (2004). Development of Penetration and Proximity Microenvironment

Factor Distributions for the HAPEM5 in S upport of the 1999 National-Scale Air Toxics

Assessment (NATA). Memorandum prepared by TRJ Environmental, Inc. for the U.S.

Environmental Protection Agency, Research Triangle Park, NC, April 5, 2004.

Zielinska, B. E.M. Fujita, and J.C. Sagebiel, D. Campbell, L.R. Smith and T. Johnson (2003).

Exposure Protocol and Study Plan for the Section 211 (B) Tier 2 High End Exposure

Screening Study of Baseline and Oxygenated Gasoline. Prepared for American Petroleum

Institute, 1220 L. Street, Washington , DC 20005-4007. Final Version. October 1, 2003.

3-4

# Table 3-1. Summary of sample collec tions in urban microenvironments

3-5 ME # ME Description Replicates Biomarker 5 min

Canister Sampling Time

(min)

1 In-Cabin Congested Freeway 5 40

2 In-Cabin Urban Canyon 3 40

3 In-Cabin Refueling 5 20

4 In-Cabin Underground Garage 5 40

5 In-Cabin Toll Plaza 3 40

6* Roadway Tunnel 5 40

7 Outdoor Refueling 5 yes yes 20

8 Sidewalk 3 40

8/9 Sidewalk/Bus Stop 3 40

3 40

5 yes yes 40

3 40

1 5 yes yes 40

*M 10 Outdoor Surface Parking

11 Outdoor Underground Garage

12 Outdoor Toll Plaza

3* In-cabin Trailing High-Emitting Vehicles

E13 was substituted for ME6 in Atlanta and Chicago.Table 3-2. Average and standard deviationin ratios of the time-integrated CO from canister samples to the corresponding hourlyCOfrom regional ambient air monitoring sites for Houston,Atlanta and Chicago by season and microenvironment.SummerWinterMicroenvironmentHouston Atlanta Chicago Houston Atlanta Chicago1 Congested Freeway, In-Cabin 4.6 ± 1.0 9.1 ± 6.5 2.6 ± 0.4 4.0 ± 1.0 5.4 ± 1.9 1.7 ± 0.42 Urban Canyon, In-Cabin5.2 ± 2.5 3.9 ± 3.9 2.9 ± 1.4 12.1 ± 10.9 2.7 ± 5.6 1.0 ± 0.53 Refueling, In-Cabin3.6 ± 0.9 1.4 ± 2.7 0.7 ± 0.3 4.1 ± 3.2 1.3 ± 0.6 0.5 ± 0.14 Underground Garage, In-Cabin 8.4 ± 8.0 16.9 ±0.8 7.9 ± 3.4 21.4 ± 12.5 38.8 ± 0.2 12.6 ± 5.85 Toll Plaza, In-Cabin4.1 ± 1.0 6.4 ± 0.0 1.6 ± 0.5 3.6 ± 0.6 2.7 ± 0.0 1.0 ± 0.16 Tunnel, In-Cabin8.4 ± 1.76.3 ± 1.5 9.7 ± 5.22.5 ± 0.47 Refueling, Outdoor1.9 ± 0.8 1.2 ± 1.8 0.9 ± 0.3 3.3 ± 2.5 2.1 ± 1.4 0.8 ± 0.98 Sidewalk1.9 ± 0.5 1.9 ± 0.5 1.1 ± 0.2 1.3 ± 0.6 1.9 ± 0.9 0.9 ± 0.09 Sidewalk/BusStop1.5 ± 0.3 2.4 ± 0.3 1.6 ± 0.6 1.8 ± 0.1 1.9 ± 0.2 1.1 ± 0.210 Surf Parking, Outdoor3.3 ± 1.2 5.3 ± 0.7 2.1 ± 1.3 4.7 ± 2.9 3.3 ± 0.6 1.4 ± 0.511 Underground Garage, Outdoor 8.6 ± 7.4 26.8 ±3.6 3.9 ± 2.3 17.1 ± 11.2 32.9 ± 2.0 12.4 ± 7.212 Toll Plaza, Outdoor7.6 ± 2.7 6.5 ± 8.8 3.2 ± 0.2 6.2 ± 4.3 7.4 ± 16.5 1.8 ± 0.313 Following High Emitter, In-Cabin8.4 ± 2.612.0 ± 4.23-6Table 3-3. Average and standard deviationsin ratios of BTEX and 1,3-BDfrom time-integrated canister samples to the correspondinghourly automated GC data from the ambient air monitoringsites in Houston.MicroenvironmentBenzeneToluene Etbenzene m&p-Xylene o-Xylene 1,3-ButadieneSummer1 Congested Freeway, In-Cabin9.8 ± 3.87.8 ± 1.95.4 ± 1.85.2 ± 0.66.6 ± 1.58.1 ± 3.62 Urban Canyon, In-Cabin7.4 ± 3.06.8 ± 1.15.6 ± 3.35.6 ± 1.45.8 ± 2.47.3 ± 1.23 Refueling, In-Cabin565 ± 791 446 ± 666 140 ± 188 115 ± 136 117 ± 1474 Underground Garage, In-Cabin 19.4 ± 13.9 17.2 ± 15.0 16.0 ± 13.7 14.2 ± 12.8 17.1 ± 17.0 50.0 ± 66.45 Toll Plaza, In-Cabin9.1 ± 4.47.8 ± 3.66.8 ± 4.96.2 ± 3.47.1 ± 3.87.8 ± 5.26 Tunnel, In-Cabin25.9 ± 14.1 12.4 ± 6.8 7.8 ± 2.97.5 ± 2.78.9 ± 2.7 37.9 ± 20.07 Refueling, Outdoor1312 ± 1811 974 ± 1356 335 ± 479 219 ± 227 197 ± 1988 Sidewalk15.4 ± 10.6 10.6 ± 4.4 12.5 ± 15.3 11.9 ± 14.0 14.2 ± 17.1 5.8 ± 2.49 Sidewalk/BusStop4.7 ± 2.02.9 ± 1.31.8 ± 0.41.9 ± 0.52.3 ± 0.62.0 ± 1.310 Surf Parking, Outdoor11.5 ± 5.5 8.3 ± 2.87.4 ± 2.16.7 ± 3.17.0 ± 3.25.5 ± 1.911 Underground Garage, Outdoor16.7 ± 5.3 15.7 ±7.2 13.8 ± 7.2 11.1 ± 7.2 14.4 ± 9.6 39.6 ± 29.512 Toll Plaza, Outdoor14.7 ± 8.5 11.3 ± 10.2 9.2 ± 8.38.5 ± 7.6 11.0 ± 10.6 13.4 ± 13.1Winter1 Congested Freeway, In-Cabin4.6 ± 1.66.4 ± 3.76.4 ± 3.08.8 ± 5.29.7 ± 5.1 0.36 ± 0.062 Urban Canyon, In-Cabin17.0 ± 21.7 22.7 ± 27.7 22.1 ± 26.4 31.1 ± 36.9 26.7 ± 28.93 Refueling, In-Cabin35.0 ± 25.4 36.5 ± 27.2 22.7 ± 18.2 25.3 ± 19.2 24.2 ± 16.34 Underground Garage, In-Cabin 37.2 ± 15.8 32.3 ± 12.9 24.0 ± 9.4 23.2 ± 8.5 25.0 ± 9.75 Toll Plaza, In-Cabin3.5 ± 1.73.7 ± 1.54.3 ± 1.74.6 ± 2.05.3 ± 2.16 Tunnel, In-Cabin8.5 ± 6.79.0 ± 6.97.0 ± 4.58.9 ± 6.49.9 ± 7.2 1.91 ± 0.547 Refueling, Outdoor160 ± 148 119 ± 92 49.1 ± 39.2 56.1 ± 54.3 44.6 ± 33.78 Sidewalk2.8 ± 0.82.6 ± 1.02.7 ± 0.73.6 ± 1.73.7 ± 1.3 0.09 ± 0.109 Sidewalk/BusStop3.3 ± 0.33.6 ± 0.33.5 ± 1.14.2 ± 0.74.3 ± 0.810 Surf Parking, Outdoor4.3 ± 3.07.5 ± 6.45.7 ± 2.96.1 ± 2.16.0 ± 2.511 Underground Garage, Outdoor 28.3 ± 16.5 25.0 ±13.0 20.8 ± 11.3 21.9 ± 11.1 22.9 ± 10.7 0.60 ± 0.0312 Toll Plaza, Outdoor4.8 ± 0.74.5 ± 1.44.5 ± 1.84.9 ± 1.65.4 ± 1.93-7Table 3-4. Houston benzene ME/ambient ratiocomparison with HAPEM benzene ME factorsMESummerWinterHAPEM4PROXHAPEM5 PROXDistribution (mode;median)HAPEM5 PROXRange0-14.41 Congested Freeway, In-Cabin9.84.65.2, 6.9*Triangular 1.9; 4.90-14.42 Urban Canyon, In-Cabin7.4174.4Triangular 1.9; 4.90-7.13 Refueling, In-Cabin565354.4Triangular 1.6; 2.70-7.14 Underground Garage, In-Cabin19371.0Triangular 1.6; 2.70-14.45 Toll Plaza, In-Cabin9.13.54.4Triangular 1.9; 4.90-14.46 Tunnel, In-Cabin268.54.4Triangular 1.9; 4.90-7.17 Refueling, Outdoors13001604.4Triangular 1.6; 2.70-7.18 Sidewalk152.84.4Triangular 1.6; 2.70-7.19 Sidewalk, BusStop4.73.34.4Triangular 1.6; 2.70-7.110 Surface Parking, Outdoors124.34.4Triangular 1.6; 2.70-7.111 Underground Garage, Outdoors17281.0Triangular 1.6; 2.70-7.112 Toll Plaza, Outdoors154.84.4Triangular 1.6; 2.7* truck, car3-8Figure 3.1a. Location of ME sampling and fixed monitoring stations in Chicago Metro Area.3-9Figure 3.1b. Location of ME sampling and fixed monitoring stations in Houston Metro Area.3-103-11Figure 3.1c. Location of ME sampling and fixed monitoring stations in Atlanta Metro Area.

