SECTION 211(B) TIER 2 HIGH END EXPOSURE SCREENING STUDY OF BASELINE 

AND OXYGENATED GASOLINE –2ND RENO PILOT STUDY 

DRAFT REPORT 

Prepared for 

AMERICAN PETROLEUM INSTITUTE 

1220 L Street 

Washington, DC 20005-4070 

Prepared by 

Barbara Zielinska, John Sagebiel, David Campbell, Diana Ceballos, Mark McDaniel and Eric 

Fujita 

Desert Research Institute 

2215 Raggio Parkway 

Reno, NV 89512 
TABLE OF CONTENTS 

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

1.1 Study Overview and Technical Objectives ............................................................. 1-1 

2. Experimental Methods....................................................................................................... 2-1 

2.1 Measurement Approach........................................................................................... 2-1

2.2 Improvement in Sampling Platform........................................................................ 2-4 

2.3 Analytical Methods ................................................................................................. 2-6

2.3.1 Breath Samples Analysis ............................................................................... 2-6 

2.3.2 SPME Methodology ...................................................................................... 2-7 

2.4 Data Capture.......................................................................................................... 2-15

3. Results................................................................................................................................ 3-1 

3.1 Method Comparison of Redundant Data................................................................. 3-1 

3.1.1 PID versus PID .............................................................................................. 3-1 

3.1.2 NDIR vs. Electrochemical CO....................................................................... 3-7 

3.1.3 CO versus Canister CO................................................................................ 3-10 

3.1.4 MS vs. Canister............................................................................................ 3-12 

3.1.5 SPME vs. Canisters...................................................................................... 3-13 

3.1.6 SPME vs. MS............................................................................................... 3-17 

3.1.7 DNPH vs. Formaldehyde ............................................................................. 3-21 

3.1.8 Tenax vs. Canisters...................................................................................... 3-21 

3.2 Comparisons of Correlated Data ........................................................................... 3-23 

3.2.1 PID vs. CO................................................................................................... 3-23 

3.2.2 CO vs. Formaldehyde .................................................................................. 3-28 

3.2.3 SPME vs. PID.............................................................................................. 3-32 

3.3 Environmental Factors........................................................................................... 3-35

3.4 Reconstructed Data................................................................................................ 3-40

3.5 Breath Data............................................................................................................ 3-46

3.6 Consistency of Microenvironment Conditions...................................................... 3-51 

3.6.1 CO 3-51 

3.6.2 PID 3-53 

4. Conclusions........................................................................................................................ 4-1 

5. References:......................................................................................................................... 5-4 

6. Appendicies........................................................................................................................ 6-1 

6.1 Appendix A: SPME................................................................................................ 6-1 

6.2 Appendix B: Canisters and Tenax.......................................................................... 6-3 

6.3 Appendix C: Breath Samples ................................................................................. 6-9 

6.4 Appendix D: DNPH ............................................................................................. 6-12 

ii
LIST OF FIGURES

Figure 2.2-1. Van inlets ......................................................................................................... 2-5 

Figure 2.2-2. Inlets mounted on the tripod. ........................................................................... 2-5 

Figure 2.3-1. Set-up for temperature (upper panel) and relative humidity (lower panel) 

dependence measurements.............................................................................................. 2-9 

Figure 2.3-2. Temperature Dependence for 30, 50, and 100 ppb BTEX Concentrations. . 2-10 

Figure 2.3-2–cont’d. Temperature Dependence for 30, 50, and 100 ppb BTEX 

Concentrations. ............................................................................................................. 2-11 

Figure 2.3-3. Concentration calibration at a given temperature for the BTEX 

compounds.................................................................................................................... 2-11 

Figure 2.3-3-cont’d. Concentration calibration at a given temperature for the BTEX 

compounds.................................................................................................................... 2-12 

Figure 2.3-4. Dynamic Calibration Temperature Dependence............................................ 2-13 

Figure 2.3-5. Static Calibration Temperature Dependence (By interpolation from 

dynamic system)........................................................................................................... 2-13 

Figure 2.3-6. Humidity Dependence on SPME response for a 100ppb BTEX standard 

at 25C............................................................................................................................ 2-14 

Figure 2.4-1. Effect of driving on continuous formaldehyde analyzer, during and after

sampling in ME2-5. ...................................................................................................... 2-16 

Figure 3.1-1a. Comparison of estimated BTEX concentrations measured by PID 

instruments with inlets collocated within 10 cm. Data are running 1 minute

averages. VR = nozzle vapor recovery........................................................................... 3-2 

Figure 3.1-1b – cont’d. Comparison of estimated BTEX concentrations measured by 

PID instruments with inlets collocated within 10 cm. Data are running 1 minute 

averages. VR = nozzle vapor recovery........................................................................... 3-3 

Figure 3.1-2. Comparison of estimated BTEX concentrations measured by PID 

instruments during freeway driving tests. Data are running 1 minute averages............. 3-5 

Figure 3.1-2 –cont’d. Comparison of estimated BTEX concentrations measured by PID 

instruments during freeway driving tests. Data are running 1 minute averages............. 3-6 

Figure 3.1-3. Comparison of NDIR (API model 300) and electrochemical (Langan 

T15v) CO monitors during two freeway driving tests.................................................... 3-8 

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Figure 3.1-4. Comparison of two gas-filter correlation NDIR CO analyzers during onroad sampling.................................................................................................................. 3-9 

Figure 3.1-6 Comparison of canister and MS200 data for all measured species................. 3-12 

Figure 3.1-7. Comparison of MS200 and canister for benzene only................................... 3-13 

Figure 3.1-8. Scatter Plots for raw data from SPME vs canister for the Pilot Study 2003. 3-15 

Figure 3.1-9. Scatter Plots for temperature corrected SPME vs canister data for the Pilot 

Study 2003.................................................................................................................... 3-15 

Figure 3.1-10. Scatter plots from SPME vs Canister for the Pilot Study 2003 with two 

outliers removed. .......................................................................................................... 3-16

Figure 3.1-11. 10 minutes average MS data vs SPME benzene and toluene

concentrations: Freeway 5/02 7:35-8:15 am................................................................. 3-18 

Figure 3.1-12. 10 minutes average MS data vs SPME benzene and toluene 

concentrations: Freeway 4/30, 7:35 am........................................................................ 3-19 

Figure 3.1-13. 10 minutes average MS data vs SPME benzene and toluene

concentrations: Refueling w/o VR 5/02 9:18 am ......................................................... 3-20 

Figure 3.1-14 Comparison of canister and Tenax data for all ME ..................................... 3-22 

Figure 3.2-1. Comparison of CO and BTEX by PID during parking garage tests. ............ 3-24 

Figure 3.2-1 – cont’d. Comparison of CO and BTEX by PID during parking garage 

tests. Data are running 1 minute averages. ................................................................... 3-25 

Figure 3.2-3. Scatter plot of CO vs BTEX by PID during parking garage tests. Data are 

running 1 minute averages............................................................................................ 3-26 

Figure 3.2-4. Comparison of CO and BTEX by PID during freeway driving tests............ 3-27 

Figure 3.2-9. SPME 10 min total BTEX vs. PID 10 min averages, Freeway, 5/02, 7:35 

am ................................................................................................................................. 3-32 

Figure 3.2-10. SPME 10 min total BTEX vs. PID 10 min averages, Refueling w/o VR 

4/30 9:21am. ................................................................................................................. 3-32 

Figure 3.2-11. SPME 10 min total BTEX vs. PID 10 min averages, Freeway 4/30, 7:35 

am. ................................................................................................................................ 3-33 

Figure 3.2-12. SPME 10 min total BTEX vs. PID 10 min averages, Refueling w/o VR 

5/02 9:18 am. ................................................................................................................ 3-33 

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Figure 3.2-13. SPME 10 min total BTEX vs. PID 10 min averages, Parking Garage 5/06, 

16:45 pm. ...................................................................................................................... 3-34 

Figure 3.3-1. Fuel tank temperatures during freeway ME on 4/29/03. Ambient 

temperature was 4.4 C during this time. ....................................................................... 3-37 

Figure 3.5–1. CO2 values in the breath samples of subjects B and J collected in all ME, 

organized by the subject and by microenvironment..................................................... 3-47 

Figure 3.6-1. Range and variability of CO concentration during tests. Statistics for each 

of the five replicate tests are shown for each microenvironment. ................................ 3-52 

Figure 3.6-2. Range and variability of BTEX by PID concentration during tests.............. 3-54 

Figure 3.6-3. Range and variability of mean CO and mean BTEX by PID concentration 

for four microenvironments.......................................................................................... 3-55 

v
LIST OF TABLES 

Table 2.1-1. Measurement methods used in the 2nd Reno Pilot Study. ................................. 2-3 

Table 2.4-1. Data Capture Summary ................................................................................... 2-16 

Table 3.1-1. Data comparison between SPME and Canister.............................................. 3-14 

Table 3.1-2. Correlation of Scatter Plots from SPME and Canister Comparison............... 3-16 

Table 3.3-1. Environmental Conditions for Freeway Driving MEs. ................................... 3-36 

Table 3.3-2. Environmental Conditions for Garage MEs.................................................... 3-38 

Table 3.3-3. Environmental Conditions for Refueling MEs................................................ 3-39 

vi
1. INTRODUCTION 

The U.S. Environmental Protection Agency (EPA) has recently issued requirements for a test 

program in accordance with the Alternative Tier 2 provisions of the fuels and fuel additives 

(F/FA) health effects testing regulations, which are required pursuant to Section 211(b) of the 

Clean Air Act. In response to these requirements, the American Petroleum Institute (API)

contracted with a research team consisting of the Desert Research Institute (DRI), Southwest 

Research Institute (SwRI), Lovelace Respiratory Research Institute (LRRI), and TRJ

Environmental, Inc (TRJ) to conduct a screening study of the high-end distribution of

inhalation exposures to evaporative and combustion emissions of baseline- and oxygenated 

gasoline. The exposure protocols and measurement methods, sampling & analytical 

procedures are described in the June 13, 2002 Exposure Protocol and Study Plan. The field 

measurements in San Antonio, Houston, and Atlanta were completed in adherence to this 

written protocol during summer 2002. The work in Chicago was postponed pending further 

evaluation of the measurement protocol and assessment of the data collected to date. 

The overall approach for the exposure study is based upon the draft S211b Tier 2 Exposure 

Study Protocol that was developed in May 2001 by the API Section 211(b) Research Group 

and reviewed by the EPA. DRI and LRRI conducted a five-day pilot study in Reno, NV 

during February 2002 to test alternative measurement approaches in the field under 

conditions that are similar to those that will be encountered in the main study. TRJ and API 

provided input in the design of the pilot study and reviewed the results and findings. The 

evaluations included available measurement methods for continuous and time-integrated 

measurements of carbon monoxide (CO), total volatile organic compounds (TVOC), and 

designated VOC species. DRI and LRRI also evaluated the stability of the designated VOC 

species in breath and urine samples during the pilot study. Results of the pilot study are

summarized in our pilot study report (Zielinska et al., 2002). The draft exposure protocols 

were appropriately modified based upon the results of the pilot study. 

The work conducted last summer was summarized in two interim data reports, one reporting 

on data collected in San Antonio, Houston and Atlanta, and one conducting detailed data

analysis from Atlanta. Based on these reports, in order to assess and identify the necessity

for further refinement and adjustments to the study protocol prior to the commencement of 

the next phase of the study EPA asked to conduct the 2nd Pilot Study in Reno during the 

April – May 2003 time frame. 

1.1 Study Overview and Technical Objectives 

The main goal of the 2nd Reno Pilot Study was to demonstrate proper operation and 

reliability of analytical instrumentation and comparability of time-integrated, semicontinuous and continuous methods for compounds of interest. Four microenvironments

were selected for this study, as follows: 

1. Morning rush hour commuter traffic (ME1). This test was conducted on US395. 

Due to the limited rush hour period in Reno, a relatively small city, we sampled for 

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only 40 minutes. The driving route was from Parr Blvd in the north to Villanova Dr. 

in the south. During the test we attempted to follow a high emitting vehicle that was 

supplied by one of our DRI coworkers (Datsun 280Z, 1975). We sampled inside the 

van under high (first 20 min) and low (second 20 min) ventilation conditions. In low 

ventilation condition, we used recirculated air, windows closed, fan on high and in 

high ventilation conditions we had windows open, with fresh air, recirculated air off. 

During this ME a second PID monitored the air outside the van. 

2. Parking garage (ME2). Due to lack of a suitable below ground parking structure in 

Reno, we used an above ground parking garage. We selected the Galleria parking 

garage in downtown Reno, a site that is used by county workers in a nearby building 

whose workday ends at 5:00 PM. Consequently, this location had a pulse of cold-start 

traffic emissions at 5:00 PM as workers attempted to leave at the same time. Due to 

our limited city size and modest traffic density, we anticipated the evening exit rush

from the garage to be over promptly and employed one-half hour of sampling 

(approximately 1645 to 1715) from the van parked at a location near the only garage 

exit. Thus, all cars had to pass our sampling location as they exit the garage. The 

sampling inlet was located at the breathing zone immediately next to the van. 

3. Outdoor refueling with Stage 2 vapor recovery at the pump (ME3). We

conducted refueling of one vehicle (our 1996 sampling minivan) during a 20 min 

period. The fuel tank of the van was modified to enable the fuel to be drained from 

the van prior to refueling. Our objective was to dispense approximately the same

amount of fuel each time. The vehicle was driven prior to refueling to raise the 

monitored temperatures on the outside surface of the fuel tank. The refueling tests 

were performed at the service station in Reno (corner of Sun Valley Dr. and Dandini

Blv.), which has stage 2 vapor recovery nozzles. While removing the nozzle from the 

vehicle filler tube, we spilled a few drops of liquid gasoline on the ground near the 

vehicle. The amount of the spill was noted. The refueling was done under calm wind 

conditions (i.e., wind speed below 5 mph). Wind was monitored by hand-held 

anemometer. Monitoring was done at the breathing zone of the person fueling the 

van. 

4. Outdoor refueling without vapor recovery at the pump (ME4). This test was

conducted at a small gas station in Reno that does not have stage 2 vapor recovery 

nozzles. Because this station sells a relatively low volume of fuel, it has not been 

required to upgrade to the stage 2. As noted above, we refueled one vehicle during 

the 20 min test at the gas station. While taking the nozzle from the vehicle filler tube, 

we caused a spill of a few drops of liquid gasoline on the ground near the vehicle. The 

amount of the spill was noted. The refueling was done under calm wind conditions

(i.e. wind speed below 5 mph). Monitoring was done at the breathing zone of the

person fueling the van. 

Figure 1-1 shows the sampling locations. The US395 driving segment is marked in blue. 