### Benzene - Estimated Average 1-minute Concentrations

0 20 40 60 80 100 120 14001020304050708091011121301020304050708091011121301020304050607080910111213010203040506070809101112010203040506070809101112010203040506070809101112

Summer Winter Summer Winter Summer Winter

Atlanta Chicago HoustonConc (ppbv)



### Benzene - Estimated Maximum 1-minute Concentrations

0 500 1000 1500 2000 250001020304050708091011121301020304050708091011121301020304050607080910111213010203040506070809101112010203040506070809101112010203040506070809101112

Summer Winter Summer Winter Summer Winter

Atlanta Chicago HoustonConc (ppbv)



# Figure 3-2a. Comparison of average versus the maximum 1-minute benzene levels by

city, season and microenvironment.

3-12

### 1,3-Butadiene - Estimated Average 1-minute Concentrations

0 1 2 3 4 501020304050708091011121301020304050708091011121301020304050607080910111213010203040506070809101112010203040506070809101112010203040506070809101112

Summer Winter Summer Winter Summer Winter

Atlanta Chicago HoustonConc (ppbv)



### 1,3-Butadiene - Estimated Maximum 1-minute Concentrations

0 5 10 15 20 2501020304050708091011121301020304050708091011121301020304050607080910111213010203040506070809101112010203040506070809101112010203040506070809101112

Summer Winter Summer Winter Summer Winter

Atlanta Chicago HoustonConc (ppbv)



# Figure 3-2b. Comparison of average versus the maximum 1-minute 1,3-butadiene levels

by city, season and microenvironment.

3-13

### Formaldehyde - Estimated Average 1-minute Concentrations

0 10 20 30 4001020304050708091011121301020304050708091011121301020304050607080910111213010203040506070809101112010203040506070809101112010203040506070809101112

Summer Winter Summer Winter Summer Winter

Atlanta Chicago HoustonConc (ppbv)



### Formaldehyde - Estimated Maximum 1-minute Concentrations

0 20 40 60 80 100 120 140 16001020304050708091011121301020304050708091011121301020304050607080910111213010203040506070809101112010203040506070809101112010203040506070809101112

Summer Winter Summer Winter Summer Winter

Atlanta Chicago HoustonConc (ppbv)



# Figure 3-2c. Comparison of average versus the maximum 1-minute formaldehyde levels

by city, season and microenvironment.

3-14

# 4. Relationships of Attached Garage and Home Exposures to Fuel

Type and Emission Levels of Garage Sources

4.1 Introduction

This chapter describes experiments to determine relationships between measured

fuel and exhaust components in the attach ed garage, adjacent room (kitchen), and

garaged vehicle emission levels. The same ve hicles, fuels and vehicle malfunctions used

here are used in Chapter 5 to explore the effects of ventilation, proximity, and leading

vehicle emission levels on trailing vehicle in-cabin exposures. These measurements are

also described in the executive summary and Chapter 1.

Measurements were performed during June-July 2002 and February-March 2005

in San Antonio, TX on a sedan and a pickup truck using either non-oxygenated

conventional gasoline, gasohol (E10), or an MTBE-oxygenated gasoline. The vehicles

were tested in both a normal emissions mode and a malfunctioning high emitter mode

where emissions were adjusted to ex ceed 2 grams of non-methane hydrocarbons

(NMHC) per mile as measured by the Federal Test Procedure (FTP).

4.2 Experimental

Methods and procedures specific to th e attached garage experiments are

summarized below. Sampling and analyses methods are described in Chapter 1 and

Appendix B.

4.2.1 Vehicles and Vehicle Test Methods

The Southwest Research Institute (SwR I) procured two test vehicles and

determined their evaporative/tailpipe emi ssions in the normal/malfunction modes using

the three test fuels. The test vehicles, a seda n and full-sized V8 truck, were chosen within

the 1993-1996 model years from vehicles with 90,000-110,000 odometer miles. The

chosen 1993 Toyota Camry (2.2L 4-cylinder engine) and 1995 Ford F150 Pickup truck

(5.0L V8 engine) were operated in normal, as purchased, modes and in “high emitter”

modes with the catalytic conve rter removed and emission levels above 2 grams per mile

NMHC as measured on the FTP driving cycle. While converter removal sufficed for the

F150 truck, a calibrated manifold leak was also needed to achieve the ≥ 2g/mile Camry

emissions. SwRI determined dynamometer FTP emissions for each vehicle with all three

fuels in the two emission modes (24 tests). Emission control components could be

reproducibly adjusted to re present normal and reasonabl e high-end approximations ( ≥

2g/mile) of real world exhaust emissions. The vehicle properties are summarized in Table

4.2-1 and included in the Sw RI report (Appendix F).

4-1

# Table 4.2-1. Summary of vehicles used.

Vehicle Make Model Year Engine Malfunction

Truck Ford F150 1995 5.0 L V8 Removed Catalyst.

Sedan Toyota Camry 1993 2.2 L 4

cylinder Removed Catalyst and added

leak to manifold.

Regulated exhaust emissions (THC, NMHC, CO, NOx), fuel economy, and

specific VOCs (MTBE, EtOH, BTEX, 1,3- BD, HCHO) were determined in

dynamometer FTP tests. During hot-soak SH ED tests, THC and specific VOCs (minus

HCHO) were also determined.

The FTP exhaust emission test uses the 1372 second Urban Dynamometer

Driving Schedule (UDDS) that is divided into cold/start transient 505 (Bag 1) and cold

stabilized 867 (Bag 2) second segments. This portion of the FTP is followed by a 10-

minute soak and a hot/start transient 505 (Bag 3) test. The FTP evaporative emission test

includes one hour Diurnal Heat Build (DHB) and Hot Soak Loss (HSL) tests. THC/VOC

emissions are recorded during the HSL segment of the test. Prior to the FTP cold-start

exhaust test, the DHB is conducted by fueli ng the test vehicle to 40 percent of tank

capacity with fuel < 55°F, attaching a heat ing blanket outside th e fuel tank, placing a

thermocouple in the tank fuel, hooking it up to computer control, and beginning the test

as fuel reaches 60°F (increasing at 0.4°F per minute for the 60-minute test to a 84°F final

temperature).

In the HSL segment, conducted immediately following exhaust emission testing,

the vehicle is driven into an evaporative emi ssion enclosure and allowed to “soak” in the

enclosure for one hour. THC/VOC emissions ar e measured at the beginning and end of

the one-hour segment and hot soak evaporative emissions are calculated.

4.2.2 Fuel Testing

Test fuel samples were subject to standa rd tests for Reid Vapor Pressure (RVP),

distillation range, Specific Grav ity, Sulfur, Benzene, HC Category (saturates, olefins,

aromatics), Oxygenated species (MTBE/EtOH) , carbon weight percent, hydrogen weight

percent, oxygen weight percent, and octane number. These re sults are presented in Table

4.3-1.

4.2.3 Test House

Fuel component levels were measured in the garage and in a room (kitchen)

adjacent to an attached garage using the fuels and test vehicles in normal and high emitter

modes. Appendix I shows the layout of the hous e. The double garage contained an active

ceiling fan that minimized emissions stratific ation and hot spots within the garage. The

garage also contained a pl astic gasoline container a nd gasoline-powered lawnmower

filled with the test fuels. The exhaust fan ove r the kitchen’s stove was not used during the

4-2

# experiments. However, the central air conditioning was active during the summer tests.

Garage and kitchen monitoring was conducted according to the scenarios described in

Table 4.2-2. Window and door ope nings, of the garage vehicle door, the kitchen door

between the garage and kitchen, and kitche n window were scripted. Time-integrated

canister, DNPH and solid adsorbent (for EtOH) cartridges, and SPME samples were

collected for each test. EtOH was measured for Chicago fuel only. Continuous or semicontinuous measurements were also operated during the expo sure periods. Measurements

were taken over scripted 30-minute scenario intervals through collocated sampling inlets

at breathing height (1.5 m) a meter dist ant from nearby walls in the kitchen and

unventilated garage. Continuous PID TVOC and Langan CO instruments sampled from

the kitchen before (background) and during 2002 tests. For the winter 2005 samples, a

second PID TVOC and the NDIR CO instrume nt were used to monitor the garage

continuously. In the summer 2002 sample s, the continuous MS200 BTEX and A- Ω

HCHO monitors sampled cycli cally through collocated inlets in the garage and kitchen

every 10 minutes.

A half-filled two-gallon plastic gasoline storage container with vent opened was

placed adjacent to a fueled lawnmower, with gas tank half filled, against the center of the

rear garage wall common with the kitchen. The container and lawnmower filled with the

appropriate fuel were placed in the garage one day before the series of vehicle tests for

that fuel began and remained there over th e duration of the tests. Scenario conditions

were changed every 30 minutes over the 3-hour protocol as describe d in the Table 4.2-2.

Ambient garage temperatures were record ed each 30 minutes. Tests were conducted

daily (excluding weekends ) over a two week period.

Table 4.2-2. Protocol for attach ed garage experiments.