1-2
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2. EXPERIMENTAL METHODS 

2.1 Measurement Approach 

Our sampling strategy consists of a three-tiered approach shown in Table 2.1-1, which lists 

the overlapping measurement methods used in the Section 211(B) Tier 2 High-End Exposure 

Screening Study and their intended application. The applications are classified in one of three 

tiers: reference, surrogate, and confirmatory. The base set or “reference” (R) measurements 

consist of three well-established time-integrated measurements. These include: 1) canister

sampling and analysis by gas chromatography with flame ionization detection for methanized

CO, BTEX, 1,3-butadiene, MTBE, and nonmethane hydrocarbons (NMHC); 2) 2,4-

dinitrophenylhydrazine (DNPH) cartridge sampling and analysis by high performance liquid 

chromatography with UV detection for formaldehyde and acetaldehyde; and 3) solid 

adsorbent sampling and analysis of ethanol by gas chromatography with mass spectrometry 

detection. These three methods combined measure all species of interest over the entire 

sampling period within each microenvironment. Although these integrated methods do not 

characterize peak exposures in microenvironments with highly varying exposure levels. They 

provide a basis for validating continuous and semi-continuous data. They also provide a basis 

for deriving correlations between the integrated values and continuous “surrogates” (S), such 

as CO and photoionizable VOC (10.6 eV - photoionization detector) PID data, in order to 

reconstruct their time series. For example, data for BTEX, 1,3-butadiene, and MTBE from 

the canister measurements can be correlated to continuous CO and PID data to reconstruct 

their time series in exhaust-dominated environments. The same method is used for ethanol 

and NMHC. In a similar manner, the time series of acetaldehyde and formaldehyde can be 

reconstructed from the correlation of the integrated DNPH samples with CO or PID. Outdoor 

afternoon samples should be excluded due to possible contribution of carbonyl compounds 

formed from atmospheric reactions of hydrocarbons. Table 2.1-1 shows the other correlations 

that can be used in this manner. 

Three continuous methods were employed to monitor: 1) the aromatic hydrocarbons benzene, 

toluene, ethylbenzene, and the xylenes (BTEX), 2) carbon monoxide, and 3) formaldehyde. 

These methods were also combined with component concentration ratios from 

contemporaneous time-integrated samples to reconstruct the expected time series for species 

that did not have continuous instruments, e.g., 1,3-butadiene (BD), ethanol (EtOH), and 

methyl tert-butyl ether (MTBE). 

The Kore MS200 instrument was used to monitor BTEX on a one-minute basis. This 

instrument uses a time-of-flight mass spectrometer to separate compounds of interest. This 

instrument also uses a software solution incorporating the 70 eV electron impact ionization

fragmentation patterns of each compound to apportion the contribution of each component of

interest to the time-of-flight (TOF) mass spectrum seen by the instrument. The software does 

not distinguish between specific isomers, thus xylenes are reported together. The inlet uses a 

polydimethylsiloxane membrane preferentially to allow non-polar organic compounds into 

the analyzer while maintaining the vacuum inside the analyzer chamber. This membrane inlet 

2-1
does limit the types of compounds that can be analyzed, however. Common air constituents

and polar organic molecules do not pass the membrane quickly. 

Carbon monoxide was monitored by the Langan T15 CO monitor and the API Model 300 

and ML9830 CO NDIR analyzers. The Langan T15 is an electrochemical monitor for CO. 

The response time of this instrument is somewhat slower than infrared-based instruments. 

Both the API and ML instruments are specified in the EPA List of Designated Reference and 

Equivalent Methods (March 24, 2000) as a federal reference method operating at any 

temperature in the range of 15 oC to 35 oC (59 oF to 95 oF). 

(www.epa.gov/ttnamti1/files/ambient/criteria/criteria/0300co.pdf) 

Continuous Formaldehyde Monitor (Alpha-Omega Power Technology, Ltd., Albuquerque, 

NM) absorbs formaldehyde in acidified water, reacting it with 2,4-pentanedione and 

ammonia to form a cyclized product, 3,5-diacetyl-1,4-dihydrolutidene, which is continuously 

detected by fluorescence. The method is highly specific for formaldehyde and very sensitive. 

However, since this instrument did not performed well during the summer study we

introduced several improvements, as follows. The original instrument case, detector, 

electronics, valves, some of the fittings were retained. Major modifications included removal 

of the original four channel peristaltic pump necessary for reagent delivery and fluid flows to 

the detector. This pump was found to be incapable of maintaining consistent flows and was 

susceptible to failure when pump tubing would rupture or pull away from the connection 

fittings. In addition, flow rates had limited adjustability, making it not suitable for the 

additional modifications that were performed on the instrument. The peristaltic pump was 

replaced with four milliGAT piston pumps (Global FIA) with microprocessor-controlled 

motors capable of delivering a broad range of precisely metered flow rates. Another major

modification was replacement of the diffusion scrubber assembly with a scrubbing coil 

similar to the design described in Kelly and Fortune (1994). The original diffusion scrubber

was susceptible to malfunction when scrubbers or driers were heavily used or contaminated 

by the reagents. In contrast, the scrubbing coil is simple to operate and maintain, and is

reported as being 100% efficient at removing gaseous formaldehyde from the air stream

being sampled. An in-line debubbler (Global FIA) was installed between the heated reaction 

cell and the detector to remove any bubbles from the sample stream before entering the 

detector. This was necessary because bubbles may be generated elsewhere in the system or

when the sample mobile phase is heated in the reaction cell. Finally, calibration of the 

instrument was performed using a gaseous formaldehyde standard (1 ppm in N2(g),ApelReimer) diluted to the desired concentration (5 to 250 ppb) with UHP zero air (Airgas) and 

plumbed to the sample inlet of the scrubbing coil. Calibration curves were linear (R2

>0.99). 

The instrument response time was determined to be 6 minutes from the time of sample 

introduction to equilibration at the detector. Instrument background was determined by 

periodically installing a DNPH cartridge (Waters) on the inlet of scrubbing coil to remove

any formaldehyde from the sample stream in order to observe the detector baseline response. 

 

2-2
Table 2.1-1. Measurement methods used in the 2nd Reno Pilot Study. 

Data applications for specific methods are classified as reference, confirmatory, and surrogate. 

A

1

Continuous Semi-Cont I

Method T15 CO NDIR CO ppbRAE MS200 HCHO SPME Canister 

pplicable Environments all all all higher end all all all 

Time Resolution seconds seconds seconds 1 min 1-2 min 10 min 30 & 40 min 30 Detection Limits 0.1 ppm 0.04 ppm 1 ppb 1-3 ppbv 1 ppbv 0.2 ppbv 0.05 ppbC Data Application 1 S S S C C CR

CO SC SC RPID 2 SC

BTEX S (a) S (a) SC (c) C C R

,3-Butadiene S (a) S (a) S (c) R

MTBE S (a) S (a) S (c) C RFormaldehyde S (b) S (b) S (d) C Acetaldehye S (b) S (b) S (d) S (g) Ethanol S (e) S (e) S (f) 

NMHC S (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 ratio for exhaust-dominated samples except outdoor daytime samples.S (c). Time series will be reconstructed from the canister/PID ratio for exhaust- or evap-dominated samples in outdoor MEs.S (d). Time series will be reconstructed from the DNPH/PID ratio for 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.

S (g). Time series will be reconstructed from CH3CHODNPH/HCHOCont ratio for exhaust dominated samples.

2-3
Photoionization detector (PID) measured the total signal from molecules ionizable at 10.6 

eV. We used two PID monitors for the pilot study. For the freeway runs, one PID sampled 

outside air, and the other sampled in-cabin air. For the remaining runs, only one PID was 

used, but for comparison purposes we ran both of them side-by-side for selected runs. 

The time-integrated and semi-continuous collection methods (canisters, solid adsorbent 

cartridges, DNPH-integrated cartridges and SPME) were described in detail before (Zielinska 

et al, 2002, 2003). Depending on the type of sorbent (C18 or silica gel) in the DNPH 

cartridge, the carbonyl compound ambient measurement results are subject to various 

artifacts due to interaction with ozone. Consequently, the ozone denuder is recommended for 

sample collection. For this pilot study, we used a honeycomb denuder coated with sodium 

carbonate/sodium nitrite/glycerol mixture (method developed by Dr. Koutrakis from the

Harvard School of Public Health). For canister sampling, ambient NO2 is of concern, since 

it might react with 1,3 butadiene. Thus, we were using a honeycomb denuder coated with 

triethanoloamine (TEA) to remove NO2 (a method developed by Dr. Koutrakis). 

In addition, we collected breath samples in all microenvironments. We used 1 liter silicosteel 

canisters (Restek, Inc.) and a collection method described by Pleil and Lindstrom, 1995. 

Breath samples were collected for the refueling MEs immediately before and 10 seconds 

after refueling the vehicle to provide an estimate of the highest cumulative exposure. For the 

commuter traffic and garage MEs, breath samples were collected before, and at 10 seconds 

after a peak exposure indicated by the PID, and at the end of the ME sampling time. Two 

breath samples were collected at refueling MEs (total of 20) and three during each commuter 

traffic and garage tests. This is a total of 50 breath samples. The CO2 level in the breath 

sample of persons conducting the breath test was measured prior to the pilot study. 

2.2 Improvement in Sampling Platform 

The most significant change made to the sampling platform was the combination of all 

sampling inlets at a single location. For the mobile ME (freeway driving), the inlets are all 

located in the breathing zone near the driver’s right shoulder. Figure 2.2-1 shows the current 

configuration of the inlets. The line in this figure labeled “Sample Inlet” provides sample to 

the NDIR CO, the MS200, the formaldehyde instrument, one of the two PIDs and all of the

integrated samplers (canister, DNPH and solid adsorbent). The SPME fiber, the main inlet 

and the temperature and relative humidity sensor are all within 3 cm of each other. The T-15 

(electrochemical) CO instrument is also very close. This configuration was designed to 

minimize or eliminate potential variability associated with concentration gradients inside the

van. In addition, we recorded the fuel tank temperature by way of a temperature probe 

secured to the outside of the fuel tank and insulated to prevent influence from the ground or 

air heat. The video camera recorded the view out the front windshield during the driving ME 

and was used to record other significant activity at the other MEs. For example, in the

garage, the camera was used to record traffic driving by the sampling point. 

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Figure 2.2-1. Van inlets 

For the stationary MEs (refueling and garage), the inlet was mounted on a tripod to allow for 

placement at an appropriate location outside the van. In this case, the temperature and 

relative humidity probe was relocated as well. This was accomplished by an additional piece 

of Teflon tubing for the inlet and an extension cable for the temperature and relative 

humidity probe. This allows the sampling system to be switched from one configuration to 

the other relatively quickly without disturbing the instruments and samplers. Figure 2.2-2 

shows a close-up of the tripod and details the locations of the sample inlet, the T/RH probe, 

and the SPME fiber. The proximity of all three ensures that no small-scale variations in 

concentration are influencing the sample. 

Figure 2.2-2. Inlets mounted on the tripod. 

In addition, there were several other modifications made to the van to improve it for the 

sampling program. Among these were the addition of racks to safely and securely hold the 

equipment, the upgrading of the power supply, and the addition of a pump and lines to 

2-5
withdraw the fuel from the fuel tank in between the refueling MEs. A computer-based data 

acquisition system was also installed to acquire as much of the data as possible in one 

system. This was used to log all temperature and other environmental parameters, analog 

outputs from the CO instruments and the formaldehyde instrument, and position, speed and 

direction information from the GPS unit. 

The power system was significantly upgraded to provide power and to eliminate the 

suspected artifact seen on the T-15 CO under low ventilation conditions. In these 

experiments, no artifact was observed on the T-15 CO monitor, and thus we are confident 

that this potential contamination has been eliminated. However, the power system proved 

incapable of providing enough power for the API NDIR CO monitor. Once we discovered 

what was wrong (the instrument did not give an error message, rather it began giving very 

erratic results), we added a set of lead-acid batteries outside the van to provide the power 

necessary to supply this one instrument. 

2.3 Analytical Methods 

Most of the analytical methods employed during this pilot study were described in detail 

before (Zielinska et al., 2002a,b; 2003). The exceptions are the analysis of the breath 

samples that was performed similarly to the method of Pleil and Lindstrom, 1995, by gas 

chromatography/mass spectrometry (GC/MS), and the determination of the dependence of

SPME concentrations on temperature and relative humidity. The sections below describe

these two analytical procedures. 

2.3.1 Breath Samples Analysis 

The GC/MS system included: Entech 7100 preconcentrator, Varian 3800 gas chromatograph 

with FID and column switching valve, and Varian Saturn 2000 ion trap mass spectrometer. 

The Entech preconcentrator consisted of three traps: 50% glass beads/50% Tenax, held at –

100 °C during sample transfer, 100% Tenax held at –40 °C and a final focusing trap (a piece 

of silico-steel capillary) held at –180 °C. The sample is desorbed from the first trap at 10 °C, 

from the second trap at 200 °C and from the third one at approximately 70 °C to a transfer 

line heated to 110 °C and connected to the head of the first column. The sample was injected 

at the head of a 60 m x 0.32 mm polymethylsiloxane column (CPSil-5, Varian, Inc.) held at 

30 °C. This column was connected to the switching valve leading into a 30 m x 0.53 mm GSGasPro column (J&W Scientific). After approximately 7 min the valve was switched so that 

the effluent from the first column eluted onto a second 15 m x 0.32 mm polymethylsiloxane 

column connected to the mass spectrometer. The column switch was timed so that the C2 and 

C3 compounds eluted on the FID and all C4 and higher compounds eluted on the mass 

spectrometer. The GC program was as follows: 30 °C held for 2 min, then 8 °C/min up to 

260 °C. 

Calibration of the system was conducted with a mixture that contained the most commonly 

found hydrocarbons (75 compounds from ethane to n-undecane, purchased from Air 

Environmental), MTBE, and halocarbons (23 compounds from F12 to the dichlorobenzenes, 

purchased from Scott Specialty Gases). The standards were prepared in 6 L Silco-Steel 

2-6
canisters (Restek, Bellefonte, PA) by mixing three different standards through a multi-valve 

manifold using a Baratron absolute capacitance manometer (MKS Instruments, Andover, 

MA) to determine the pressure each standard added to the mixture. Prior to mixing, 

approximately 0.2 ml of ultrapure water was added to the canister to humidify the mixture

(for mixture stability). The concentrations in the mixture were in the range of 0.2 to 10 ppbv. 

Three point external calibrations were run prior to analysis, and one calibration check was

run every 24 hours. If the response of individual compounds were more then 10% off, the 

system was recalibrated.

Carbon dioxide (CO2) from breath samples was determined using GC/FID. Since the FID 

does not respond to CO and CO2, these species are converted to methane by a methanator, 

positioned after the GC column, but ahead of the FID. The methanator comprises a firebrick

powder impregnated with nickel catalyst, through which a stream of hydrogen gas flows

continuously at ~550 °C. For compound separation, a 20-foot x 1/8-inch inner-diameter (i.d.) 

column, packed with a 60/80 mesh of Carboxen 1000 (Supelco) is used. This column 

provides sufficient separation between CH4 and CO, without retaining CO2. Five ml

samples were injected using a constant volume loop. The minimum detection limit for both 

CO and CH4 is ~20 ppbv, whereas for CO2 it is ~3 ppmv. The precision of measurements is

generally better than 10%. 

2.3.2 SPME Methodology 

During the Reno 2nd pilot project, SPME fibers were calibrated and analyzed as described 

before (Zielinska et al, 2002, 2003). However, the gas calibration had to be corrected for 

temperature, since static (Tedlar bag) calibration is performed at room (25o C) temperature 

and the sampling temperature ranged from 4o C to 30o C (average 16o C). At lower 

temperature the fiber uptake is higher, therefore SPME values were expected to be higher 

than canister data. The temperature correction factors were obtained experimentally in the 

laboratory in a dynamic flow-through system constructed for the control of temperature and 

humidity of certified BTEX standards. Humidity corrections are not addressed in this report 

because the experimental data obtained so far doesn’t show a significant change in the SPME 

response due to the change in humidity. 

2.3.2.1 Temperature and Humidity Calibration Experimental Setup 

Figure 2.3-1 shows the experimental setup for temperature and humidity calibration. It 

consisted of a 1L glass bulb that had two stopcocks on each side to let the calibration gas 

flow through and an injection port covered with a sleeve septum to allow the introduction of 

a SPME fiber. The bulb was temperature controlled with a cooling/heating system. The 

temperature inside the glass bulb was measured with a thermocouple. For introducing the 

desired humidity, a heated injection port was added before the glass bulb entrance in order to 

inject water with a syringe pump (Harvard Apparatus), Ludovic et al., 2001; Nelson, 1992;

McLaren and Zhou, 2000; Martos and Pawliszyn, 1997). The water-dispensing rate can be 

calculated from the theoretical saturation ratio obtained from a skew T diagram:

RH = 100 w/ws 

2-7
ws = ws(T,P) 

w is set with the water-dispensing rate as g water/Kg air=RH*ws/100 

The experimental humidity was measured with a humidity sensor (Dickson FH121). 

Data from the static calibration was compared to the data obtained in the dynamic system to

determine a correction factor that could be applied to the sampling data. Tedlar bag 

calibrations are valid for the type of environments we are measuring where wind should not 

exceed 4 miles/hour. However, temperature calibration is a better approached in a dynamic 

system because temperature is the only variable that changes, while in a static system 

pressure and volume must be adjusted as explained by the ideal gas law and makes the 

system very imprecise. Some advantages of a dynamic system are greater reproducibility and 

stability of the standards at lower concentration ranges (Nelson, 1992; Lodge 1984). 

2-8
Figure 2.3-1. Set-up for temperature (upper panel) and relative humidity (lower panel) 

dependence measurements 

2-9
2.3.2.2 SPME Temperature Dependence 

PDMS coating has a small decrease in the response of organics for samples with relative 

humidity close to 100%. The primary experimental parameter that control the response is 

temperature. In theory, the effect of temperature on the distribution constant can be

predicted, since log(Kfg) is linear with 1/T and the heat of vaporization of the pure solvent 

(Kfg – partition coefficient). In other words, Kfg can be calculated for the given sampling 

conditions (Pawliszyn, 2002). This theoretical approach is based on the liquid properties of

the PDMS coating in the fiber. However, in practice the theory doesn’t satisfactorily match 

the experimental values. Therefore, we performed more experiments and utilized the 

experimental approach. 

Standards were measured at different temperatures using the dynamic system described 

above and results were compared to those obtained in a room temperature static calibration. 

The experiments were performed at different BTEX concentration levels, as shown in figure 

2.3-2. 

Temperature dependence for 30 ppb BTEX

0

2000

4000

6000

8000

10000

12000

14000

0 10 20 30 40 50

Temperature (C)

Area Counts

Benzene Toluene Ethylbenzene m,p-xylene o-xylene

Temperature Dependence for 50 ppb BTEX

0

4000

8000

12000

16000

20000

0 5 10 15 20 25 30 35 40 45

Temperature, C

Area Counts

benzene toluene ethylbenzene m,p-xylene o,xylene

Figure 2.3-2. Temperature Dependence for 30, 50, and 100 ppb BTEX Concentrations. 

2-10
Temperature Dependence for 100 ppb BTEX

0

5000

10000

15000

20000

25000

30000

0 10 20 30 40 50

Temperature, C

Area Counts

bezene toluene ethylbenzene m,p-xylene o-xylene

Figure 2.3-2–cont’d. Temperature Dependence for 30, 50, and 100 ppb BTEX 

Concentrations. 

These data can be plotted by temperature in order to obtain a linear relationship with 

concentration as in Figure 2.3-3. 

Benzene Temperature Dependence

y = 188.38x

R2 = 0.7134

y = 128.92x

R2 = 0.5189

y = 107.17x

R2 = 0.7398 0

5000

10000

15000

20000

25000

0 20 40 60 80 100 120

Concentration, ppb

Area COunts

10 C 25 C 40 C

Linear (10 C) Linear (25 C) Linear (40 C)

Toluene Temperature Dependence

y = 178.81x

R2 = 0.9227

y = 127.49x

R2 = 0.784

y = 99.57x

R2 = 0.5472

0

5000

10000

15000

20000

0 20 40 60 80 100 120

Concentration, ppb

Area COunts

10 C 25 C 40 C

Linear (10 C) Linear (25 C) Linear (40 C)

Figure 2.3-3. Concentration calibration at a given temperature for the BTEX compounds. 

2-11
Ethylbenzene Temperature Dependence

y = 85.481x

R2 = 0.7776

y = 63.1x

R2 = 0.3382

y = 46.488x

R2 = 0.6668

0

2000

4000

6000

8000

10000

0 20 40 60 80 100 120

Concentration, ppb

Area C

Ounts

10 C 25 C 40 C

Linear (10 C) Linear (25 C) Linear (40 C)

m,p-xylene Temperature Dependence

y = 153.11x

R2 = 0.7653

y = 108.77x

R2 = 0.6097

y = 84.309x

R2 = 0.6317

0

5000

10000

15000

20000

25000

30000

35000

0 50 100 150 200 250

Concentration, ppb

Area C

Ounts

10 C 25 C 40 C

Linear (10 C) Linear (25 C) Linear (40 C)

o-xylene Temperature Dependence

y = 230.24x

R2 = 0.8262

y = 148.82x

R2 = 0.8426

y = 116.78x

R2 = 0.8967 0

5000

10000

15000

20000

25000

0 20 40 60 80 100 120

Concentration, ppb

Area COunts

10 C 25 C 40 C

Linear (10 C) Linear (25 C) Linear (40 C)

Figure 2.3-3-cont’d. Concentration calibration at a given temperature for the BTEX 

compounds. 

2-12
Furthermore, we plotted the slopes from this linear relationship vs. temperature in order to 

analyze the SPME response for a given temperature. Figure 2.3-4 shows the linear 

relationship between the slopes at different temperatures. 

y = -3.7813x + 259.81

R2

 = 0.9405

y = -2.2933x + 172.73

R2

 = 0.9731

y = -1.2997x + 97.515

R2

 = 0.9928

y = -2.6413x + 201.32

R2

 = 0.9718

y = -2.707x + 209.17

R2

 = 0.9329

0

50

100

150

200

250

0 5 10 15 20 25 30 35 40 45

Temperature (C)

 Slope (AC/Conc)

benzene toluene ehtlybenzene m,p-xylene o-pylene

Linear (o-pylene) Linear (m,p-xylene) Linear (ehtlybenzene) Linear (toluene) Linear (benzene)

Figure 2.3-4. Dynamic Calibration Temperature Dependence 

From this dynamic temperature calibration we correlated the three variables analyzed (such 

as area counts, temperature, and concentration) and calculated the concentration of the

sample by the area counts from the analysis and the sampling temperature. Furthermore, we 

compared the 25C dynamic and static calibrations and extrapolated the other temperature 

GC/PID responses in obtaining figure 2.3-5. 

y = -1.1463x + 78.761

R2

 = 0.9405

y = -0.5057x + 37.946

R2

 = 0.9928

y = -0.8207x + 61.813

R2

 = 0.9731

y = -0.7906x + 60.259

R2

 = 0.9718

y = -0.8336x + 64.411

R2

 = 0.9329

0

10

20

30

40

50

60

70

80

0 10 20 30 40 50

Temperature, C

Sl

o

p

e (

AC/C)

benzene toluene ethylbenzene m,p-xylene o-xylene

Linear (o-xylene) Linear (ethylbenzene) Linear (m,p-xylene) Linear (toluene) Linear (benzene)

Figure 2.3-5. Static Calibration Temperature Dependence (By interpolation from dynamic 

system) 

2-13
The equations that result from these extrapolations are the following: 

STATIC SYSTEM (INTERPOLATED FROM DYNAMIC SYSTEM)

 

Component equation correl Concentration

benzene y = -0.8336x + 64.411R2 = 0.9329AC/( -0.8336T+64.411)

toluene y = -0.7906x + 60.259R2 = 0.9718AC/( -0.7906T+60.259)

EtBenzene y = -0.5057x + 37.946R2 = 0.9928AC/(-0.5057T+37.946)

m/p-xylene y = -0.8207x + 61.813R2 = 0.9731AC/( -0.8207T+61.813)

o-xylene y = -1.1463x + 78.761R2 = 0.9405AC/(-1.1463T+78.761)

 

 AC/C=aT+c

 C=AC/(aT+c) 

2.3.2.3 SPME Humidity Dependence 

Chai and Pawliszyn, 1995, performed several experiments in order to determine the influence

of humidity for the 100 μm PDMS response factor. Humidity usually decreases the response 

factor of each individual compound. The lower response depends on temperature. At lower 

temperatures, the humidity has a larger decrease in the response factor of a compound. Some

compounds are not greatly affected by humidity. The highest effect of humidity seems to be 

an approximately 25% decrease when going from dry air at 0C-10C into 25% relative 

humidity. Changes of the area counts at ranges of temperature of 0C-25C for changes in 

relative humidity from 25%-75% are almost negligible (also discussed by Parreira et al, 

2002). 

It is understood that humidity affects the fiber response because water at high concentrations 

is completely adsorbed into the coating of the fiber. 

Initial data from the experimental set up described earlier is shown below: 

0

5000

10000

15000

20000

25000

0 10 20 30 40 50 60 70 80

Relative Humidity (%)

Area Counts

Benzene Toluene ehtylbenzene m,p-xylene o-xylene

Figure 2.3-6. Humidity Dependence on SPME response for a 100ppb BTEX standard at 

25C. 

2-14
Current experiments at 25C determined that humidity in the BTEX compounds does not 

affect the GC/PID response significantly, although is lowers the response slightly at RH > 

75% . 

2.4 Data Capture 

The overall data capture rate for all the 2nd Reno Pilot Study measurements is provided in 

Table 2.4-1, with the complete details for each ME presented in Appendix A. Overall the

data capture for the integrated methods was nearly complete . Only one solid adorbent tube 

was lost to breakage. The “Refuel Can” in Table 2.4-1 refers to the 5-minute integrated 

canister collected during the actual refueling event. One canister could not be sampled 

because it was at atmospheric pressure when opened in the field, and the data obtained from

the other one were invalidated, thus leading to a 80% capture rate for this category. The

“Breath Can” refers to the breath canisters (2 or 3 per ME) which were all collected. For the 

continuous and semi-continuous methods, we had very good data capture with only one run 

missing for the Outside PID (the one measuring outside the vehicle cabin during the freeway 

ME). This was due to a software difference between this and our older instrument that 

resulted in the data logging function being accidentally turned off. The NDIR instrument lost 

some data due to insufficient power in a few early runs; fortunately the T-15 CO functioned 

perfectly for these runs. For the few runs where the T-15 CO data logging had problems, we 

have the NDIR data thus at least one instrument was functioning for CO during all MEs. The

MS200 worked very well during most of the early runs, but some detector sensitivity

problems and other undiagnosed problems resulted in complete loss of data for the last four 

runs. One freeway run had mostly good data with 5 minutes out of the 40 minute total being 

lost due to electrical noise of undetermined origin. This is a similar problem we had during 

the San Antonio study and may be related to the van’s electrical system since proximity to 

the other instruments in the refueling MEs did not cause similar noise. 

The formaldehyde instrument showed some good data but overall data capture rate was low,

mostly due to an electrical shortage in the thermocouple that controls the heated reaction cell. 

This problem was not identified and fixed until the afternoon of May 2, 2003. Without 

adequate control of the temperature of the heated reaction cell, there is little certainty that the 

formaldehyde collected was actually derivatized in a consistent manner. This malfunction 

was diagnosed and fixed prior to the parking garage sample ME2-4, and did not reoccur. 

Another major source of malfunction was the presence of air in the sample stream reaching

the detector. Although an in-line debubbler worked well for removing air bubbles from the 

sample stream, air may still have reached the detector if pump flow rates were not properly 

balanced among the 4 pumps and air was accidentally pumped into the detector. This 

occurred during the freeway (ME1-5) and refueling without vapor recovery (ME4-4) tests on 

May 5, 03. Another limitation of this continuous instrument was the long stabilization time

required for the fluorescence detector upon instrument start-up. In some cases, response at 

the detector was still stabilizing when the sampling period began. One of the most 

significant limitations of the formaldehyde monitor was an apparent sensitivity to moving 

environments. It has been observed that when the formaldehyde instrument was warmed up 

and operated in a stationary environment, such as a parking garage, and then subjected to 

transport while still operating, response at the detector oscillated and increased in overall. 

2-15
Figure 2.4-1 shows the response of the continuous formaldehyde analyzer, stabilized and 

“zeroed” with a DNPH cartridge at the inlet, when stationary and following startup and 

driving of the sampling van where the response of the detector increases and oscillates. (V) pon CHO

H

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

0.6

16:40:4816:48:0016:55:1217:02:2417:09:3617:16:4817:24:0017:31:1217:38:2417:45:3617:52:48

Time

 Res se

installed DNPH on inlet

at 17:22 and continued 

sampling in garage

Started van and drove back to 

DRI, DNPH still on inlet and

still acquiring

Figure 2.4-1. Effect of driving on continuous formaldehyde analyzer, during and after 

sampling in ME2-5. 