Condition Time

(min) Garage

Door Kitchen

Door Kitchen

Window Inlet

Location Continuous

Instruments SPME Integrated

Canisters/

Cartridges

10 garage yes

10 kitchen yes Background

No vehicle,

but lawn

mower & gas 10 closed closed closed

garage yes 2 2

10 kitchen yes

10 garage yes Hot soak

vehicle,

lawnmower,

& gas 10 closed opened 1

min

& closed closed

kitchen yes 2

10 garage yes

10 kitchen yes Cooling

vehicle,

lawnmower,

& gas 10 closed closed closed

garage yes 2

10 kitchen yes

10 garage yes Cold vehicle,

lawnmower,

& gas

10 closed closed open

kitchen yes 2 2



# 4-3

## Condition Time

(min) Garage

Door Kitchen

Door Kitchen

Window Inlet

Location Continuous

Instruments SPME Integrated

Canisters/

Cartridges

10 garage yes

10 kitchen yes Cold start,

idling,

lawnmower,

& gas 10 open opened 1

min

& closed closed

garage yes 2

10 kitchen yes

10 garage yes No vehicle,

but

lawnmower,

& gas 10 closed closed closed

kitchen yes 2



# The first scenario condition, background, a ssesses levels in the kitchen and garage

prior to the beginning of vehicle testing. In the garage, background will include emissions

from the gasoline container and lawn mower. The hot soak condition should most closely

reflect the hot soak SHED tests performe d by SwRI. In this condition, the exposure

scenario is that of a person coming home from shopping and conveying purchases

through the kitchen-garage door into the home, allowing so me enhanced air exchange

between the garage and the kitchen. The next condition, cooling vehi cle, reflects a period

where the trapped garage air remains in the kitchen. The cold vehicle condition is

performed with the kitchen wi ndow open to allow outside fresh air exchange within the

kitchen (keeping the garage door closed). The cold start condition simulates a person

warming up his car in an open garage prior to leaving; th e kitchen door is open for one

minute to account for the extra trips to and fr om the vehicle. The vehicle is started and

then idled for the entire 30 minutes. The fi nal condition, no vehicle, represents kitchen

exposures after the vehicle has left. One inte grated canister and cartridge samples were

collected over background test and another one over all fi ve phases of the garage

experiments, as shown in Table 4.2-2.

4.3 Results

4.3.1 Fuel Analyses

The results of the fuel analyses are pres ented in Table 4.3-1. Fewer tests were run

on the Summer 2002 fuels.

The results confirm that there was no oxyge nate in the Atlanta conventional fuel,

that MTBE was present in the Houston fuel, and that ethanol was present in the Chicago

fuel. Across seasons total aromatics were sim ilar in the oxygenated fuels but higher in the

conventional fuel. Benzene levels range from 0.5-1.2 % with the conventional summer

fuel highest. The Reid Vapor Pressure (RVP) is higher in the winter fuels to ensure cold

start reliability.

4-4

# Table 4.3-1. Summary of propertie s for the six test fuels.

O2 Total wt% = total oxygen weight %

MeOH = methanol; EtOH = ethanol

4.3.2 Vehicle Regulated and Hot Soak Emissions

The vehicle emission tests were conducte d as described in Section 4.2. The details

of these tests are described in the SwRI Re port, attached in Appendix F. Tables 4.3-2

through 4.3-5 show the measured regulated exha ust and hot soak emissions from the test

vehicles for summer and winter test fuels. The FTP results show that all emissions

increased and the high emitter target of ≥ 2 grams NMHC per mile was achieved.

4-5

# Table 4.3-2. Regulated and Hot Soak Emissions from the Ford F-150, Summer 2002.

Table 4.3-3. Regulated and Hot Soak Emi ssions from the Ford F-150, Winter 2005.

Table 4.3-4. Regulated and Hot Soak Emissi ons from the Toyota Camry, Summer 2002

Table 4.3-5. Regulated and Hot Soak Emissi ons from the Toyota Camry, Winter 2005

4-6

# 4.3.3 Garage and Kitchen Exhaust/Evaporative Fuel Component Levels

This section summarizes emission compone nt concentrations observed in the

kitchen and attached garage. As discussed in Chapter 1, measured 1,3-BD levels are

biased upwards in the presence of high MTBE concentrations. In addition, a single

garage sample (sedan with gasohol in normal mode) was invalidated. The sample

contained high anomalous levels of BTEX, BTEX/1,3-BD and BTEX/CO ratios were 25-

and 88-fold higher, respectively, in the normal mode than the high emitter tests,

suggesting an anomalous source of BTEX su ch as an unrecorded garage fuel spill.

BTEX and 1,3-butadiane data presented in Tables 4.3-6 to 4.3-12 are from the

canister samples and ethanol is from the sorben t cartridges, as descri bed in Chapter 1 and

Appendix B..

4.3.3.1 Background and Overall Concentrations

The background samples, taken before th e vehicle was brought into the garage,

are presented in Table 4.3-6 for both the aver age (top section, separated for summer and

winter) and ranges of the data . Note that the max-min ra nges denote the single highest

values for each species individually across te sts. Gaps indicate missing samples. Both

HCHO and EtOH show relatively higher levels in the kitchen. HCHO off-gases from

residential furnishings and construction mate rials. EtOH is emitted from people, foods,

cleaning & personal care products, domestic garbage, and alcoholic beverages.

Table 4.3-6. Summary of Backgr ound Concentrations in Kitchen and Garage. Units are

ppbv, except as noted.

Budi13 Benze Tolue Etbz Mp_xyl O_xyl MTBE CO,ppm Formal EtOH

Kitchen Backgrounds

Summer 0.08 1.70 6.50 0.67 2.30 1.05 0.42 0.35 49.83 1215.58

Winter 0.21 3.93 7.47 4.82 7.47 4.32 1.31 0.87 13.51

Garage Backgrounds

Summer 0.02 2.68 8.87 0.92 3.25 1.14 0.20 0.15 20.29

Winter 0.12 2.29 5.40 0.85 3.13 1.21 1.11 0.78 7.70

Kitchen, all

Min 0.02 0.73 3.33 0.37 1.25 0.50 0.00 0.15 5.50 53.

Max 1.33 11.76 15.49 38.21 32.27 24.64 6.16 5.29 106.63 2194.10

Garage, all

Min 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 3.85 0.

Max 0.90 11.47 25.72 3.19 11.33 4.27 3.78 7.01 35.63 1475.60 60

90



## Budi13 = 1,3BD; Benze = benzene; Tolue = toluene, Mp_xyl = m,p-xylene; o_xyl = o-xylene,

Formal = formaldehyde; EtOH = ethanol



# The ranges of all samples taken during the vehi cle-related scenario portions are presented

in Table 4.3-7. As expected, the lower concen trations stem from normal mode vehicles

and higher levels from the high emitter mode.

4-7

# Table 4.3-7. Summary of Test Concentration Ranges in Ki tchen and Garage. Units are

ppbv, except as noted.

Budi13 Benze Tolue Etbz Mp_xyl O_xyl MTBE CO,ppm Formal EtOH

Kitchen, all

Min 0.02 0.18 2.49 0.25 0.78 0.43 0.00 0.00 0.00 158.

Max 1.64 11.17 15.58 3.02 9.06 5.12 13.27 10.85 95.59 670.20

Garage, all

Min 0.03 1.33 2.48 0.39 1.25 0.51 0.00 0.20 0.00 5.

Max 36.35 65.44 93.67 18.23 50.72 19.36 185.63 39.16 174.20 27.70 80

80



## Budi13 = 1,3BD; Benze = benzene; Tolue = toluene, Mp_xyl = m,p-xylene; o_xyl = o-xylene,

Formal = formaldehyde; EtOH = ethanol



# 4.3.3.2 Seasonal Impacts

Seasonal max trends are inconsistent. Tabl e 4.3-8 shows that differences seen in

the kitchen are smaller than in the garage. The garage has higher exhaust 1.3-BD and

HCHO in the summer, but lower CO values than in the winter.

Table 4.3-8. Seasonal Impact on Observed Ma ximum Concentrations (Units are ppbv,

except as noted).

. Budi13 Benze Tolue Etbz Mp_xyl O_xyl MTBE CO,ppm Formal EtOH

Kitchen Max-S 1.42 7.77 14.64 1.84 6.44 2.98 10.49 1.62 95.59 670.20

Max-W 1.64 11.17 15.58 3.02 9.06 5.12 13.27 10.85 54.78

Garage Max-S 36.35 65.44 93.67 18.23 50.72 19.36 93.63 28.60 174.20 27.70

Max-W 8.47 24.68 34.61 6.05 22.78 8.04 185.63 39.16 54.78



## Budi13 = 1,3BD; Benze = benzene; Tolue = toluene, Mp_xyl = m,p-xylene; o_xyl = o-xylene,

Formal = formaldehyde; EtOH = ethanol



# Tables 4.3-9 and 4.3-10 provide max a nd average values for normal mode

vehicles only. The maximum values for the normal vehicles are generally lower with

winter mean values higher than summer.

Table 4.3-9. Seasonal Impact on Observed Ma ximum Concentrations (Units are ppbv,

except as noted), Normal Mode Vehicles Only.

Normal Onl y Budi13 Benze Tolue Etbz Mp_xyl O_xyl MTBE CO,ppm Formal EtOH

Kitchen Max-S 0.29 4.87 14.35 1.80 6.44 2.48 1.59 0.81 95.59 519.70

Max-W 1.55 11.17 14.80 2.76 8.50 3.44 13.27 3.07 31.31

Garage Max-S 4.76 21.02 48.73 6.99 19.92 7.73 8.95 3.86 58.53 27.70

Max-W 8.47 24.68 34.61 6.05 22.78 8.04 185.63 39.16 54.78



# Table 4.3-10. Seasonal Impact on Observed Average Concentrations (Units are ppbv,

except as noted), Normal Mode Vehicles Only.

4-8Normal Onl y Budi13 Benze Tolue Etbz Mp_xyl O_xyl MTBE CO,ppm Formal EtOH

Kitchen Ave-S 0.16 3.25 11.54 1.39 4.58 1.97 0.56 0.39 53.33 339.25

Ave-W 0.43 4.38 7.24 1.31 4.12 1.72 3.76 0.92 14.54

Garage Ave-S 1.87 8.72 20.36 3.06 8.67 3.51 2.47 1.82 26.44 17.35

Ave-W 2.35 8.15 14.44 2.54 9.00 3.39 36.64 6.45 18.72



# 4.3.3.3 Fuel and Vehicle Effects

This section addresses fuel, vehicle, a nd operational mode separately for all

seasons. For the sedan, Table 4.3-11 indicates highest mean MTBE values for Houston

fuel and EtOH for Chicago, as expected, with high-emitter/malfunction effects strongest

in the garage.

Table 4.3-11. Effect of Fuel and Operational Mode of the Sedan on Observed Levels in

the Kitchen and Garage (Units are ppbv, except as noted).

. Location Fuel Budi13 Benze Tolue Etbz Mp_xyl O_xyl MTBE CO,ppm Formal EtOH

Normal Garage Atlanta 0.55 2.40 6.09 0.98 3.24 1.38 0.82 0.31 7.16

Houston 0.95 3.56 9.78 1.51 5.20 2.08 10.81 0.56 22.25

Chicago 1.19 3.40 8.29 1.39 4.91 2.06 0.48 0.45 11.75 27.70

Kitchen Atlanta 0.06 2.01 8.42 1.03 3.61 1.45 0.10 0.10 63.45

Houston 0.24 2.82 7.49 1.10 3.69 1.59 3.35 0.52 24.01

Chicago 0.06 3.82 8.45 1.26 4.40 1.91 0.27 0.29 13.38 158.80

Malfunction Garage Atlanta 1.42 26.80 44.40 4.03 13.08 4.86 16.67 6.27 23.35

Houston 2.54 12.45 25.68 4.20 14.11 5.53 49.97 13.29 30.72

Chicago 1.92 9.54 11.26 1.65 5.64 2.18 1.13 12.16 13.08 19.00

Kitchen Atlanta 0.86 9.13 15.11 2.06 6.47 2.92 0.35 5.59 21.99

Houston 0.23 4.14 9.68 1.74 5.42 2.65 10.19 1.30 26.19

Chicago 0.23 2.81 6.04 1.03 3.51 1.53 0.30 0.76 25.93 670.20



## Budi13 = 1,3BD; Benze = benzene; Tolue = toluene, Mp_xyl = m,p-xylene; o_xyl = o-xylene,

Formal = formaldehyde; EtOH = ethanol



# For the truck, Table 4.3-12 indicates lesse r fuel impacts on normal mode garage

levels than for the sedan. For the malfuncti on mode, Houston fuel garage values exceed

those of the other two fuels.

Table 4.3-12. Effect of Fuel and Operational Mode of the Truck on Observed Levels in

the Kitchen and Garage (Units are ppbv, except as noted).

. Location Fuel Budi13 Benze Tolue Etbz Mp_xyl O_xyl MTBE CO,ppm Formal EtOH

Normal Garage Atlanta 2.40 11.28 26.45 3.79 11.05 4.32 0.44 2.13 38.17

Houston 1.39 9.69 24.99 3.83 11.12 4.46 10.46 2.15 38.12

Chicago 2.55 9.64 15.61 2.99 8.56 3.41 1.74 2.87 0.00 7.00

Kitchen Atlanta 0.12 1.65 8.23 0.83 2.58 1.04 0.10 0.28 35.68

Houston 0.37 4.57 9.68 1.62 4.85 2.28 7.20 0.82 45.47

Chicago 0.92 8.02 14.08 2.27 6.97 2.78 1.95 1.94 21.61 519.70

Malfunction Garage Atlanta 3.74 16.19 26.42 3.87 12.22 4.58 0.38 8.03 45.11

Houston 22.41 45.06 64.14 12.14 36.75 13.70 139.63 33.88 114.49

Chicago 2.73 7.72 11.55 1.85 5.87 2.16 0.06 2.52 32.96 5.80

Kitchen Atlanta 0.24 3.25 7.65 1.99 5.67 3.15 0.13 0.68 42.56

Houston 0.80 4.23 9.05 1.42 4.25 1.89 4.57 1.33 52.72

Chicago 0.11 4.11 7.29 1.45 4.67 1.92 0.03 0.28 29.37 414.10



# 4-9

# Figure 4.3-1 illustrates the effect of fuel and mode (N-normal, F-malfunction) on

mean garage values averaged across vehicl e and season. Figure 4.3-2 shows the kitchen

values. Both figures report relatively hi gh 1,3-BD values for the Houston fuel high

emitter mode. Since both are also associated with high MTBE values, these 1,3-BD

values are suspect as discussed earlier and in Chapter 1. The same caveat applies to

Figures 4.3-3 and 4.3-4.

0 10 20 30 40 50 60 70 80 90

Budi13 Benze Tolue Etbz Mp_xyl O_xyl MTBE CO,ppm Formal EtOH



### compoundppbv Atlanta-N

Atlanta-F

Houston-N

Houston-F

Chicago-N

Chicago-F



# Figure 4.3-1. Effect of fuel and mode on observed concentrations in the garage. The

legend “N” is normal and “F” is malfunction. Th e 1,3-BD value for Houston-F is suspect.

4-10

### 0 5 10 15 20 25 30 35 40 45 50

Budi13 Benze Tolue Etbz Mp_xyl O_xyl MTBE CO,ppm Formal EtOH



### compoundppbv Atlanta-N

Atlanta-F

Houston-N

Houston-F

Chicago-N

Chicago-F 

### 339,542



# Figure 4.3-2. Effect of fuel and mode on observed concentrations in the kitchen. The

legend “N” is normal and “F” is malfunction. The 1,3-BD value for Houston-F is suspect.

The kitchen concentrations are dom inated by HCHO and EtOH, but high

background levels indicate kitchen sources rather than the garaged vehicles.

The effect in the garage is expected to be more directly correlated with the

vehicle. Figure 4.3-3 shows the concentratio ns seen in the garage only for the sedan,

looking at the effect of the fuel and operati onal mode. The same presentation for the truck

only is in Figure 4.3-4.

4-11

### 0 10 20 30 40 50 60

Budi13 Benze Tolue Etbz Mp_xyl O_xyl MTBE CO,ppm Formal EtOH



### compoundGarage, ppbv Atlanta-N

Atlanta-F

Houston-N

Houston-F

Chicago-N

Chicago-F



# Figure 4.3-3. Effect of fuel and mode on observed sedan gara ge levels. The legend “N” is

normal and “F” is malfunction. The 1,3-BD le vel for Houston-F is suspect, see text.

0 20 40 60 80 100 120 140 160

Budi13 Benze Tolue Etbz Mp_xyl O_xyl MTBE CO,ppm Formal EtOH



### compoundGarage, ppbv Atlanta-N

Atlanta-F

Houston-N

Houston-F

Chicago-N

Chicago-F



# Figure 4.3-4. Effect of fuel and mode on observed truck gara ge levels. The legend “N” is

normal and “F” is malfunction. The 1,3-BD le vel for Houston-F is suspect, see text.

4-12

# 4-13 Comparison of 1,3-BD, BTEX and CO b ackground concentrations with garage

and kitchen concentrations for each test is shown in Figure 4.3-5 and Figure 4.3-6 for

Summer 2002 and Winter 2005, respectively. In general, these figures indicate

compound range rankings of garage » kitchen ~ background, especially for vehicle in the

normal mode. For vehicles in high emitting mode, the increase in kitchen levels could be

seen. In Winter 2005, a few high background sa mples were observed, possibly due to a

prolonged storage of a plastic gaso line container in the garage.050100150200250300350400 K-BACKG G -BACKG K-TE S T G -TE S T K-BACKG G -BACKG K-TE S T G -TE S T K-BACKG G -BACKG K-TE S T G -TE S T K-BACKG G -BACKG K-TE S T G -TE S T K-BACKG G -BACKG K-TE S T G -TE S T K-BACKG G -BACKG K-TE S T G -TE S T K-BACKG G -BACKG K-TE S T G -TE S T K-BACKG G -BACKG K-TE S T G -TE S T K-BACKG G -BACKG K-TE S T G -TE S T K-BACKG G -BACKG K-TE S T G -TE S T K-BACKG G -BACKG K-TE S T G -TE S T K-BACKG G -BACKG K-TE S T G -TE S T

ppbv05101520253035 CO (ppm )budi13mtbebenzetolueetbzmp_xylo_xylCOToyota,norm alToyota,m alfunctionAtlanta (Baseline) FuelTruck,norm alTruck,m alfunctionToyota,norm alToyota,norm alTruck,m alfunctionToyota,m alfunctionToyota,m alfunctioTruck,norm alHouston (M TBE) FuelTruck,m alfunctionTruck,norm alChicago (Ethanol) FuelFigure 4.3-5. Concentrations of 1,3-butadiene, MTBE and BTEX and CO as measured fromcanisters in the garage and the adjacentkitchen in Summer 20024-144-15050100150200250300 G-BACKG K-BACKG G-TEST K-TEST G-BACKG K-BACKG G-TEST K-TEST G-BACKG K-BACKG G-TEST K-TEST G-BACKG K-BACKG G-TEST K-TEST G-BACKG K-BACKG G-TEST K-TEST G-BACKG K-BACKG K-TEST G-TEST G-BACKG K-BACKG G-TEST K-TEST G-BACKG K-BACKG G-TEST K-TEST G-BACKG K-BACKG G-TEST K-TEST G-BACKG K-BACKG G-TEST K-TEST G-BACKG K-BACKG G-TEST K-TEST G-BACKG K-BACKG

ppbv G-TEST K-TEST051015202530354045 CO (ppm)budi13mtbebenzetolueetbzmp_xylo_xylCO_ppmAtlanta (Baseline) FuelToyota,normalToyota,malfunctionTruck,normalTruck,malfunctionHouston (M TBE) FuelToyota,normalToyota,malfunctionTruck,normalTruck,malfunctionChicago (Ethanol) FuelToyota,normalToyota,malfunctionTruck,normalTrumalfuck,nctioMMAFigure 4.3-6. Concentrations of 1,3-butadiene,MTBE and BTEX (A) and CO (B) as measuredfrom canisters in the garage and theadjacent kitchen in Winter 2005.M=sample missing or invalid.