The environmental conditions (temperature, relative humidity, position, speed and other 

parameters) had one run where the logging system apparently locked up about 6 min into the 

run and gave no further data. This was a 20 min refueling run and does not represent a 

significant loss in data since the temperatures and humidity probably did not change 

appreciably. 

Table 2.4-1. Data Capture Summary 

Parameter Data Capture

Ambient Can 100%

Refuel Can 80%

Breath Can 100%

DNPH 100%

Solid Ads. 95%

SPME 100%

PID In (1) 100%

PID Out (2) 80%

NDIR CO 85%

T-15 CO 85%

MS200 70%

Formaldehyde 10%

Env. Cond. 95%

2-16
3. RESULTS 

The main goal of the 2nd Reno Pilot Study was to demonstrate proper operation and 

reliability of analytical instrumentation and comparability of time-integrated, semicontinuous and continuous methods for compounds of interest. The results section examines 

the consistency between redundant measurements and co-pollutants, evaluates temporal and 

spatial variations, and correlations among the various data sets for measured parameters that

we expect will be correlated. One key aspect of the study design was the built-in redundancy 

between the continuous methods and the time-integrated methods. For example, CO was 

measured from the time-integrated canister samples and from the T-15 and NDIR 

instruments. We measured BTEX from canisters, continuous MS-200 and semi- continuous 

SPME as well as a surrogate measure in the PID signal. Formaldehyde was measured by the 

continuous HCHO instrument and by the DNPH cartridges. In addition, we measured PID 

signal from two independent ppbRAE units positioned in-cabin and outside the cabin, or

collocated in outdoor microenvironments. 

3.1 Method Comparison of Redundant Data 

3.1.1 PID versus PID 

Two identical ppbRAE continuous PID monitors were used to estimate total VOC 

concentrations, ionizable at 10.6 eV, inside and outside the vehicle cabin. Prior to and after 

the pilot study, both units were calibrated using an activated carbon inlet filter for the zero 

point and a certified BTEX mixture (total concentration 3700 ppb) for span. 

During several tests, the second unit was collocated with its inlet within 10 cm of the inlet of 

the primary unit for quality assurance purposes. The resulting data is shown in Figure 3.1-

1a,b. While the two units track each other accurately, after adjusting for differences in inlet 

transit time, the absolute concentrations recorded differ significantly. The primary unit 

(PID1) demonstrated a positive offset of 40-50 ppb, which was expected since it would not 

read below ~40 ppb even when the carbon inlet filter was in place. This behavior is evident 

in the tests shown in Figure 3.1-1b. No consistent bias was observed at the high peak 

concentrations shown in Figure 3.1-1a, with both units reading higher at times. Since this 

time a difference in software was identified, and they have been harmonized for future 

studies. 

3-1
M E4 - Refueling w/o VR: test4

0

100 0

200 0

300 0

400 0

500 0

600 0

700 0

800 0

900 0

0 5 10 15

elaps ed time (m in)

BTEX estimated by PID (ppb)

P ID1 PID2

20

M E4 - Refueling w/o VR: test5

0

50 00

100 00

150 00

200 00

250 00

300 00

0 5 10 15 20

ela pse d tim e (m in)

BTEX estimated by PID (ppb)

PID 1 PID2

Figure 3.1-1a. Comparison of estimated BTEX concentrations measured by PID instruments 

with inlets collocated within 10 cm. Data are running 1 minute averages. VR = nozzle vapor 

recovery. 

3-2
M E3 - Refueling w/ VR: test5

0

5 0

10 0

15 0

20 0

25 0

0 5 10 15

e la pse d tim e (m in)

B

TEX estimated by PID (ppb)

PID1 PID2

20

M E2 - Parking Garage: test5

0

10

20

30

40

50

60

70

80

90

1 00

0 5 10 15

e la pse d tim e (m in)

B

TEX estimated by PID (ppb)

PID1 PID 2

20

Figure 3.1-1b – cont’d. Comparison of estimated BTEX concentrations measured by PID 

instruments with inlets collocated within 10 cm. Data are running 1 minute averages. VR = 

nozzle vapor recovery.

3-3
Figure 3.1-2 shows the corresponding total VOC concentrations, ionizable at 10.6 eV, 

recorded by the two ppbRAE monitors during four freeway driving tests (data for the 

ambient unit during test 2 was lost due to a data logger configuration error) where the second 

unit measured ambient VOC concentrations outside the vehicle. As in the collocated unit 

tests, the two monitors track each other well during the high ventilation segment of the test 

(first 20 minutes). The less dynamic variations in concentration recorded by the in-cabin unit 

are consistent with expectations. 

After the switch to low ventilation conditions at 20 minutes elapsed time, the in-cabin unit 

shows very little correlation to the ambient unit and, while not always stable, shows no 

accumulating drift evidence of interior sources or interferences. 

3-4
ME1 - Freeway: test3

0

100

200

300

400

500

600

700

800

900

0 5 10 1 5 20 2 5 30 35 40

e la psed time (min)

BTEX estim ated by PID (ppb)

in-cabin PID ambient PID

ME1 - Freeway: test1

0

200

400

600

800

1000

1200

0 5 10 15 2 0 25 30 35 40

elaps ed tim e (m in)

BTEX estim ated by PID (ppb)

in-cabin PID ambient PID

Figure 3.1-2. Comparison of estimated BTEX concentrations measured by PID instruments 

during freeway driving tests. Data are running 1 minute averages. 

3-5
ME1 - Freeway: test4

0

100

200

300

400

500

600

700

0 5 10 1 5 20 25 30 35 40

elapse d tim e (min)

BTEX estim ated by PID (ppb)

in-cabin PID ambient PID

ME1 - Freeway: test5

0

100

200

300

400

500

600

0 5 10 15 20 25 30 35 40

elaps ed time (min)

BTEX esti

m ated by PID (ppb)

in-cabin PID ambient PID

Figure 3.1-2 –cont’d. Comparison of estimated BTEX concentrations measured by PID 

instruments during freeway driving tests. Data are running 1 minute averages. 

3-6
3.1.2 NDIR vs. Electrochemical CO 

Both an EPA-certified gas-filter correlation NDIR optical CO analyzer (API model 300) and 

a portable battery-operated passive electrochemical cell instrument (Langan T-15) were 

operated during all tests to measure CO. Although data recovery was less than 100% for each 

method, and the electrochemical instrument was not equipped to sample outside the in-cabin 

breathing zone during the refueling and garage tests, collocated measurements were collected

during the two tests shown in Figure 3.1-3. 

Although the NDIR instrument recorded higher peak values, due to its faster reponse time,

the measurements are generally consistent to within about 1 ppm. During the low-ventilation, 

half of the tests shown the CO concentrations remain at or decrease towards the lowest level 

measured during the high-vent phase. This behavior suggests that no in-cabin sources or

interferences are present. 

There was good agreement between the two types of CO analyzers, due to the NDIR 

instrument’s internal adaptive filtering. This filter, which is required for EPA certification, is

intended to adjust the response rate of the instrument with respect to the stability of the raw 

detector signal during a preceding time period, to reduce noise. The length of the ‘filtering’

period can range from 10 seconds up to 2 minutes, according to the manufacturer. In practice,

the adaptive filter effectively averages the output data over a variable time period, resulting 

in concentration fluctuations that are broader and have a peak that occurs later in time and a 

lower maximum height. This effect can be seen in Figure 3.1-4, which shows the measured 

CO concentrations from two similar instruments drawing air from the same inlet inside the 

cabin of the test van while driving on freeway and surface streets with windows open (this 

test was performed later in the day than the ME1 tests, concentrations are lower). The

API300 was the same instrument used in the pilot study, while the ML9830 (Monitor Labs) 

was an equivalent EPA-certified gas-filter correlation NDIR instrument that was operated 

with the adaptive filter turned off (a fixed 10 second filtering period was selected). Both 

instruments have the same performance specifications and were calibrated just prior to the

test using zero air and a 10.0 ppm CO standard, yet the ML9830 time series is much more

dynamic and shows higher peak concentrations. Figure 3.1-4 also shows a time series of the 

ML9830 data in which the four minutes preceding each data point were averaged. This series 

matches the API300 data almost exactly, except for the first large peak which was apparently 

steep enough to trigger the API300’s adaptive filter into fast response mode. 

Despite the differences in response rate, the overall average concentrations recorded for the 

test period shown were very comparable: 1.26 ppm from the ML9830 versus 1.31 ppm from 

the API300. Fast response is desired in order to better characterize the variability of pollutant

concentrations in a microenvironment, so the ML9830 is preferable for the field study. In 

addition to the convenience of front panel configuration of the data filter, the ML9830 also

uses about 50% less power and has an internal zero air generator to allow automatic baseline 

checks. 

3-7
ME1 - Freeway: test3

0

5

10

15

20

25

30

35

40

45

50

0 5 10 15 20 25 30 35 40

elapsed tim e (m in)

C

O (ppm)

ND IR_CO Langan_CO

ME1 - Freeway: test4

0

2

4

6

8

10

12

14

0 5 10 15 20 25 30 35 40

elapsed tim e (m in)

CO (ppm)

NDIR_CO Langan_CO

Figure 3.1-3. Comparison of NDIR (API model 300) and electrochemical (Langan T15v) 

CO monitors during two freeway driving tests. 

The NDIR CO data are running 1 minute averages, while the electrochemical instrument 

recorded data is in discrete 1 minute averages. In test 3, the NDIR instrument’s analog output 

range (0-20 ppm) was exceeded during the first 4 minutes. 

3-8
0

2468

1012

15:40

15:45

15:50

15:55

16:00

16:05

16:10

CO (ppm)

ML9830 API300 ML9830_4min.Avg

Figure 3.1-4. Comparison of two gas-filter correlation NDIR CO analyzers during on-road sampling. Data from the ML9830 instrument are shown as recorded (10 second averages) and as 4 minute running averages

3-9
3.1.3 CO versus Canister CO 

Average CO concentrations were also measured by GC analysis of the integrated canister

samples that were collected for the duration of each test. Figure 3.1-5 shows a scatter plot of 

the average continuous data from the NDIR or electrochemical CO instruments versus the 

CO from the corresponding canister. The canister CO is generally about 8% higher, but there 

is no consistent bias. The comparison is also made on a test-by-test basis in the second chart 

of this figure, showing that discrepancies between the two methods occur in all 

microenvironments and at both high and low concentrations. The underestimation of CO by 

the NDIR instrument in the two tests with the highest average concentration (ME1- test 3 and 

ME2 – test 2) is due, at least in part, to exceedences of the instruments output range which 

resulted in truncation of peak concentrations above about 23 ppm. This over-ranging problem 

was identified and corrected before the end of the pilot study. 

3-10
y = 1.08x

R2 = 0.85

0

2

4

6

8

10

12

0 246 8 10 12

average of continuous CO

C

a

nister C

O

0

2

4

6

8

10

12

ME1 ME2 ME3 ME4

CO (

p

p

m)

average of continuous CO

Canister CO

Figure 3.1-5. Average CO concentration for each test measured by continuous monitor and

GC analysis of integrated canister sample. ME1= morning rush hour commute; 

ME2=parking garage; ME3= refueling with vapor recovery; ME4= refueling without vapor 

recovery. 

3-11
3.1.4 MS vs. Canister 

The MS200 performed well in 16 of the 20 ME tests. For all of those runs we can compare 

the integrated MS200 response to the canister data. Figure 3.1-6 shows the correlation for

benzene, toluene and the sum of the C8 benzenes (ethylbenzene, o, m, & p-xylene). The C8 

benzenes are presented together because we cannot separate them using the MS200. The 

correlations are all very good, with > 0.9 R-square. The correlation for toluene is the best 

with a 0.99 R-square. Both toluene and the C8 benzenes show a close 1:1 correlation, but 

benzene seems to be overpredicted by the MS200. 

Bz = 1.1537x + 1.0948

R2

 = 0.9016

Tol = 0.9703x + 1.8068

R2

 = 0.9914

C8 = 1.0638x + 0.6664

R2

 = 0.9529

0

10

20

30

40

50

60

70

80

0 20 40 60 80

Canister, ppbv

MS200, ppbv

Benzene

Toluene

C8 Benzenes

Linear (Benzene)

Linear (Toluene)

Linear (C8 Benzenes)

Figure 3.1-6 Comparison of canister and MS200 data for all measured species. 

To further investigate the comparison for benzene, we plotted the benzene concentrations in 

Figure 3.1-7. This figure shows random scatter around the trend line over the range of 25 

ppbv down to less than 2 ppbv. Overall the MS200 performed very well for runs with valid 

data. We are still investigating the causes of the failures of this instrument and feel that it 

provides excellent supplemental data but should not be relied upon as a primary method. 

3-12
Bz = 1.1537x + 1.0948

R2

 = 0.9016

0

5

10

15

20

25

30

0 5 10 15 20 25 30

Canister, ppbv

MS200, ppbv

Benzene

Linear (Benzene)

Figure 3.1-7. Comparison of MS200 and canister for benzene only. 

3.1.5 SPME vs. Canisters 

Table 3.1-1 shows the comparison of canister BTEX data with averaged and temperature 

corrected SPME data. In general, SPME BTEX concentrations are higher than canister 

concentrations. This is most probably due to the temperature differences between the static 

calibration and sampling conditions and inadequate correction for temperature. However, the 

passive SPME sampling rate could also be affected by the local wind speed, especially if the 

local gusts are close to 5 mph threshold. We observed higher SPME uptake of analytes in the 

dynamic system, if the flow rate of a standard gas mixture was higher than 100 ml/min. 

After cleaning and conditioning, the SPME fibers were stored in the freezer and taken to 

sampling sites in a cooler with dry ice. Although the fibers were taken out of the cooler prior 

to sampling, we are not certain if sufficient time was allowed for fiber equilibrations to

ambient temperature. In retrospect, it was an error, since we determined later that the fiber 

uptake is highly dependent on temperature (see Section 2.3.2). For the primary study we will 

change the SPME fiber storage conditions and will store them in metal cans with activated 

charcoal at the bottom (similar to Tenax tubes) at ambient temperature. 

3-13
Table 3.1-1. Data comparison between SPME and Canister 

can spme can spme can spme can sp

site date strthhmm benze benze tolue tolue etbz etbz mp_xyl mFreeway 4/29/03742-822 9.10 15.03 45.35 87.42 7.48 18.37 24.92 5Refueling W/Vapor Recovery 4/29/031200-1220 3.38 11.94 9.91 52.85 1.43 10.70 4.82 2Garage 4/29/031642-1712 5.65 19.00 14.67 56.49 3.10 16.11 10.52 4Freeway 4/30/03739-819 10.01 24.01 53.75 127.78 8.69 25.11 29.48 7Refueling W/O Vapor Recovery 4/30/03921-941 9.46 29.04 34.27 112.88 5.50 18.02 19.02 6Refueling W/Vapor Recovery 4/30/031045-1105 1.30 4.66 4.53 20.46 0.97 6.93 3.50 1Refueling W/O Vapor Recovery 4/30/031205-1245 2.13 11.02 7.85 51.68 1.15 14.11 3.96 3Garage 4/30/031645-1715 9.94 37.25 31.92 110.84 6.98 26.43 24.06 8Freeway 5/1/03720-800 18.13 32.60 75.57 146.83 12.28 26.77 40.13 8Refueling W/O Vapor Recovery 5/1/031106-1126 2.34 6.80 10.10 49.24 1.83 14.57 6.48 3Refueling W/Vapor Recovery 5/1/031225-1245 1.61 5.61 6.28 17.02 1.20 4.60 4.21 1Garage 5/1/031642-1717 10.63 20.33 34.25 71.17 7.23 13.91 25.35 4Freeway 5/2/03735-815 7.27 22.62 30.81 114.78 4.77 24.76 15.66 6Refueling W/O Vapor Recovery 5/2/03918-938 20.49 44.77 59.93 154.25 8.13 31.25 28.70 9Refueling W/Vapor Recovery 5/2/031036-1056 2.30 20.44 9.28 67.20 2.10 12.17 7.83 4Garage 5/2/031645-1715 5.29 6.07 17.10 22.80 3.79 5.55 13.53 1Freeway 5/5/03750-830 9.60 19.25 44.69 108.01 8.31 18.21 28.76 6Refueling W/O Vapor Recovery 5/5/03923-943 66.93 52.76 142.14 198.26 11.17 18.30 36.03 6Refueling W/Vapor Recovery 5/5/031045-1105 1.55 5.75 7.23 18.13 1.39 2.49 4.96 9Garage 5/6/031645-1715 4.86 6.29 14.16 22.39 3.25 5.82 11.75 2

3-14
Figure 3.1-8 shows the scatter plots for canister and SPME data before temperature 

corrections. 

0

50

100

150

200

250

0 50 100 150 200 250

Canister Concentration (ppb)

S

P

ME Concentration (ppb) benzene toluene ethylbenzene m,p-xylene o-xylene

Figure 3.1-8. Scatter Plots for raw data from SPME vs canister for the Pilot Study 2003 

Scatter plots after temperature correction. 

0

50

100

150

200

0 50 100 150 200

Canister Con centratio n (p pb)

SPME Con centration (pp b) benzene toluene ethylbenzene m,p-xylene o-x ylene

Figure 3.1-9. Scatter Plots for temperature corrected SPME vs canister data for the Pilot 

Study 2003 

Figure 3.1-10 and Table 3.1-2 shows the correlations after removing the two visible outliers 

(benzene and toluene from refueling w/o vapor recovery May 5th at 923-943): 

3-15
0

40

80

120

160

0 40 80 120 160

Canister Con centratio n (p pb)

SPME Con centration (pp b) benzene toluene ethylbenzene m,p-xylene o-x ylene

Figure 3.1-10. Scatter plots from SPME vs Canister for the Pilot Study 2003 with two 

outliers removed. 

Table 3.1-2. Correlation of Scatter Plots from SPME and Canister Comparison 

Compound Equation Correlation

Benzene y = 1.8365x + 4.9732 R2

 = 0.7291

Toluene y = 1.9202x + 22.617 R2

 = 0.7936

Ethylbenzene y = 1.6894x + 7.1997 R2

 = 0.5255

m,p-xylene y = 1.7814x + 17.323 R2

 = 0.6452

o-xylene y = 1.6367x + 4.0433 R2

 = 0.6526

The scatter plots show linearity of the SPME data compared to canister data but the relatively 

low correlation values and the slope in the range of 1.6 – 1.9 can be associated with the 

differences in storage of the conditioned fibers before sampling. As noted above, most fibers 

were not probably stabilized to ambient temperature before sampling. Since the fibers were

colder than the environment, some variability of the data is expected. This problem will be 

corrected in the primary study. 

Sampled fibers were stored an average of 5 hours and all samples were analyzed the same

sampling day. 

3-16
3.1.6 SPME vs. MS 

Data from SPME semi-continuous samples compared satisfactorily with continuous data 

obtained from the MS 200. In general concentrations are within the same ranges and changes 

in concentration levels track each other most of the time. However, the SPME concentrations

are higher in most cases. As explained before, this may be due to the inadequate correction

for temperature and humidity differences as compared with static calibration conditions and 

cold fiber storage conditions prior to sampling. 

3-17
Ethylbenzene and xylenes

0

40

80

120

160

7:30:43 7:37:55 7:45:07 7:52:19 7:59:31 8:06:43 8:13:55 8:21:07

Time

Concentration, ppb

MS SPME

Benzene

0

10

20

30

7:30:43 7:37:55 7:45:07 7:52:19 7:59:31 8:06:43 8:13:55 8:21:07

Time

Concentration, ppb

MS SPME

Toluene

0

40

80

120

160

7:30:43 7:37:55 7:45:07 7:52:19 7:59:31 8:06:43 8:13:55 8:21:07

Time

Concentration, ppb

MS SPME

Figure 3.1-11. 10 minutes average MS data vs SPME benzene and toluene concentrations: 

Freeway 5/02 7:35-8:15 am

3-18
Benzene

0

10

20

30

40

7:33:36 7:40:48 7:48:00 7:55:12 8:02:24 8:09:36 8:16:48 8:24:00

Time

Concentration, ppb

MS SPME

Toluene

40

80

120

160

7:33:36 7:40:48 7:48:00 7:55:12 8:02:24 8:09:36 8:16:48 8:24:00

Time

Concentration, ppb

MS SPME

Ethylbenzene and xylenes

0

40

80

120

160

7:33:36 7:40:48 7:48:00 7:55:12 8:02:24 8:09:36 8:16:48 8:24:00

Time

Concentration, ppb

MS SPME

Figure 3.1-12. 10 minutes average MS data vs SPME benzene and toluene concentrations: 

Freeway 4/30, 7:35 am

3-19
benzene

0

30

60

90

9:15:50 9:18:43 9:21:36 9:24:29 9:27:22 9:30:14 9:33:07 9:36:00 9:38:53

Time

Concentration, ppb

MS SPME

Toluene

0

50

100

150

200

250

300

9:15:50 9:18:43 9:21:36 9:24:29 9:27:22 9:30:14 9:33:07 9:36:00 9:38:53

Time

Concentration, ppb

MS SPME

Ethylbenzene and xylenes

0

50

100

150

200

250

300

9:15:50 9:18:43 9:21:36 9:24:29 9:27:22 9:30:14 9:33:07 9:36:00 9:38:53

Time

Concentration, ppb

MS SPME

Figure 3.1-13. 10 minutes average MS data vs SPME benzene and toluene concentrations: 

Refueling w/o VR 5/02 9:18 am

3-20
3.1.7 DNPH vs. Formaldehyde 

Comparisons of formaldehyde data are few since the supplemental continuous analyzer 

provided little reliable data due to flow fluxuation and unstability during movement

Comparison of formaldehyde data from DNPH with the final garage sampling event (ME2-5) 

shows that average concentration of formaldehyde detected by the continuous instrument was

11.5 ppb, and the time integrated DNPH sample for the same event was only 5.41 ppb. If

data from the continuous CO monitor from the same experiment is used to reconstruct 

concentrations of formaldehyde for the earlier portions of the run, the average formaldehyde 

concentration may be estimated and compared to the DNPH time-integrated formaldehyde 

data (described in 3.2.2.). 

The continuous formaldehyde detector is designed for stationary laboratory use, which 

accounts for its poor performance on a mobile platform. Based on these pilot study results, 

continuous formaldehyde measurements will only be made for stationary measurements in 

the 3 city field studies. 

3.1.8 Tenax vs. Canisters 

Appendix B list the full data sets for canister and Tenax samples. Since Tenax and canister

samples overlap at C8-C12 carbon numbers, it is possible to compare concentrations for 

toluene, ethylbenzene, m/p-xylene and o-xylene obtained from both methods. Figure 3.1-14 

shows that the correlations between both methods are good. The scatterplots exclude the 

5/5/03 refueling without vapor recovery (ME4) samples. For this one ME4 replicate, the 

canister value was much higher than the Tenax sample, suggestive of a Tenax tube 

breakthrough. for this ME. This could be due to the extremely high gasoline concentrations

encountered in this ME. It is possible that the breakthrough occurred for Tenax sample. One 

issue with the Tenax samples is the accurate determination of the volume sampled. Since the

flow rate is measured at the beginning and at the end of all sampling periods, and the average 

flow is used for volume calculation, it is possible that the volume is not very precise, if the 

flow drop over the sampling period is substantial and non-linear. We are currently improving 

on the standard method by adding the data logger to the canister-Tenax-DNPH cartridge

sampling system that will allow us to continuously monitor flow rates, thus allowing for 

accurate volume determination. 

3-21
Toluene

y = 0.8853x + 8.4119

R2

 = 0.8595

0

50

100

150

200

250

300

350

400

450

0 50 100 150 200 250 300 350 400 450

Cans, ppbC

Tenax, ppbC

Ethylbenzene

y = 0.9935x - 3.7545

R2

 = 0.9089

0

10

20

30

40

50

60

70

80

90

0 10 20 30 40 50 60 70 80

Cans, ppbC

Tenax, ppbC

m/p-Xylene

y = 1.1225x - 11.694

R2

 = 0.9236

0

50

100

150

200

250

300

350

0 50 100 150 200 250

Cans, ppbC

Tenax, ppbC

o-Xylene

y = 1.0321x - 6.038

R2

 = 0.9258

0

20

40

60

80

100

120

0 20 40 60 80 1

Cans, ppbC

Tenax, ppbC

00

Figure 3.1-14 Comparison of canister and Tenax data for all ME 

3-22
3.2 Comparisons of Correlated Data 

3.2.1 PID vs. CO 

Since both carbon monoxide and BTEX are produced by gasoline combustion, they are 

expected to track each other in an automobile exhaust dominated environments. Figure 3.2-1 

shows the two measurements track well during the parking garage tests that are focused on 

cold-start emissions, although the ratio is variable as indicated by the scatter in Figure 3.2-3. 

The apparent time lag for the smaller peaks is an artifact of the API NDIR CO instrument’s 

adaptive filtering, described in the previous section, and subsequent averaging of the data. 

During the freeway driving tests, shown in Figure 3.2-4, the correlation between CO and 

VOC is good, but not as high as the parking garage data. 

3-23
ME2 - Parking Garage: test1

0

2

4

6

8

10

12

14

16

18

0 5 10 15 2 0 25 30

e laps e d tim e (m in)

CO (pp

m)

0

5 0

1 00

1 50

2 00

2 50

3 00

3 50

4 00

BTEX estimated by PID (ppb)

NDIR_CO PID1

ME2 - Parking Garage: test2

0

5

10

15

20

25

30

0 5 10 15 20 25 30

e lapsed tim e (m in)

CO (ppm)

0

100

200

300

400

500

600

BTEX estimated by PID (ppb)

NDIR_CO PID1

Figure 3.2-1. Comparison of CO and BTEX by PID during parking garage tests. 

Data are running 1 minute averages. The CO instrument’s analog output range (0-20 ppm)

was exceeded briefly during the two large peaks near the end of test 2. 

3-24
ME2 - Parking G ar age: test3

0

5

10

15

20

25

0 5 10 15 20 2 5 30

e laps e d tim e (m in)

CO (pp

m)

0

1 00

2 00

3 00

4 00

5 00

6 00

BTEX estimated by PID (ppb)

ND IR_CO P ID 1

ME2 - Parking G ar age: test4

0

2

4

6

8

10

12

14

16

0 5 10 15 20 2 5 30

e laps e d tim e (m in)

CO (ppm)

0

5 0

1 00

1 50

2 00

2 50

3 00

3 50

BTEX estimated by PID (ppb)

NDIR_C O P ID 1

ME2 - Parking Garage: test5

0

5

1 0

1 5

2 0

2 5

0 5 10 1 5 2 0 25 30

e laps e d tim e (m in)

CO (ppm)

0

100

200

300

400

500

600

BTEX estimated by PID (ppb)

ND IR_CO PID 1

Figure 3.2-1 – cont’d. Comparison of CO and BTEX by PID during parking garage tests.

Data are running 1 minute averages. 

3-25
p arking garage tes ts

y = 17.48x + 13.46

R2 = 0.76

0

100

200

300

400

500

600

0 5 10 15 20 25 30

CO (ppm )

BTEX by PID (ppb)

Figure 3.2-3. Scatter plot of CO vs BTEX by PID during parking garage tests. Data are 

running 1 minute averages. 

3-26
ME1 - Freeway: test3

0

5

10

15

20

25

30

0 5 10 1 5 20 2 5 30 35 40

e lap sed tim e (m in)

CO (ppm)

0

1 00

2 00

3 00

4 00

5 00

6 00

7 00

8 00

9 00

BTEX estimated by PID (ppb)

ND IR_CO PID 1

ME1 - Freeway: test4

0

2

4

6

8

10

12

14

0 5 10 1 5 20 2 5 30 35 40

e lap sed tim e (m in)

CO (ppm)

0

1 00

2 00

3 00

4 00

5 00

6 00

7 00

BTEX estimated by PID (ppb)

ND IR_CO P ID 1

ME1 - Freeway: test5

0

1

2

3

4

5

6

7

8

9

10

0 5 10 1 5 20 2 5 30 35 40

e lap sed tim e (m in)

CO (ppm)

0

1 00

2 00

3 00

4 00

5 00

6 00

BTEX estimated by PID (ppb)

ND IR_CO PID 1

Figure 3.2-4. Comparison of CO and BTEX by PID during freeway driving tests. 

Data are running 1 minute averages. In test 3, the CO instrument’s analog output range (0-20 

ppm) was exceeded during the first 4 minutes. 

3-27
3.2.2 CO vs. Formaldehyde 

For the last two garage sampling events (ME2-4 and ME2-5), time series for continuous 

formaldehyde and CO show inconclusive results. Figure 3.2-5 shows time series data for CO 

and formaldehyde for ME2-4. During the ME2-4 period in which formaldehyde data was 

above the detection limit, both the CO and formaldehyde appear to respond to the same

event, but the peaks are not in phase with each other. 

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

16.00

18.00

20.00

16:40:4816:48:0016:55:1217:02:2417:09:3617:16:48

Time

HCHO (ppb)

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

16.00

18.00

20.00

NDIR CO (ppm)

HCHO (ppb)

NDIRCO (ppm)

Figure 3.2-5 ME2-4 continuous HCHO and CO time series with unexplained difference in 

lag between the two instruments. 