# 4.3.3.4 Comparison with Emissions Data

There are five distinct garage scenario phases after the background sample as described

in Table 4.2-2. The first phase, hot soak, is best compared to the hot soak SHED test run by

SwRI. Benzene canister values are compared in Figure 4.3-7. While there does not appear to be a

strong correlation, the canister samp les collected in the garage aver age over all five scenarios,

not only hot soak. The high outlying points come from the truck in high emitter mode and are

expected to be high. SPME samp les taken every half-hour corre spond better with the phases of

the experiment. Benzene winter SPME values for hot soak phase are compared with SHED

values in Figure 4.3-8A (all sample s) and 4.3-8B (outliers removed). Although the correlation is

not very good for all samples (A), it improves af ter removing two outliers from the truck in high

emitter mode (B). The high emitting vehicles are ge nerally not stable and the SHED results may

be very different from the garage, due to different time and location.

0 10 20 30 40 50 60 70

0 20 40 60 80 100 120 140 160

SHED results, mgGarage, ppbv



# Figure 4.3-7. Comparison of SHED results with th e observed canister concen tration in the garage

for benzene.

0 5 10 15 20 25 30 35

0 20 40 60 80 100 120 140 160

SHED, mgGarage hot soak, ppbv (by SPME) y = 0.1317x + 4.8305

R 2 = 0.4323

0 5 10 15 20 25

0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0

SHED, MGGarage hot soak, ppbv (SPME) 

# B A

Figure 4.3-8. Comparison of the SHED results with the observe d SPME hot soak concentration

in the garage for benzene A: all data, B: two outliers removed.

4-16

# Cold start 1,3-BD and benzene canister values can be compared to the FTP Bag 1 data in Figures

4.3-9 and 4.3-10, respectively. Garage 1,3-BD values appear insensitive to FTP levels. It is

possible that this may reflect another 1,3-BD analytical challe nge from NO2 scavenging in the

FTP sample; the high point in Figure 4.3-7 is also suspect since 1,3-BD occurs concurrent with

high MTBE levels. The Figure 4.3-8 garage benzene scatter is similar to 1,3-BD and also appears

insensitive to FTP levels; however, benzene is st able in canisters and these values should be

accurate. Figure 4.3-11 compares garage SPME cold start values to FTP Bag 2 values. This

comparison trends upwards with garage valu es increasing with increasing FTP emissions,

although not strongly.

0 5 10 15 20 25 30 35 40

0 10 20 30 40 50 60 70 80

FTP Bag 1, mg/miGarage, ppbv



# Figure 4.3-9. Comparison of FT P Bag 1 emissions and observe d garage levels of 1,3-BD.

4-17

### 0 10 20 30 40 50 60 70

0 50 100 150 200 250

FTP Bag 1, mg/miGarage, ppbv



# Figure 4.3-10. Comparison of FTP Bag 1 benzen e emissions and observed garage levels.

0 10 20 30 40 50 60 70 80 90

0 20 40 60 80 100 120 140

FTP Bag 1, mg/miGarage, cold start, ppbv (by SPME)



# Figure 4.3-11. Comparison of hot soak FTP Ba g 1 benzene emissions and observed SPME

garage values.

4-18

# 4.3.3.5 Relationships of Garage and Kitchen Concentrations

Kitchen values would be expected to increase with increasing garage levels from vehicle

and fuel container sources. Based on thei r high background levels, Et OH and HCHO would not

be good candidates for tests. Three other specie s 1,3-BD, CO, and benzene are plotted in Figures

4.3-12, 4.3-13 and 4.3-14, respectively.

Figure 4.3-12A shows a weak 1,3-BD trend which seems to be driven mostly by outliers

associated with high level MTBE interference. As explained in Chapter 1 (page 1-6) elevated

MTBE concentrations biases measured 1,3-BD le vels upwards, due to the thermal decomposition

of MTBE (in the order of 1 to 5 %) in a GC in jector. The removal of tw o outliers (for the truck

with MTBE fuel in malfunction mode) eliminates any correlation between garage and kitchen

concentrations (Figure 4.3-12B).

Figure 4.3-13 trends toward a CO insensitivity to garage concentrations. The high value

occurred for the sedan in malf unction mode; the continuous data show a 100 ppm CO spike at

the beginning of the cold -start phase that may have penetr ated through a briefly opened kitchen

door. Figure 4.3-14 shows that there is no correlations between kitchen and garage benzene

concentrations. However, it has to be pointed ou t that these kitchen – benzene correlations are

shown for the time-integrated canister samples th at were collected over 2.5 hr duration of the

experiment. During this time several 30-min s cenarios were executed, as shown in Table 4-2.2.

The differences in ventilation conditions betw een garage and kitchen are the most probably

responsible for the lack of correlations between species measured from canisters.

y = 0.0298x + 0.2539

R 2 = 0.2034

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8

0 1 0 2 0 3 0 4 0 y = 0.0141x + 0.2965

R 2 = 0.002

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8

0123456

Garage Concentrations, ppbvKitchen Concentrations, ppbv B

Garage Concentration, ppbvKitchen Concentration,ppbv A



# Figure 4.3-12. Comparison of garage and kitchen concentrations for 1,3-BD. A – all data, Bwith two outliers re moved (see text).

4-19

## y = 0.04x + 0.84

R 2 

## = 0.05

0 2 4 6 8 10 12

0 10 20 30 40 5

Garage Concentration, ppbvKitchen Concentration,ppbv



## 0



# Figure 4.3-13. Comparison of garage and k itchen concentrations of carbon monoxide.

y = 0.04x + 3.61

R 2 

## = 0.06

0 2 4 6 8 10 12

0 2 0 4 0 6 0

Garage Concentration, ppbvKitchen Concentration,ppbv



## 8 0



# Figure 4.3-14. Comparison of garage and kitchen concentrations of benzene.

4-20

# 4.4 Discussion

The objective of this section was to test the effects of attached garage on indoor home

levels of fuel and exhaust components. The experiment simulates common activities such as

coming home with a warm car or leavi ng home after starting a cold vehicle.

Various parameters are assessed in section 4.3 to determine their eff ects on air levels in

the adjacent room (here a kitchen) connecting to the garage. Two target components, HCHO and

EtOH, had high kitchen background values indicating indoor sour ces of these materials.

Average HCHO levels were higher in summer than winter, consistent with enhanced off-gassing

of building materials and/or pe netration of ambient photochemical HCHO. It has been also

reported (Reiss et al, 1995; Wang and Morrison, 2 006; Weschler, 2006) that a larger fraction of

indoor HCHO and other oxygenated-low molecu lar weight hydrocarbons can result from

heterogeneous processes. Ozone originating from outdoors can be deposited onto indoor surfaces

and react with different materials to produce lo w molecular weight orga nic acids and aldehydes.

The concentrations of these species are higher during the summer when more ozone penetrates

indoors.

Tables 4.3-8 to 4.3-10 show a seasonal im pact where kitchen BTEX, MTBE and CO

species are higher in winter than summer. Th e exception is toluene which shows a minimal

difference that actually averages higher in summ er for normal mode vehicles. This is consistent

with indoor toluene emissions from paints, adhesi ves, cleaning, and personal care products.

Tables 4.3-8 and 4.3-9 focus on normal mode vehicl es to remove the variability of high emitter

modes in assessing the seasonal e ffect. Since many species higher in the winter come from both

evaporative and exhaust emissions, it is possible that winter enhanced fuel RVP contributes to

the apparent seasonal effect. In addition, a large number of studies have shown that home air

exchange rates are typically lowe r during the winter. This would result in longer residence times

(thus accumulation) of pollutants generated in th e garage and further inf iltration to the kitchen

area.

Tables 4.3-10 and 4.3-12 show vehicle data separately for each fuel. MTBE and ethanol

are highest for fuels containing t hose species, as anticipated. Otherw ise, there is not a strong fuel

effect across vehicles.

FTP exhaust and SHED evaporative emissions were tested for each vehicle, fuel, and

emissions mode, and compared to observed le vels in the garage. These comparisons are

challenging in that canisters integrate across hours covering not only hot so ak, adjustments to the

air exchange, and cold start. Concurrent SPME samples are collected for each condition.

However, neither canister nor SPME samples show strong correlations with hot soak emissions

(Figures 4.3-5 to 4.3-8), although cold-stabi lized FTP Bag 2 benzene appears reasonably

correlated to the cold-sta rt SPME (Figure 4.3-9).

Correlations of kitchen levels with garage concentrations are presented in Figures 4.3-12

to 4.3-14. These plots evidence weak correlations and could not be used to predict kitchen

exposures from garage levels. 1,3-BD (Figure 4.3-12) and benzene (Figure 4.3-14) may trend

weakly upwards, with kitchen levels increasing with garage levels; however CO (Figure 4.3-13)

4-21

# does not. Tables 4.3-6 and 4.3-7 indicate (HC HO & EtOH excepted) compound range rankings

of garage » kitchen ~ background, especially for vehicl e in the normal mode. For vehicles in

high emitting mode, the increase in kitchen levels is seen from Figures 4.3-5 and 4.3-6.

4.5 References:

Reiss, R., Ryan, P., Tibbetts, S. E., and Kout rakis, P., Measurement of Organic Acids,

Aldehydes, and Ketones in Re sidential Environments and their Relationship to Ozone, Journal of

the Air and Waste Manage ment Association, 45 , 811 (1995).

Wang, H., G.C. Morrison. Ozone-initiated seconda ry emission rates of aldehydes from indoor

surfaces in four homes. ES&T 40: 5262-68 (2006)

Weschler, C.J. Ozone’s impact on public health : contributions from indoor exposures to ozone

and products of ozone-initiated chemistry. Environ.Health Perspective 141: 1489-96 (2006).

4-22

# 5. Effect of Ventilation, Proximity, and Emission Levels on In-Cabin

Exposures of Trailing Vehicle.

5.1 Introduction

This chapter describes experiments de signed to determine the relationships

between ventilation, proximity, fuel, and emissi on levels of a leading vehicle on in-cabin

exposures within a trailing vehicle. The sa me vehicles, fuels and induced malfunctions

used for this chapter are used for Chapter 4. These measurements are part of the program

described in the executive summary and Chapter 1.

As in the preceding chapter, the vehicles used are a sedan and a pickup truck; the

fuels used are either a conventional fuel (without oxygenate), an ethanol fuel, or an

MTBE fuel. The vehicles are tested in a normal and induced-malfunction mode with nonmethane hydrocarbon (NMHC) emissions of ab out 2 g/mile by Federal Test Procedure

(FTP).

The experiments were performed in summer (June-July 2002) and winter

(February-March 2005).

5.2 Experimental

The Southwest Research Institute (S wRI) procured two test vehicles and

determined their evaporative/tailpipe emi ssions in the normal/malfunction modes using

the three test fuels. The test vehicles, a seda n and full-sized V8 truck, were chosen within

the 1993-1996 model years from vehicles with 90,000-110,000 odometer miles. The

chosen 1993 Toyota Camry (2.2L 4-cylinder engine) and 1995 Ford F150 Pickup truck

(5.0L V8 engine) were operated in normal, as purchased, modes and in “high emitter”

modes with the catalytic conve rter removed and emission levels above 2 grams per mile

NMHC as measured on the FTP driving cycle. While converter removal sufficed for the

F150 truck, a calibrated manifold leak was al so needed to achieve the 2g/mile Camry

emissions. SwRI determined dynamometer FTP emissions for each vehicle with all three

fuels in the two emission modes (24 tests). Emission control components could be

reproducibly adjusted to repr esent normal and reasonable high-end approximations (2

g/mile) of real world exhaust emissions. Test vehicle evaporative emissions were also

measured for test fuels in the two emi ssion modes as reported in Chapter 4.

Regulated exhaust emissions (THC , NMHC, CO, NOx), fuel economy, and

specific VOCs (MTBE, EtOH, BTEX, 1,3-BD , HCHO) were determined in the

dynamometer FTP tests. During hot-soak SH ED tests, THC and specific VOCs (minus

HCHO) were determined.

The FTP exhaust emission test uses the 1372 second Urban Dynamometer

Driving Schedule (UDDS) that is divided into cold/start transient 505 (Bag 1) and cold

stabilized 867 (Bag 2) second segments. This portion of the FTP is followed by a 10-

minute soak and a hot/start transient 505 (Bag 3) test. The FTP evaporative emission test

5-1

# includes one hour Diurnal Heat Build (DHB) and Hot Soak Loss (HSL) tests. THC/VOC

emissions are recorded during the HSL segment of the test. Prior to the FTP cold-start

exhaust test, the DHB is conducted by fueli ng the test vehicle to 40 percent of tank

capacity with fuel < 55°F, attaching a heat ing blanket outside th e fuel tank, placing a

thermocouple in the tank fuel, hooking it up to computer control, and beginning the test

as fuel reaches 60°F (increasing at 0.4°F per minute for the 60-minute test to a 84°F final

temperature).

In the HSL segment, conducted immediately following exhaust emission testing,

the vehicle is driven into an evaporative emi ssion enclosure and allowed to “soak” in the

enclosure for one hour. THC/VOC emissions ar e measured at the beginning and end of

the one-hour segment and hot soak evaporative emissions are calculated.

5.2.1 Fuel Testing

Test fuel samples were subject to standa rd tests for Reid Vapor Pressure (RVP),

distillation range, Specific Grav ity, Sulfur, Benzene, HC Category (saturates, olefins,

aromatics), Oxygenated species (MTBE/EtOH) , carbon weight percent, hydrogen weight

percent, oxygen weight percen t, and octane number. These results are presented in

Chapter 4, Table 4.3-1.

5.2.2 Relationship between Exhaust Emissi on Rates and In-Cabin Exposure -

Trailing Vehicle Test

5.2.2.1 Test Protocol

The two test vehicles were used as ch aracterized sources of measured in-cabin

exposures for an instrumented trailing vehi cle. SwRI procured a 1996 Chrysler Minivan

which DRI instrumented as the trailing vehicle (described in Chapter 1) that was driven

behind the test vehicles ove r a remote, paved, two-lane, farm-to-market roadway loop

(described below) for test periods up to 3 hours. Initial measurements made absent the

test vehicles established background levels. Trailing vehicle tests then implemented far,

near, and passing scenarios at low (30 mph) and high speeds (60 mph) as noted in Table

5.2-1. During 'far' scenarios, ‘safe’ vehicle sp acing (defined as one car length - 10 feet -

for each 10 mph) was maintained. During the 'near' scenario, the trailing vehicle

tailgated the lead vehicle, fo llowing at a close distance deemed 'safe' by the professional

drivers under prevailing traffic and meteor ological conditions. During the “passing”

scenario, the trailing vehicle split its time between tailgating the lead vehicle and

‘passing,’ immediately behind the l ead vehicle but in the adjacen t lane. A final idling test

was conducted while the trailing vehicle was parked on the road shoulder downwind and

closely behind the parked idling lead vehicle. High (10 min) and low (10 min) ventilation

conditions were used during a ll (including idling) tests.

Table 5.2-1 details the trailing vehicle pr otocol. Trailing vehicle in-cabin TVOC

[ppbRAE-PID (photoionization detector)], CO (Langan T15), BTEX (Kore200MS), and

HCHO (A- Ω ) were continuously monitored. Integrated VOC/NMHC (canister),

5-2

# HCHO/CH 3 

# CHO (DNPH cartridge), and EtOH (sorbe nt tube – EtOH fuel only) samples

were also collected. SPME BTEX samples were collected every 10 min. Appendix B

describes sampling and analyt ical methods in detail.

The trailing vehicle tests were conduct ed south of San Antonio, TX on county

roads 462 and 2779 off IH 35 in the vicinity of Moore, Big Foot, and Jones Mound,

Texas. The position of the trailing vehicle wa s recorded continuously by a Garmin 12XL

GPS unit recording in UTM using NAD83/WGS 84. Speed and direction of the vehicle

between any two points can be located on a ma p as illustrated in the June 19, 2002 test

Figures 5.2-1, -2. The mapping software also contains a digital elevation model that

creates elevation profiles as shown in Figure 5.2-3. The change in elevation over the

14.5-mile driving route is approximately 100 feet.

Table 5.2-1. Protocol for Trailing Vehicle Tests

Time

Min. Speed

Mph Ventilation

Setting Distance Notes Continuous

Instruments SPME Time

Integrated

10 high high background Y 1 1

10 low high far Y 1

10 low high near Y 1

10 low high passing Y 1

10 high high far Y 1

10 high high near Y 1

10 high high passing Y 1

10 low low far Y 1

10 low low near Y 1

10 low low passing Y 1

10 high low far Y 1

10 high low near Y 1

10 high low passing Y 1 One sample

in Summer

2002.

Two

samples, at

high/low

ventilation,

for Winter

2005.

10 idle low adjacent Y 1

10 idle high adjacent Vehicles:Toyota

Camry and Ford

Pick-up truck, in

normal and

malfunction mode.

Fuels: Atlanta

(conventional),

Houston (MTBE),

Chicago (ethanol)

Y 1 1

5-3

# Figure 5.2-1. Map of Driving Test Location n ear San Antonio. The bl ue markers indicate

the location of the driving tests.

5-4

# Figure 5.2-2. Map of Driving Test Location near Moore, TX.

Figure 5.2-3. Elevation Profile of the Driving Route near Moore, TX.

5-5

# 5.3 Results

An initial summary of the trailing ve hicle study findings, averaging across all

vehicles, emission modes, and fuels, is presen ted below. The lead vehicles and fuels are

the same as described in Chapter 4; Secti on 4.3.1 presents the fuel analyses and Section

4.3.2 the FTP exhaust and evaporativ e vehicle emissions tests.

Note the protocol changes between Su mmer 2002 and Winter 2005 tests: in the

Summer tests only half the sample days were begun with a background sample; in the

Winter tests separate in-cabin samples we re taken for the high ventilation and low

ventilation measurements as detailed in Table 5.2-1.

5.3.1 Background and Overall Concentrations

The background sample results from the summer and winter samples are

presented in Table 5.3-1. The percent standard deviations are relati vely low, suggesting

that the backgrounds are rela tively stable. The MTBE deviations are highest likely

because this compound is principally pres ent only in the Houston fuel. Background

MTBE ranged from 0 to 0.21 ppbv. There was only one EtOH background measurement

for the Summer 2002 (261 ppb) and three valid measurements for Winter 2005. The high

2002 EtOH value could be connected with the presence of four people in the vehicle

cabin and/or the presence of the continuous formaldehyde analyzer . The winter values

range from 9 to 44 ppb and seem to be more reliable.

Table 5.3-1. Summary of Su mmer and Winter Background Concentrations.

Budi13 Benze Tolue Etbz Mp_xyl O_xyl MTBE CO, ppm Formal EtOH

Mean Summer (n=6) 0.02 0.27 0.44 0.07 0.17 0.11 0.06 0.13 5.80 2

% std dev 53% 26% 15% 24% 46% 48% 131% 18% 84% (n=1)

Mean Winter (n=12) 0.03 0.33 0.60 0.12 0.43 0.19 0.07 0.22 5.76 22.07

% std dev 47% 43% 68% 62% 65% 69% 107% 36% 61% 88%

Mean all 0.03 0.31 0.55 0.10 0.35 0.16 0.07 0.19 5.78 81.

% std dev 50% 40% 62% 62% 77% 71% 111% 40% 67% 147% 61

80



## Budi13 = 1,3BD; Benze = benzene; Tolue = toluene, Mp_xyl = m,p-xylene; o_xyl = o-xylene,

Formal = formaldehyde; EtOH = ethanol



# In Figure 5.3-1 the values for formalde hyde are divided by 10 to fit on the same

scale as the rest of the species and the EtOH values are not shown. Generally speaking

the in-cabin background values are < 1 ppbv, with the exception of HCHO and EtOH,

and relatively consistent fr om summer to winter.