Approximately 2.5 minutes separate the instrument responses. This indicates that either the 

time lag correction of 6 minutes is not accurate for this test, or the adaptive smoothing 

feature of the CO instrument is causing a delayed peak rise in CO. Figure 3.2-6 shows the 

same time series data following adjustment of the formaldehyde data by 2.5 minutes to

compensate for the undetermined source of error. The data track each other very well. 

3-28
0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

16.00

18.00

20.00

16:40:4816:48:0016:55:1217:02:2417:09:3617:16:48

Time

HCHO (ppb)

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

16.00

18.00

20.00

NDIR CO (ppm)

HCHO (ppb)

NDIRCO (ppm)

Figure 3.2-6. ME2-4 continuous HCHO time series shifted back 2.5 minutes to match CO 

time series. 

Once this time adjustment was made, CO and HCHO concentrations were compared by 

regression, and the resulting equation ([HCHO] = [CO]*1.2996-1.14587, R2

 = 0.91) was 

used to estimate HCHO concentrations for the period prior to successful data capture for this 

experiment. The resulting average concentration for the estimated formaldehyde data 

combined with the actual formaldehyde data was 5.414 ppb. The time integrated 

formaldehyde data from the DNPH for the ME2-4 experiment was 7.348 ppb. The estimated 

value is 74% of the observed time integrated sample. Despite the discrepancy in phase 

between the continuous CO and formaldehyde analyzers, this experiment is the best 

indication that the continuous formaldehyde analyzer may work well if properly tuned and 

operated in a suitable environment. It also indicates that CO may serve as a useful surrogate 

for formaldehyde. To explore this relationship further, formaldehyde results from the DNPH 

cartridges were plotted in a scatter plot against CO from time integrated canister samples for 

each microenvironment. Figure 3.2-7 shows the plot with different microenvironments 

having unique symbols on the plot. Formaldehyde from the Freeway microenvironment does

not correlate with CO samples from the same environment. The garage and refueling 

microenvironments appear to have a positive correlation with CO but cluster for each

microenvironment. Fitting a linear regression through data points for the Garage and 

Refueling microenvironments, neglecting the Freeway microenvironment, gives a good 

correlation ([HCHO] = 0.594*[CO] + 0.397, R2

 = 0.793). 

3-29
0

5

10

15

20

25

0 2 4 6 8 10 12 14

Can CO (ppm)

DNPH HCHO (ppb)

Garage

Freeway

Refuel w/o V.R.

Refuel w/ V.R.

Figure 3.2-7. Scatter plot of formaldehyde (from DNPH) and CO for all microenvironments. 

3-30
Finally, comparison of continuous formaldehyde and CO measurements for the last garage 

sampling event (ME2-5) shows poor correlation in phase and timing (Figure 3.2-8). The

unexplained 2.5 minute lag that resolved peaks in the ME2-4, did little to help this

comparison. 

0.00

5.00

10.00

15.00

20.00

25.00

16:4016:4816:5517:0217:0917:16

Time

HCHO (ppb)

0.00

5.00

10.00

15.00

20.00

25.00

NDIR CO (ppm)

HCHO (ppb)

NDIR CO (ppm)

Figure 3.2-8. Formaldehyde and CO time series for ME2-5. 

3-31
3.2.3 SPME vs. PID 

SPME total BTEX semi-continuous data compares reasonably with the continuous signal 

obtained from the interior PID situated right next to the fiber while sampling. The SPME 

concentrations are within the range of the PID signal and follow the changes in PID 

concentrations. 

100

200

300

400

7:35 7:41 7:48 7:55 8:01 8:08 8:15

Time

PID Concentration (ppbv)

100

200

300

400

SPME Concentration 

(ppbv)

PID1 SPME tot BTEX

Figure 3.2-9. SPME 10 min total BTEX vs. PID 10 min averages, Freeway, 5/02, 7:35 am

0

100

200

300

400

500

600

700

9:21 9:27 9:34 9:41

Time

PID C

onc

e

ntration (

ppbv)

0

100

200

300

400

500

600

700

S

P

M

E C

onc

e

ntration (

ppb

v)

PID1 SPME tot BTEX

Figure 3.2-10. SPME 10 min total BTEX vs. PID 10 min averages, Refueling w/o VR 4/30 

9:21am.

3-32
0

100

200

300

400

500

600

700

7:39 7:45 7:52 7:59 8:05

Time

PID C

oncentration (ppbv)

0

100

200

300

400

500

600

700

SPM

E C

o

n

c

e

ntratio

n

(p

p

bv)

PID1 SPME tot BTEX

Figure 3.2-11. SPME 10 min total BTEX vs. PID 10 min averages, Freeway 4/30, 7:35 am. 

0

2 0 0

4 0 0

6 0 0

8 0 0

100 0

120 0

140 0

160 0

180 0

9 : 1 8 9 :2 4 9 : 3 1 9 :3 8

T im e

PID Concentration (ppbv)

0

2 0 0

4 0 0

6 0 0

8 0 0

1 000

1 200

1 400

1 600

1 800

SPME Concentration (ppbv)

P ID 1 S P M E to t B TE X

Figure 3.2-12. SPME 10 min total BTEX vs. PID 10 min averages, Refueling w/o VR 5/02 

9:18 am. 

3-33
0

50

100

150

200

16:45 16:51 16:58 17:05 17:11

Time

PID Concentration (ppbv)

0

50

100

150

200

S

PME C

oncentration (ppbv)

PID1 SPME tot BTEX

Figure 3.2-13. SPME 10 min total BTEX vs. PID 10 min averages, Parking Garage 5/06, 

16:45 pm. 

Continuous estimates of total VOC by a PID ppbRAE monitor compared reasonably to the 

semi-continuous measurements of BTEX obtained from analysis of SPME fibers. 

3-34
3.3 Environmental Factors 

The various environmental conditions monitored during this study are presented in this 

section by microenvironment. These data were collected once every 10 seconds, to simplify 

the presentation, we present the average for each 10 min segment (to correspond with the 

SPME time interval) and the overall average value In addition, we present temperature and 

wind data collected at a weather station on top of DRI’s building. These data are useful as a 

general reference for local conditions, however, it is important to point out that DRI’s 

building is on top of a hill with nothing to block winds for approximately 270 degrees around

and is noted as being one of the windiest spots in the area. This is important since we

selected the refueling stations in a location at the bottom of a nearby valley approximately 

250 feet lower in elevation with a large ridge blocking the prevailing winds. For all stationary 

MEs we monitored wind with a hand-held anemometer that had a lower-limit of detection of

approximately 1 mph. 

For the freeway microenvironment (ME1), we measured temperature and relative humidity at 

the driver’s breathing zone which was also the sample inlet location for all equipment except 

the second PID which was monitoring the air outside the van. The outside PID inlet was 

located on the radio antenna on the right front corner of the van. Since the sampling location 

was inside the van, the temperature is typically higher than the ambient. We also monitored

the temperature on the outside surface of the fuel tank. These data are presented in Table 3.3-

1 along with the average conditions for the DRI weather station. The average temperature in 

the van climbed during the runs partially due to the fact that we started low ventilation 

conditions halfway through the run. Relative humidities were relatively constant. The fuel 

tank temperature climbed steadily during the run, which was interesting considering the 

ambient temperatures did not. This was due to the recirculation of fuel after is passes the fuel 

injectors and picks up heat from the engine. The 10 second data of fuel tank temperatures for 

an example run are presented in Figure 3.3-1. 

3-35
Table 3.3-1. Environmental Conditions for Freeway Driving MEs. 

Fuel Tank

ME Date Start End Data Set Temp, C Humidity, % Temp, C Wind, mph Temp, C

ME1 - Freeway 4/2904/29/03 7:42 8:22 avg. of 1st 10 minutes: 12 37 5

avg. of 2nd10 minutes: 12 32 7

avg. of 3rd 10 minutes: 16 32 11

avg. of 4th 10 minutes: 21 32 13

Average of all 15 33 9 1.8 4.4

ME1 - Freeway 4/3004/30/03 7:39 8:19 avg. of 1st 10 minutes: 10 42 4

avg. of 2nd10 minutes: 13 34 7

avg. of 3rd 10 minutes: 21 28 11

avg. of 4th 10 minutes: 25 26 14

Average of all 17 33 9 3.0 1.5

ME1 - Freeway 5/0105/01/03 7:20 8:00 avg. of 1st 10 minutes: 11 44 7

avg. of 2nd10 minutes: 16 31 8

avg. of 3rd 10 minutes: 20 30 10

avg. of 4th 10 minutes: 21 34 12

Average of all 17 35 9 1.2 4.4

ME1 - Freeway 5/0205/02/03 7:35 8:15 avg. of 1st 10 minutes: 16 36 11

avg. of 2nd10 minutes: 20 30 12

avg. of 3rd 10 minutes: 23 30 15

avg. of 4th 10 minutes: 23 33 16

Average of all 20 32 14 4.5 7.8

ME1 - Freeway 5/0505/05/03 7:50 8:30 avg. of 1st 10 minutes: 15 39 7

avg. of 2nd10 minutes: 17 33 9

avg. of 3rd 10 minutes: 20 36 12

avg. of 4th 10 minutes: 22 39 16

Average of all 18 37 11 1.8 5.4

Sampling Point Measures

Ambient Conditions

(DRI Weather Station)

3-36
0

2

4

6

8

10

12

14

16

18

7:33 7:40 7:48 7:55 8:02 8:09 8:16 8:24 8:31 8:38

Time

Fuel T

ank 

T

e

m

p, C

Start Motor

Start Sampling

End Sampling

Figure 3.3-1. Fuel tank temperatures during freeway ME on 4/29/03. Ambient temperature 

was 4.4 C during this time. 

For the garage microenvironment (ME2) we measured temperature and relative humidity at 

the sampling point, which was also the sample inlet location for all equipment located on the 

tripod near the van. These data are presented in Table 3.3-2 along with the average 

conditions for the DRI weather station. The average temperature and relative humidities were 

relatively constant, as was the fuel tank temperature as might be expected for this stationary 

and mostly indoor ME. While the average winds at DRI were quite high (twice in excess of

10 mph) inside the garage the winds were calm and undetectable by the hand-held 

anemometer. The above-ground garage is also approximately 3.5 miles south and slightly 

west of the DRI building (measured in a straight line). 

3-37
Table 3.3-2. Environmental Conditions for Garage MEs. 

Fuel Tank Local

ME Date Start End Data Set Temp, C Humidity, % Temp, C Wind, mph Temp, C Winds

ME2 - Parking Garage 4/29 04/29/03 16:42 17:12 avg. of 1st 10 minutes: 11 35 15

avg. of 2nd10 minutes: 10 35 15

avg. of 3rd 10 minutes: 10 36 15

Average of all 10 35 15 8.3 9 Calm, not measureabl

ME2 - Parking Garage 4/30 04/30/03 16:45 17:15 avg. of 1st 10 minutes: 12 33 14

avg. of 2nd10 minutes: 11 33 14

avg. of 3rd 10 minutes: 11 33 14

Average of all 11 33 14 10.4 10 Calm, not measureabl

ME2 - Parking Garage 5/01 05/01/03 16:42 17:17 avg. of 1st 10 minutes: 16 24 16

avg. of 2nd10 minutes: 14 25 16

avg. of 3rd 10 minutes: 14 26 16

Average of all 15 26 16 4.9 14 Calm, not measureabl

ME2 - Parking Garage 5/02 05/02/03 16:45 17:15 avg. of 1st 10 minutes: 14 46 15

avg. of 2nd10 minutes: 14 48 15

avg. of 3rd 10 minutes: 14 47 15

Average of all 14 47 15 4.5 12 Calm, not measureabl

ME2 - Parking Garage 5/06 05/06/03 16:45 17:15 avg. of 1st 10 minutes: 14 34 16

avg. of 2nd10 minutes: 13 34 16

avg. of 3rd 10 minutes: 14 35 15

Average of all 14 34 16 11.7 11 Calm, not measureabl

Sampling Point Measures

Ambient Conditions

(DRI Weather Station)

For the refueling microenvironments (ME3 was with vapor recovery, ME4 was without 

vapor recovery), we measured temperature and relative humidity at the sampling point which 

was also the sample inlet location for all equipment. This was located on the tripod between

the van and the fuel pump to allow us to assess the conditions at the breathing zone of the 

person refueling the van. These data are presented in Table 3.3-3 along with the average 

conditions for the DRI weather station. The average temperature and relative humidities were 

relatively constant, as was the fuel tank temperature as might be expected for this 20 minute 

stationary ME. While the average winds at DRI did go above the 5 mph threshold for three of 

the MEs, the winds at the refueling stations were much lower as monitored by the hand-held 

anemometer. The stations are 1.3 and 1.9 miles from the DRI building (measured in a straight 

line). Also presented in Table 3.3-3 are the maximum numbers of cars seen in the station, the 

amount of fuel dispensed and the amount dropped on the ground following refueling. The 

station with the vapor recovery was a much busier station with more than twice the number 

of cars as the other station. The station used for refueling without vapor recovery (ME4) 

could refuel a maximum of four vehicles at one time, as it had two pumps and each pump 

could be used from either side. The station used for refueling with vapor recovery (ME3) 

could refuel a maximum of 8 vehicles at once, as it had two islands with two pumps each and 

each pump could be approached from either side. For all MEs we managed a relatively

consistent number of gallons dispensed which was possible since we could unload fuel from 

the van to a nearly constant level. For each refueling ME, we filled up until the automatic 

shutoff stopped the filling process. The number of drops spilled was not as consistent

partially due to the difficulty in precisely dropping a fixed amount of fuel out of the nozzle. 

The number in Table 3.3-3 is the number of drops spilled which was an approximate count of 

the number of wet spots noted on the pavement. The exception is the first ME where a large 

amount of fuel unexpectedly came out of the nozzle and left a single spot approximately 5 

cm in diameter. 

3-38
Table 3.3-3. Environmental Conditions for Refueling MEs. 