In-cabin HCHO measurements likely in cluded contributions from photochemical

formation from ambient VOCs and in-cabin fabric component degassing of this species.

As mentioned in Chapter 1 and 4, EtOH ma y be emitted from people (as a metabolic

product for certain food types), foods, cleaning& personal care products, etc.

5-6

# 5-7 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

Budi13 Benze Tolue Etbz Mp_xyl O_xyl MTBE CO, ppm FormaConcentration, ppbv or ppm

l/10

Mean Summer (n=6) Mean Winter (n=12)

Budi13 Benze Tolue Etbz Mp_xyl O_xyl MTBE CO, ppm Formal EtOH

Mean Summer (n=11) 0.50 1.17 2.01 0.36 1.07 0.49 0.38 0.85 6.78 2308.07

% std dev 111% 84% 70% 79% 77% 76% 269% 87% 50% 102%

Mean Winter (n=22) 0.48 1.01 1.75 0.32 1.11 0.43 0.31 1.36 4.32 1.49

% std dev 105% 81% 81% 85% 81% 84% 219% 91% 84% 48%

Mean all 0.49 1.06 1.84 0.33 1.10 0.45 0.34 1.19 5.14 770.35

% std dev 105% 81% 76% 82% 79% 80% 238% 93% 72% 214% 

# Figure 5.3-1. Comparison of Summer and Wi nter Background Concentrations with

Standard Deviations. HCHO is divided by 10 for scale.

Mean concentrations over all tests are presented in Table 5.3-2. Standard

deviations are expressed as a percent of test value. As with the background

concentrations, MTBE likely shows the greate st variability since it was prominent in only

one fuel. Also, EtOH Summer 2002 measurements (3 values) are most probably artifact,

whereas Winter 2005 data (6 measurements) seem to be much more reliable.

Table 5.3-2. Summary of Test C oncentrations for Su mmer, Winter and Overall. Units are

ppbv, except CO as noted.

Budi13 = 1,3BD; Benze = benzene; Tolue = toluene, Mp_xyl = m,p-xylene; o_xyl = o-xylene,

Formal = formaldehyde; EtOH = ethanol



# Figure 5.3-2 and 5.3-3 shows the CO, MTBE and BTEX concentrations for each

test in the Summer 2002 a nd Winter 2005, respectively.0102030405060 BACKG. TEST IDLE TEST IDLE TEST IDLE BACKG. TEST IDLE BACKG. TEST IDLE TEST IDLE TEST IDLE TEST IDLE BACKG. TEST IDLE BACKG. TEST IDLE BACKG. TEST IDLE TEST IDLE

ppbv024681012 CO (ppm)budi13mtbebenzetolueetbzmp_xylo_xylCOTruck,m alfunctionToyota,norm alToyta,m alfunctionTruck,norm alToyotam alfunctionTruckm alfunctioToyotanorm alToyota,m alfunctionTracknorm alToyota,norm al(M )Truckm alfunctionTruck,norm alAtlanta (Baseline) FuelHouston (MTBE) FuelChicago (Ethanol) FuelFigure 5-3-2. Concentrations of 1,3-BD, MTBEand BTEX (A) and CO (B) as measured inthe cabin of the trailing vehicle, Summer20025-85-9051015202530354045 BACKG TEST_HV TEST_LV IDLE BACKG TEST_HV TEST_LV IDLE BACKG TEST_HV TEST_LV IDLE BACKG TEST_HV TEST_LV IDLE BACKG TEST_HV TEST_LV IDLE BACKG TEST_HV TEST_LV IDLE BACKG TEST_HV TEST_LV IDLE BACKG TEST_HV TEST_LV IDLE BACKG TEST_HV TEST_LV IDLE BACKG TEST_HV TEST_LV IDLE BACKG TEST_HV TEST_LV IDLE BACKG TEST_HV

ppbv TEST_LV IDLE024681012 CO (ppm)budi13mtbebenzetolueetbzmp_xylo_xylCO_ppmAtlanta (Baseline) FuelToyota,normalToyota,malfunctioTrucknormalTruckmalfunctionToyota,normalToyota,malfunctioMTrucknormalTruckmalfunctionHouston (MTBE) FuelToyota,normalToyota,malfunctionTrucknormalTrmaChicago (Ethanol) FuFigure 5-3-3. Concentrations of 1,3-BD, MTBEand BTEX and CO as measured in thecabin of the trailing vehicle, Winter 2005

# Figure 5.3-4 compares summer and winter concentrations which, like background, are

similar (EtOH data not shown).

0 1 2 3 4 5 6 7 8

Budi13 Benze Tolue Etbz Mp_xyl O_xyl MTBE CO, ppm FormalConcentration, ppbv or ppm



### Mean Summer (n=11) Mean Winter (n=22)



# Figure 5.3-4. Comparison of Summer and Winter Concentrations for the Trailing tests.

Summer background and test values, excluding HCHO and EtOH, are compared

in Figure 5.3-5. Test values show a substa ntial increase over bac kground. Correlating all

summer species except HCHO and EtOH agains t their background valu es gives a slope

of 0.24 (r-square = 0.93).

Winter background and test values are presented in Figure 5.3-6, omitting HCHO

and EtOH. The observation that the winter HCHO values were, on average, lower than

background values suggests that most of the HCHO observed was not coming from the

lead vehicle but possibly from photochemical or off-gassing s ources (e.g., fabrics) inside

the trailing vehicle. EtOH background values were higher than test values, which suggest

some initial off-gassing of EtOH in the ve hicle cabin (since background sample was

collected at the beginning of each experiment). The correlation of all winter species

values except HCHO and EtOH against thei r background values had a slope of 0.31 (rsquare = 0.73).

5-100.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

Budi13 Benze Tolue Etbz Mp_xyl O_xyl MTBE CO, ppmConcentration, ppbv or ppm

Summer Background Summer Tests



# Figure 5.3-5. Comparison of Summe r Background and Test Values.

0 1 1 2 2 3 3 4

Budi13 Benze Tolue Etbz Mp_xyl O_xyl MTBE CO, ppmConcentration, ppbv or ppm

Winter Background Winter Tests



# Figure 5.3-6. Comparison of Winter Background and Test Values.

5-11

# Table 5.3-3 presents the concentrations a nd percent standard deviations observed

during the idle tests. These values showed more of a range and larger deviations than

either the background or the driving tests. HC HO again appears to be an outlier with the

lowest deviation of any of the species, likel y indicating that this species is not coming

predominantly from the upwind lead vehicle. EtOH values for Summer 2002 (3

measurements) are most probably artifact a nd the Winter 2005 values (4 measurements)

are more realistic. Since the main diffe rence between the Summer 2002 and Winter 2005

experiments was the absence of the c ontinuous formaldehyde and MS200 KORE mass

spectrometer in the trailing vehicle, it is possible that one of these instruments (most

probably the continuous formalde hyde analyzer, since it is based on the wet method) was

out-gassing EtOH.

Table 5.3-3. Summary of Concen trations Observed During Idle Tests. Units are ppbv

except CO as noted.

Budi13 Benze Tolue Etbz Mp_xyl O_xyl MTBE CO, ppm Formal EtOH

Mean Summer (n=11) 1.55 3.67 4.84 0.80 2.42 1.00 1.48 2.13 8.71 1030.68

% std dev 138% 114% 101% 106% 106% 99% 195% 156% 53% 59%

Mean Winter (n=22) 0.66 2.63 3.07 0.48 1.70 0.65 0.44 3.17 6.46 3.86

% std dev 162% 140% 140% 116% 117% 101% 200% 119% 42% 61%

Mean all 1.14 3.19 4.03 0.65 2.09 0.84 1.00 2.61 7.68 517.

% std dev 154% 123% 115% 112% 110% 102% 222% 134% 52% 131% 27



## Budi13 = 1,3BD; Benze = benzene; Tolue = toluene, Mp_xyl = m,p-xylene; o_xyl = o-xylene,

Formal = formaldehyde; EtOH = ethanol



# 5.3.2 Vehicle and Fuel Effects

The preceding section assessed overall mean concentrations in the trailing vehicle

cabin, averaging across vehicles, emission mode s and fuels; this section will separately

consider these parameters.

Table 5.3-4 details the effects of cha nging vehicle, fuel, and emission mode.

The first two rows distinguish the truc k and the car, averaged over all fuels and

modes. These values are very similar, showi ng little effect of the vehicle by itself.

The next three rows distinguish the fuel s, averaging over the vehicles and modes.

The Atlanta fuel results in higher BTEX c oncentrations in the trailing vehicle cabin,

which is consistent with higher aromatic cont ents of Atlanta fuel, especially in summer

(see Table 4.3-1).

The next two rows distinguish the normal and high emitter modes, averaging over

the vehicles and fuels. The values clearly di ffer, with the high emitter mode values much

higher than for the normal emitter mode.

The last line in this table presents th e percent standard de viations of the high

emitter values that are very similar, with the anticipated exception of MTBE which is

larger due to its predominant occurren ce in only one of the three fuels.

5-12

# Figure 5.3-7 presents the effect of no rmal versus high emitter vehicle on the

trailing vehicle in-cabin concentrations in a scatter plot for all species except HCHO and

EtOH. Cabin levels of HCHO and EtOH were omitted since in-cabin upholstery and

occupant sources of these compounds predominate penetration of outdoor levels. The

slope indicates that in-cabin values measured during trailing the vehicle in high emitter

mode are about twice those f ound for the normal mode. Since l ead vehicles in these tests

are converted between ‘normal’ and ‘high emitte r’ states by disabling control devices, not

by mis-tuning the engines or opening fuel line leaks, exhaust emissions should remain

roughly proportionate between both operational modes.

Table 5.3.4. Effect of Vehicle, Fuel, and Operational Mode. Un its are ppbv, except CO as

noted. Number of measurements = n

Vehicle, Fuel &

Mode Budi13 Benze Tolue Etbz Mp_xy

lene o_xyl MTB

E CO,

ppm Form

-al.

Truck only (n=12) 0.42 1.14 2.06 0.38 1.24 0.52 0.15 1.08 4.23

Car only (n=12) 0.59 1.13 1.87 0.33 1.11 0.45 0.53 1.42 6.13

Atl fuel only (n=8) 0.53 1.44 2.79 0.51 1.66 0.68 0.14 1.41 5.99

Hou fuel only (n=8) 0.56 1.05 1.63 0.35 1.19 0.50 1.28 1.10 5.88

Chi fuel only (n=8) 0.48 0.87 1.32 0.20 0.66 0.28 0.03 1.22 4.20

Normal only (n=12) 0.06 0.46 1.05 0.21 0.73 0.31 0.16 0.41 5.21

High emitter only

(n=12) 1.01 1.85 2.92 0.52 1.64 0.67 0.56 2.18 5.35

St Dev high emitter

only 26% 35% 40% 43% 43% 45% 199% 42% 55%



# y = 2.2228x + 0.4798

R 2 

# = 0.6929

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

0.0 0.2 0.4 0.6 0.8 1.0 1.2

Normal EmitterHigh Emitter



# Figure 5.3-7. Scatter plot of Normal Emitter and High Emitter Mean In-cabin Values for

all species except HCHO and EtOH.

5-13

# Looking at the high emitter mode only, Table 5.3-5 presents high emitter mean incabin values for each fuel separately. MTBE va lues present the clearest difference. This

is expected based on the fuel composition. Th e other species show relatively little

difference. EtOH values are not shown, due to th e Summer 2002 artifact.

Table 5.3-5. Influence of high emitting vehicles and each fuel on traili ng vehicle in-cabin

concentrations. Units are ppbv except CO as noted.

Mode, Fuel Budi13 Benze Tolue Etbz Mp_x

ylene o_xyl MTBE CO,

ppm Formal

High Emiter,

Atlanta (n=4) 1.02 2.35 3.97 0.67 2.12 0.85 0.03 2.48 5.04

High Emiter,

Houston (n=4) 1.18 1.76 2.65 0.61 1.98 0.82 2.63 1.82 5.81

High Emiter,

Chicago (n=4) 0.91 1.40 2.02 0.31 0.98 0.42 0.06 2.08 5.42



# The high emitter values, averaged across fuels, ar e presented in Table 5.3-6

separated by season. HCHO has the largest diffe rence, summer > winter, which is likely

due to more rapid photochemical reactions or in-cabin off gassing rates during the

summer. In addition, BTEX concentrations are consistently higher during the summer,

which is consistent with higher aromatic conten ts of summer fuels, especially for Atlanta

(see Table 4.3-1).

Table 5.3-6. Summary of Seasonal Differen ces in the High Emitter Samples.

Budi13 Benze Tolue Etbz Mp_xyl O_xyl MTBE CO, ppm Formal

Summer High 1.05 2.07 3.31 0.58 1.75 0.77 0.78 1.48 8.11

Winter High 0.98 1.74 2.73 0.48 1.58 0.62 0.45 2.54 3.96



# 5.3.3 Trailing Vehicle Effects

In the winter 2005 tests, separate canis ters were collected for the high and low

cabin ventilation portio ns of the tests; in the summer 2002 tests, only a single canister

was collected integrating these two periods . Table 5.3-7 shows the average values from

the high and low ventilation winter 2005 can isters. Their values are similar across

seasons. Table 5.3-7 shows that although mean can ister (integrated) in-cabin values were

similar under high and low ventilation conditions , the range of concentrations observed

by continuous PID monitor was much larg er under high ventil ation conditions, as

illustrated in Figure 5.3-8. The high ventilation condition co ntinues up to 60 min and is

then switched to low ventilation for th e remaining 60 min. The outdoor ppbRAE-PID

shows generally lower values and the two indoor peaks in the first 60 min are associated

with the “near” tailgating portion of the driving sequen ce. The outdoor PID2 shows

generally lower values that the indoor PID1, since it was mounted on the aerial on the

right side of the van, thus its inlet was mostly opposite to the truck’s tailpipe (that was

situated on the left side of the truck).

5-14ME0 - IN-CABIN TRUCK MAL BASE HV TEST 2/25 8:56

0 10 20 30 40 50 60 70 80

0 3 0 6 0 9 0

elapsed time (min)PID

1 2 0

PID1 PID2



# Figure 5.3-8. Time Series of In-Cabin (PID1) and Outside (PID2) PID Values. The first

60 min are under high ventilation conditions (0-60 min) and the next 60 min (60-120

min) are under low ventilation conditions.

Table 5.3-7. Comparison of High and Low In- cabin Ventilation Conditions, Winter 2005

only. Units are ppbv except CO as noted.

Budi13 Benze Tolue Etbz Mp_xyl O_xyl MTBE CO, ppm Formal

High Vent only 0.46 1.06 2.00 0.37 1.25 0.51 0.32 1.32 4.40

Low Vent only 0.55 1.06 1.69 0.30 1.08 0.41 0.33 1.52 4.46



# 5-15

# 5.3.4 Comparison with FTP Data

The driving tests were all conducted while the vehicle was in a hot stabilized

operating condition. The FTP test phase most co mparable is phase 2 (Bag 2) and this

section will examine the correlation of the Ba g 2 components with observed values in the

driving tests.

Figure 5.3-9 correlates Bag 2 and the tra iling vehicle benzene values. There is a

trend of increasing cabin benzene concentra tions with increasing benzene FTP emissions

(R 2 

# =0.64). Figure 5.3-10 presents the same correlation for MTBE although there are

fewer data points since only the Houston fu el contained substantial concentrations of

MTBE. Figure 5.3-11 illustrates the same correlation for 1,3-BD. Unlike benzene and

MTBE, 1,3-BD is primarily an exhaust co mponent. The 1,3-BD plot shows the same

correlation (R 2 

# =0.62) between the FTP emission leve l and the resulti ng trailing vehicle

cabin concentration as benzene. The correla tions are driven mostly by the vehicles in

malfunction modes, since only these vehicle em issions result in signi ficant concentrations

in the trailing vehicle cabin.

y = 0.02x + 0.55

R 2 

### = 0.64



## 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

0 20 40 60 80 100 120 14

FTP Bag 2 mg/miTrailing Veh, ppbv



## 0 Malfunction

Normal



# Figure 5.3-9. Comparison of FTP Bag 2 Benzene Emissions to In-cabin Concentration in

the Trailing Vehicle.

5-16

### y = 0.0367x + 0.5247

R 2 

### = 0.5041



## 0 1 2 3 4 5 6 7

0 20 40 60 80 100 120 140

FTP Bag 2 mg/miTrailing Veh, ppbv 

### Malfunction

Normal



# Figure 5.3-10. Comparison of FTP Bag 2 MTBE em issions to in-cabin concentrations in

the trailing vehicle.

y = 0.02x + 0.26

R 2 

## = 0.62



## 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6

0 1 0 2 0 3 0 4 0 5

FTP Bag 2 mg/miTrailing Veh, ppbv



## 0 Malfunction

Normal



# Figure 5.3-11. Comparison of FT P Bag 2 1,3-BD Emissions to In-cabin Concentrations

in the Trailing Vehicle.

5-17

# 5.4 Discussion

The overall objective of this section is to assess the various effects that might

impact trailing vehicle in-cabin levels of leading vehicle emissi ons. A rural test site with

very little traffic was chosen to minimize non-lead vehicle influences on measured incabin values. Background samples were taken pr ior to the driving tests to quantify other

possible sources. Measured component back grounds were low and consistent from

summer to winter although HC HO backgrounds were relative ly high, suggesting in-cabin

sources.

Summer and winter in-cabin values were similar in magnitude with the exception

of HCHO which was higher in the summer, possibly due to higher photochemical activity

and higher temperatures that le d to more HCHO off-gassing of the vehicle cabin interior.

EtOH values in Summer 2002 are much highe r than in Winter 2005, most probably due

to the off-gassing effect of the continuous fo rmaldehyde analyzer that was located in the

trailing vehicle cabin for Summer 2002 measurements.

Trailing vehicle cabin values were subs tantially larger than background values

except for HCHO which was actually lower than background in winter tests. Idle test

sample values were on average twice those en countered in driving tests, suggesting that

proximity and proximity duration may substa ntially impact in-cabin trailing vehicle

concentrations.

Average in-cabin levels were little aff ected by different vehicles or fuels except

for an MTBE fuel effect. However, aver aging over the fuels and vehicles, the high

emitter mode resulted in much higher traili ng vehicle in-cabin values than the normal

emitter mode, on average 2.2 times higher; except for HCHO which was relatively

unchanged from background. Similarly, the s eason had no strong effect upon the trailing

vehicle concentrations.

Trailing vehicle ventilati on status also affected in -cabin values. Although mean

canister (integrated) in-cabin values were simila r under high and low ventilation

conditions, the range of concentrations obs erved by continuous PID and CO monitors

was much larger under high ventilation. This may be rationalized as the vehicle moving

into and out of the exhaust plume of the l eading vehicle with in-cabin values changing

rapidly under high ventilation; whereas under low ventilation, in-cab in concentrations

trapped as the vents were closed stayed re latively constant during the remainder of low

ventilation conditions.

Trailing vehicle tests indicated that th e largest impact on in-cabin values came

from the emissions mode of the leading vehicl e. Emissions observed in Bag 2 of the FTP

tests were compared to the observed traili ng vehicle levels of benzene, MTBE and 1,3-

BD. Benzene and MTBE have both exhaust a nd evaporative emissions while 1,3-BD is

only emitted in exhaust. In-cabin benzene and MTBE levels appear to correlate with FTP

emissions, however, 1,3-BD does not but correl ates with other in-cabin species.

5-18

# APPENDIX A

APPENDIX B

APPENDIX C

APPENDIX D

APPENDIX E

APPENDIX F

APPENDIX G

APPENDIX H

APPENDIX I

1