Fuel Tank Max. Cars Gallons Drops of Local

ME Date Start End Data Set Temp, C Humidity, % Temp, C In Station Dispensed Fuel Spilled Wind, mph Temp, C Winds

ME3 - Refueling w/ VR 4/29 04/29/03 12:00 12:20 avg. of 1st 10 minutes: 11 28 12

avg. of 2nd10 minutes: 11 28 13

Average of all 11 28 13 6 16.50 5 cm pool 5.9 7.4 1 - 2 mph

ME3 - Refueling w/ VR 4/30 04/30/03 10:45 11:05 avg. of 1st 10 minutes: 9 37 14

avg. of 2nd10 minutes: 9 36 15

Average of all 9 36 15 4 16.25 25 3.8 6.5 2 mph from SE

ME3 - Refueling w/ VR 5/01 05/01/03 12:25 12:45 avg. of 1st 10 minutes: 14 24 16

avg. of 2nd10 minutes: 14 24 16

Average of all 14 24 16 3 16.42 5 7.6 11.9 2 - 4 mph from SE var

ME3 - Refueling w/ VR 5/02 05/02/03 10:36 10:56 avg. of 1st 10 minutes: 11 53 15

avg. of 2nd10 minutes: 10 54 14

Average of all 11 53 15 5 15.40 10 2.5 8.5 < 1 mph, some drizzle

ME3 - Refueling w/ VR 5/05 05/05/03 10:45 11:05 avg. of 1st 10 minutes: 12 35 17

avg. of 2nd10 minutes: 12 35 16

Average of all 12 35 17 6 17.50 12 3.9 9.0 <1 mph from SSE

ME4 - Refueling w/o VR 4/3004/30/03 9:21 9:41 avg. of 1st 10 minutes: 14 28 14

avg. of 2nd10 minutes: 14 28 14

Average of all 14 28 14 3 15.80 6 2.9 3.6 1 - 2 mph from NNW

ME4 - Refueling w/o VR 4/3004/30/03 12:01 12:21 avg. of 1st 10 minutes: 12 30 16

avg. of 2nd10 minutes: 13 28 16

Average of all 13 29 16 1 15.40 12 3.2 7.9 2 - 4 mph variable dir.

ME4 - Refueling w/o VR 5/0 05/01/03 11:06 11:26 avg. of 1st 10 minutes: 15 22 14

avg. of 2nd10 minutes: 14 22 14

Average of all 14 22 14 1 14.18 3 6.6 9.8 2 - 3 mph from SSE

ME4 - Refueling w/o VR 5/0205/02/03 9:18 9:38 avg. of 1st 10 minutes: 11 42 18

avg. of 2nd10 minutes: 10 44 17

Average of all 11 43 18 2 17.31 12 3.5 8.7 1 - 2 mph, overcast

ME4 - Refueling w/o VR 5/0505/05/03 9:23 9:43 avg. of 1st 10 minutes: 17 28 18

avg. of 2nd10 minutes: 17 30 18

Average of all 17 29 18 1 14.50 20 3.9 8.3 < 1 mph from W

Sampling Point Measures

Ambient Conditions

(DRI Weather Station)

3-39
3.4 Reconstructed Data 

One of the objectives of this study was to determine if the original objective of using 

surrogate measures to determine the time series of compounds of interest was valid. To 

answer this question, this section details the reconstruction of the time series for benzene and

BTEX from the PID data and the comparison of this to the benzene and BTEX determined by 

the MS200 portable mass spectrometer. 

The procedure is first to average the 10 second data that is recorded by the PID 

instrument up to 1 minute data for comparison with the MS200 data set (1 minute 

increments). This time series is then used along with the integrated canister value to 

reconstruct a time series of the canister concentrations. To accomplish this, a ratio is taken

between the PID value at each point and the average PID value for the time series. This

number is multiplied by the integrated canister value to give a reconstructed value for that 

data point and is compared to the time-corresponding data point from the MS200. 

The first example presented is for the freeway driving (ME1) on 4/29/03. Figure 3.4-1 

shows the time series for benzene in this ME. A few data points are missing from the MS 

data where some electrical noise rendered those data points invalid. The general trend of the

peaks is reproduced by both the MS200 and the PID reconstructed data, however, the peak 

values are much higher in the MS200. This is confirmed by the comparison of the integrated 

values, where the MS200 showed 14.7 ppb and the canister 9.1. ppb. This ratio (1.6) nearly 

accounts for the differences and may be due to offset (zero point) or calibration differences in 

the MS200. Comparing the time series for the sum of the BTEX species, we obtain the plot 

in Figure 3.4-2. In this figure, the structure of the time series and the magnitude of the peaks

are both much more precisely reproduced than is the case with just benzene. Due to both the 

higher concentrations of toluene and the C8 benzenes, and the better performance of the

MS200 with these species. Section 3.1.9 details the performance of the MS200 versus the 

canisters and shows that benzene is consistently the most difficult species to measure,

especially at the lower levels. The integrated canister measurement for this sample was 97 

ppb for the sum of the BTEX species while the MS200 reported 123 ppb. Looking at the two 

highest peaks in this time series (8:01 and 8:03 am) it appears that the timing is slightly off 

with the MS200 lagging the PID reconstructed data. 

To further investigate the timing between these two instruments, we looked at a higher 

concentration sample with a significant spike in the concentration (ME4 refueling without 

vapor recovery from 5/2/03). Figure 3.4-3 shows the reconstructed time series for benzene 

along with the MS200 values for benzene. Figure 3.4-4 presents the same data for BTEX. In 

both figures, the series is well reproduced however the peak values recorded by the MS200

are much lower than the reconstructed. During the “non-peak” part of the ME, the MS200 

appears to be reading consistently higher than the reconstructed values. Overall, however, the 

values match quite well with the ratio of MS200/canister of 1.05 for the BTEX species and 

1.18 for benzene. As with the previous example, it appears that the timing of the peak 

concentration is out of phase by one minute. To look more closely at the peak concentration, 

we used the original 10 second data from the PID to reconstruct a 10 second time series for 

the BTEX species and plotted that along with the 1 minute data in Figure 3.4-5. This figure 

3-40
does not show the entire time series; rather it focuses on the period of the peak exposure from 

9:27 to 9:33 am. In this figure, the 10-second reconstructed data shows two peaks where the 

1-minute reconstructed and the MS200 data show one peak. The 1-minute time averaged data 

may better represent what the MS200 is measuring, since the MS200 does not integrate 

samples over the 1-minute period. Rather, the nature of the flow-through system smears the 

peaks out over a longer time due to the time it takes analytes to diffuse through the inlet 

system and into the mass analyzer. The flow-through system also means that some very short 

duration high peaks may not be seen at all. 

Overall the comparison of the reconstructed BTEX and MS200 BTEX values substantially 

agree and this provides added confidence that we can represent the peak exposures well by 

using the PID values to reconstruct time series for the BTEX species. While we do not have a 

direct measure for 1,3-butadiene, we would suggest that it could also be adequately 

represented by the PID values, especially for exhaust-dominated MEs. 

0

5

10

15

20

25

30

35

7:26 7:40 7:55 8:09 8:24

Time

ppbv

MS200 Benzene

Reonstructed Bz

Figure 3.4-1. ME1 (freeway driving) on 4/29/03: Time series of benzene from the MS200 

and reconstructed benzene concentrations from the PID and canister measurements. 

3-41
0

50

100

150

200

250

7:26 7:40 7:55 8:09 8:24

Time

ppbv

MS200 BTEX

Reonstructed BTEX

Figure 3.4-2. ME1 (freeway driving) on 4/29/03: Time series of BTEX from the MS200 and 

reconstructed BTEX concentrations from the PID and canister measurements. 

3-42
0

50

100

150

200

250

9:14 9:21 9:28 9:36 9:43

Time

ppbv

MS200 Benzene

Reonstructed Bz

Figure 3.4-3. ME4 (refueling without vapor recovery) on 5/2/03: Time series of benzene

from the MS200 and reconstructed benzene concentrations from the PID and canister 

measurements. 

3-43
0

200

400

600

800

1000

1200

1400

9:14 9:21 9:28 9:36 9:43

Time

ppbv

MS200 BTEX

Reonstructed BTEX

Figure 3.4-4. ME4 (refueling without vapor recovery) on 5/2/03: Time series of BTEX from 

the MS200 and reconstructed BTEX concentrations from the PID and canister measurements. 

3-44
0

1000

2000

3000

4000

5000

6000

7000

9:27 9:30 9:33

Time

ppbv

MS200 BTEX

Reonstructed BTEX

10 Sec BTEX

Figure 3.4-5. ME4 (refueling without vapor recovery) on 5/2/03: Time series of BTEX from 

the MS200 and reconstructed BTEX concentrations at both 1 minute and 10 second time

resolution. 

3-45
3.5 Breath Data 

Two subjects, labeled “B” and “J”, performed breath sample collections. The CO2 level in 

their breath samples was measured prior to the commencement of the pilot study, and 

averaged 5.4% for B and 6% for J. As described in Section 2.1, two breath samples were 

collected at refueling ME (prior to refueling and 10 sec after refueling), and three during each 

commuter traffic and garage test (before, after a peak exposure, and at the end of the ME 

sampling time). All breath samples were analyzed for CO2, BTEX, 1,3-butadiene, ethanol 

and MTBE as described in Section 2.3. The whole data set is presented in Appendix C. 

Figure 3.5–1 shows the CO2 values in the breath samples of subjects B and J collected in all 

ME, organized by the subject and by the microenvironment. It is clear that one pre- test 

freeway sample collected by J is invalid, since CO2 value is below 1%. Excluding this one 

sample, the mean CO2 value for subject B averages at 5.4%, and for subject J at 6.07% for

all ME. 

Figure 3.5-2A shows the concentrations of 1,3-butadiene, benzene, ethylbenzene, m/p- and oxylenes in the breath samples for all freeway tests (organized in the chronological order) and 

Figure 3.5-2B shows the concentrations of toluene and ethanol for the same ME. Figures 

3.5-3 A and B and Figure 3.5-4 A and B shows the same compound concentrations for the

garage and refueling ME, respectively. The range of concentrations for 1,3-butadiene, 

benzene, ethylbenzene, m/p- and o-xylenes agree reasonably well for both subjects, there is

clearly a large difference in the toluene concentrations. Subject B contains much higher 

toluene concentrations in the breath – it looks like the toluene is present in the breath of this 

subject, regardless of the exposure. The reason of this phenomenon is unknown to us. 

Ethanol concentrations are rather high and variable, not dependant on the exposure. MTBE 

concentrations are very low and are not shown on these figures. Neither MTBE nor ethanol 

are present in the Reno fuel at this time of the year. 

3-46
Carbon Dioxide

0123456789

%

----------------------------------------------------------- B --------------------------------------------------------------------------------------

---------------------------------------------------

Figure 3.5–1. CO2 values in the breath samples of subjects B and J collected in all ME, organized by microenvironment. 

3-47
Freeway

0

2

4

6

8

10

12

Freeway, Pre

Freeway, Peak

Freeway, Post

Freeway, Pre

Freeway, Peak

Freeway, Post

Freeway, Pre,J

Freeway, Peak,J

Freeway, Post,J

Freeway, Pre

Freeway, Peak

Freeway, Post

Freeway, Pre,J

Freeway, Peak,J

Freeway, Post,J

ppb

bud13

benze

etbz

mp_xyl

o_xyl

A

Freeway

0

20

40

60

80

100

120

140

160

Freeway, Pre

Free

way, Peak

Freeway, Post

Freeway, Pre

Free

way, Peak

Freeway, Post

Free

way, Pre,J

Free

way, Peak,J

Freeway, Post,J

Freeway, Pre

Free

way, Peak

Freeway, Post

Free

way, Pre,J

Free

way, Peak,J

Freeway, Post,J

ppb

tolue

ethoh

B

Figure 3.5-2. The concentrations of 1,3-butadiene, benzene, ethylbenzene, m/p- and oxylenes (A) and toluene and ethanol (B) in the breath samples of subject B (not labeled) and 

J in the freeway driving ME. The runs are shown in chronological order 

3-48
Garage

0

1

2

3

4

5

6

7

8

Garage, Pre

Garage, Peak

Garage, Post

Garage, Pre

Garage, Peak

Garage, Post

Garage, Pre,J

Garage, Peak,J

Garage, Post,J

Garage, Pre

Garage, Peak

Garage, Post

Garage, Pre,J

Garage, Peak,J

Garage, Post,J

ppb

bud13

benze

etbz

mp_xyl

o_xyl

A

Garage

0

20

40

60

80

100

120

140

160

180

Garage, Pre

Garage, Peak

Garage, Post

Garage, Pre

Garage, Peak

Garage, Post

Garage, Pre,J

Garage, Peak,J

Garage, Post,J

Garage, Pre

Garage, Peak

Garage, Post

Garage, Pre,J

Garage, Peak,J

Garage, Post,J

ppb

tolue

ethoh

B

Figure 3.5-3. The concentrations of 1,3-butadiene, benzene, ethylbenzene, m/p- and oxylenes (A) and toluene and ethanol (B) in the breath samples of subject B (not labeled) and 

J in the garage ME. The runs are shown in chronological order 

3-49
Refueling

0

5

10

15

20

Ref. W/O

V, Pre

Ref. W/O

V, Post

Ref. W/O

V, Pre

Ref. W/O

V, Post

Ref. W/O V, Pre,J

Ref. W/O V, Post,J

Ref. W/O

V, Pre

Ref. W/O

V, Post

Ref. W/O V, Pre,J

Ref. W/O V, Post,J

Ref. W/V, Pre

Ref. W/V, Post

Ref. W/V, Pre

Ref. W/V, Post

Ref. W/V, Pre,J

Ref. W/V, Post,J

Ref. W/V, Pre

Ref. W/V, Post

Ref. W/V, Pre,J

Ref. W/V, Post,J

ppb

bud13

benze

etbz

mp_xyl

o_xyl

80 ppb

A

Refueling

0

50

100

150

200

250

Ref. W/O V, Pre

Ref. W/O V, Post

Ref. W/O V, Pre

Ref. W/O V, Post

Ref. W/O V, Pre,J

Ref. W/O V, Post,J

Ref. W/O V, Pre

Ref. W/O V, Post

Ref. W/O V, Pre,J

Ref. W/O V, Post,J

Ref. W/V, Pre

Ref. W/V, Post

Ref. W/V, Pre

Ref. W/V, Post

Ref. W/V, Pre,J

Ref. W/V, Post,J

Ref. W/V, Pre

Ref. W/V, Post

Ref. W/V, Pre,J

Ref. W/V, Post,J

ppb

tolue

ethoh

B

Figure 3.5-4. The concentrations of 1,3-butadiene, benzene, ethylbenzene, m/p- and oxylenes (A) and toluene and ethanol (B) in the breath samples of subject B (not labeled) and 

J during refueling. The runs are shown in chronological order 

3-50
3.6 Consistency of Microenvironment Conditions 

Each of the four microenvironments included in this pilot study was repeated 5 times to 

assess the variability of the environmental conditions and precision of the characterization 

methods. During the testing periods there were no significant variations in meteorological 

conditions and the same protocols were observed, so it is reasonable to attribute any 

variations in the range or magnitude of measurements to differences in activity in the

microenvironment, daily variations in background concentrations, or measurement 

uncertainty. Statistical summaries of the continuous CO and BTEX by PID data are presented

in this section to examine this variability. The statistics represented are the maximum and 

mean of the running 1 minute averages of the continuous concentration measurements 

recorded every 10 seconds during each test. The 10th and 90th percentile values for each test 

are also represented to give a better representation of the range of concentrations observed. 

Charts of the average for each microenvironment and standard deviation of the average

among the 5 replicates are also included in Figure 3.6-3. 

3.6.1 CO 

Figure 3.6-1 shows the API NDIR CO data except for the first two repetitions of ME1 and 

the first ME3 for which the NDIR data was invalid because of insufficient battery. For those

three tests discrete 1 minute averages from the electrochemical CO instrument are

summarized in the chart.

The range of concentrations is large for all tests, with the exception of several of the 

refueling tests (ME3 and ME4) where CO concentrations were near background throughout 

the tests. Despite the large range, the differences between microenvironments are clearly

evident. The parking garage tests, ME2, had higher maximum and 90th percentile 

concentrations than all but one of the freeway tests even though the average concentrations 

are similar. The two refueling MEs are consistently lower than the freeway or garage in both 

the mean and maximum values. The third freeway (ME1) test appears to be an outlier due to 

a high initial level of CO (see Figure 3.2-4), possibly a result of capturing exhaust from the

van in the cabin prior to the start of the driving cycle. 

3-51
0

5

10

15

20

25

ME1 ME2 ME3 ME4

1 m inute running a

vg C

O (ppm )

10th to

90th %

MAX

MEAN

Figure 3.6-1. Range and variability of CO concentration during tests. Statistics for each of 

the five replicate tests are shown for each microenvironment. 

Data summarized are running 1-minute averages (at 10 second intervals) of NDIR CO data, 

except for the first two ME1s and first ME3 which are discrete 1 minute averages from the 

electrochemical CO instrument. The shaded bars indicate the range from the 10th to 90th 

percentile. Microenvironments are: freeway driving (ME1), parking garage (ME2), refueling 

with vapor recovery (ME3), and refueling without vapor recovery (ME4).

3-52
3.6.2 PID 

The range and variability of BTEX concentrations estimated by the primary ppbRAE VOC 

monitor (PID1) are summarized in Figure 3.6-2. As with CO, the range of the mean and 

maximum values is large for all tests, but still smaller than the overall difference between 

microenvironments. The largest range occurred for refueling without vapor recovery (ME4), 

which is to be expected since very high VOC levels occurred during the refueling process. In 

all cases, the 10th percentile values were near the lower limit of detection (they appear to be

zero in the chart due to scale) suggesting that background levels of BTEX were very low. 

3-53
0

20 00

40 00

60 00

80 00

100 00

120 00

140 00

160 00

180 00

M E 1 M E 2 M E 3 M E 4

1 m inute running avg 

B

T

E

X by PID (ppb)

10 th to

90 th %

M A X

M E A N

0

10 0

20 0

30 0

40 0

50 0

60 0

70 0

80 0

90 0

100 0

ME1 M E2 M E3 M E 4

1 m inute running avg B

TEX by PID (ppb)

10 th to

90 th %

MAX

MEAN

Figure 3.6-2. Range and variability of BTEX by PID concentration during tests. 

Statistics for each of the five replicate tests are shown for each microenvironment. Data 

summarized are running 1-minute averages (at 10 second intervals) The shaded bars indicate 

the range from the 10th to 90th percentile. The lower chart shows the same data on an 

expanded scale. Microenvironments are: freeway driving (ME1), parking garage (ME2), 

refueling with vapor recovery (ME3), and refueling without vapor recovery (ME4). 

3-54
Average of replicate test mean c onc entrations

0

1

2

3

4

5

6

7

8

9

ME1 ME2 ME3 ME4

CO (

p

p

m )

0

200

400

600

800

1000

1200

1400

ME1 ME2 ME3 ME4

BTEX by PI

D (p pb)

Figure 3.6-3. Range and variability of mean CO and mean BTEX by PID concentration for 

four microenvironments. 

Data summarized are running 1-minute averages (at 10 second intervals) The error bars 

indicate the standard deviation of the average of five replicate tests. Microenvironments are: 

freeway driving (ME1), parking garage (ME2), refueling with vapor recovery (ME3), and 

refueling without vapor recovery (ME4). 

3-55
4. CONCLUSIONS 

Overall, the 2nd Reno Pilot study was a success. Specifically, we completed the stated goal 

of the study: to demonstrate the proper operation and reliability of analytical instrumentation 

and comparability of time-integrated, semi-continuous and continuous methods for 

compounds of interest. In addition, we demonstrated the validity of the method of 

reconstructing time series for compounds of interest by using surrogate measurements. In this 

case, we specifically demonstrated the validity of using the PID signal and the canister data 

to reconstruct the time series for BTEX. 

The following conclusions are drawn from the 2nd Reno Pilot Study results: 

Modifications to the sampling van and addition of the data acquisition system were 

significant improvements that allowed for more complete data collection. The new 

power system does not produce artifacts; however, it is insufficient to power the API 

CO instrument. Possible alternatives include use of a different brand of NDIR CO or 

the addition of more battery banks to support the API NDIR CO. Several 

improvements are still planned to the sampling van including the addition of a 

continuously logged barometric pressure sensor, direct logging of flow to the 

integrated samplers, and logging of canister pressure. 

Data capture was generally quite good with near 100% data capture for the reference 

samples, canisters, DNPH and solid adsorbent. The SPME also had excellent data 

capture, as did the continuous instruments for CO and PID. The MS200 performed 

well in the beginning of the study however at the end it was not working. The 

supplemental continuous formaldehyde instrument is not reliable during mobile 

measurements, and should only be used for stationary measurements. Our 

environmental monitoring equipment for temperatures, humidity, etc., lost only 14 

minutes of data over the entire study. 

The MS200 generally performed well against the canister when comparing the 

average value from the MS to the integrated canister measurement for the same ME. 

However, there are still concerns with this supplemental measurement system. There 

appears to be a concentration bias, especially for benzene. The instrument appears to 

miss very rapid changes in concentration such as those that occur during refueling

events. There are still some electrical noises that appear in the van when in motion. 

We did not detect these in the stationary MEs, and they did not invalidate more than a 

few spectra in a run. The MS200 did not run during the last day of the study due to 

several factors relating to the sensitivity of the detector and the filament voltage

control. Some of this appears to be electronic related and may be fixed when we send 

the electronics box back to be upgraded to the new interface. The MS200 is a 

developing instrument that should provide interesting supplemental data to the study. 

The continuous formaldehyde analyzer worked well for two of the five garage 

sampling microenvironments (ME2-4 and ME2-5) but did not work well for the

freeway (ME1) or refueling (ME3 and ME4) microenvironments. The sensitivity of

the instrument to environmental noise associated with driving while collecting data 

may limit its utility under any sort of mobile environment. With proper operation and 

4-1
better characterization of instrument performance, the supplemental continuous 

formaldehyde analyzer may prove useful for monitoring a stationary environment. 

Both an EPA-certified gas-filter correlation NDIR CO analyzer (API model 300) and 

a portable battery-operated passive electrochemical cell instrument (Langan T15v) 

agree reasonably well to within about 1 ppm. During low-ventilation (half of the

freeway tests) the CO concentrations remain at or decrease toward the lowest level 

measured during the high-vent phase. This behavior suggests that no in-cabin sources

or interferences are present. 

In general the continuous PID and CO instruments performed very well. The two 

PIDs were compared both in controlled tests and collocated 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 speed between the two units. The NDIR CO 

and electrochemical CO instruments compared favorably, usually within 1 ppm. This

was partially attributed to the adaptive filtering of the API NDIR CO as demonstrated

when comparing it to another NDIR instrument made by Monitor Labs, Inc. For the 

purposes of this study, we strongly recommend using an instrument without the 

adaptive filter since the filter causes changes in concentration to appear less sharp 

than actual and causes peaks to shift to later times which interferes with 

intercomparisons among methods and instruments. 

Comparison of CO from the continuous instruments to that measured by GC from the 

canisters showed that the canister CO was generally 8% higher with no consistent

bias correlated to any particular ME nor with concentration. The correlation between 

the CO and PID data was strongest for the garage ME. 

SPME samples show overall higher concentrations than MS200 (10-min averaged)

concentrations. Also, SPME data averaged over the entire sampling periods are 

generally higher than canister data, due possibly to inadequate temperature 

corrections of the SPME data. SPME fibers are very sensitive to temperature changes

(they absorb more analytes under cold conditions, as in this pilot study) and they 

might not be fully equilibrated to ambient temperatures prior to sampling. In the 

future study, the clean fibers will be stored at ambient temperature in a closed

container with activated charcoal. 

The procedure for collecting and analyzing breath samples worked well; there was 

only one invalid sample (based on CO2 concentration) during this study. The data 

shows consistently higher BTEX concentrations after the peak exposure and are 

comparable between the two subjects collecting the samples. One exception is toluene 

where it appears that one of the subjects has toluene present in the breath samples, 

regardless of the exposure. 

The 5-minute canister samples had lower data recovery (80%). This was partially 

because the sampler that was used to fill this canister was not optimal for the task. A

relatively high flow rate was needed to pressurize a canister in only 5 min and the 

sampler used was not designed for this much flow. For the final study, we have

designed and built a new sampler specifically for this task. 

4-2
The reconstruction of the benzene and BTEX time series from the PID data showed

overall good comparison with the MS200 data. However, some concentration peaks

were not reproduced in magnitude and appeared to be time shifted, a consequence of 

the averaging of the PID data from 10 seconds down to 1 minute. In addition, the 

MS200 does not integrate samples over the 1-minute period; rather the nature of the 

flow-through system smears the peaks over a longer period due to the time it takes to 

diffuse through the inlet system and into the mass analyzer. Because of the flowthrough system, very short duration high peaks may not be seen. In summary, for 

most of the MEs the reconstructed data and the MS200 data agreed reasonably well, 

suggesting that the reconstruction method works and should provide a method to 

calculate the peak exposures during sampling at the MEs. 

4-3
5. REFERENCES: 

Chai, M. and J. Pawliszyn, 1995. Analysis of Environmental Air Samples by Solid-Phase 

Microextraction and Gas Chromatography/Ion Trap Mass Spectrometry, 

Environmental Science and Technology, Vol. 29, No. 3. Pag 693-701. 

Grote C.and J.Pawlinszyn, 1997. Solid Phase Microextraction for the analysis of Human 

Breath. Anal Chem.. Volume 69, 587-596 

Kelly, T.J. and C.R. Fortune (1994). Continuous Monitoring of Gaseous Formaldehyde 

Using an Improved Fluorescence Approach. Intern. J. Environ. Anal. Chem., 54: 

249-263 

Koziel, Jaceb, et al., 1999 Field air analysis with SPME device. Analytical Chimica Acta 400 

153-162 

Koziel, Jacek A. and Novak, I. 2002. Sampling and Sample-preparation Strategies Based on 

Solid-phase Microextraction for Analysis of Indoor Air. Trends in Analytical 

Chemistry, Vol 21, No.12. 

Lodge, James P. Methods of air sampling and analysis. Third edition. Lewis publishers. 

Intersociety committee. Michigan, 1989. pp15-16. 

Martos, P. and J. Pawliszyn, 1997. Calibration of Solid Phase Microextraction for Air 

Analysis Based on Physical Chemical Properties of the Coating. . Analytical 

Chemistry. 69: 206-215. 1997 

Martos, P. and J. Pawliszyn, 1999. Time-Weighted Average Sampling with Solid-Phase 

Microextraction Device: Implications for Enhanced Personal Exposure Monitoring to 

Airborne Pollutants, Analytical Chemistry, Vol. 71, No. 8, April 15. 

McLaren and Zhou, 2000. Measurement of Oxygenated Hydrocarbons in Outdoor Air using 

Sold-Phase Microextraction Gas Chromatography. AAA Conference 2000. 

Namiesnik, Jacek. Generation of standard gaseous mixtures. Journal of Chromatography. 

300. 1984. pp. 79-108. 

Nelson, Gary O. Gas Mixtures: Preparation and Control. Lewis Plublishers. 1992. CRC 

Press. 

Parreira, F et al. Evaluation of Indoor Exposition to BTEX and Styren by passive sampling 

with SPME. Journal of Chromatography, Vol. 40, March 2002. 122-126. 

Pawliszyn, J., 1997. Solid Phase Microextraction: Theory and Practice, Wiley-VCH. 

Pawliszyn, J., 1999. Applications of Solid phase Microextraction. Royal Society of

Chemistry. 

Pawliszyn, 2002. Sampling and Sample Preparation for Field and Laboratory. 

Comprehensive Analytical Chemistry, Vol 37. Elsevier. 

5-4
Pleil J.D. and A. B. Lindstrom. (1995). Measurement of volatile organic compounds in 

exhaled breath as collected in evacuated electropolished canisters. J. Chromatogr. B, 

665: 271-279 

Tuduri, Ludovic et al. Potential of Sollid-Phase Microextraction fibers for the Analysis of 

VOC in air. Journal of Chromatographic Science, Vol. 39, December 2001. pp 521-

529. 

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

Exposure Screening Study of Baseline and Oxygenated Gasoline - Summer 2002 

Atlanta Field Study on Baseline Gasoline. Feb. 2003 

Zielinska, B., E. M. Fujita, J. C. Sagebiel, D. E. Campbell, J. D. McDonald, L. R. Smith, T. 

Johnson (2002). Exposure Protocol and Study Plan for the Section 211(B) Tier 2 

High End Exposure Screening Study of Baseline and Oxygenated Gasoline. Revisied 

edition,Sept.30,2002

5-5
6.APPENDICIES 

6.1 Appendix A: SPME 

ppb

me date strthhmm stophhmm an_date Storage Tavg RHavg benze tolue etbz mp_xyl o_xyl

ME3 4/29/03 1210 1220 4/29/03 2:40 10.69 28.03 6.66 47.13 10.18 29.32 7.99

ME3 4/29/03 1200 1210 4/29/03 3:15 10.69 28.03 17.21 58.56 11.22 24.76 12.06

ME1 4/29/03 812 822 4/29/03 7:33 20.78 31.90 18.80 114.09 19.42 51.10 15.56

ME1 4/29/03 802 812 4/29/03 8:18 15.80 31.81 12.50 98.24 18.51 51.17 16.44

ME1 4/29/03 752 802 4/29/03 9:08 12.32 31.89 15.69 70.86 15.95 45.05 14.50

ME1 4/29/03 742 751 4/29/03 9:38 11.71 37.73 13.12 66.47 19.61 54.81 17.34

ME2 4/29/03 1652 1702 4/29/03 1:08 10.28 34.59 24.70 66.85 19.49 49.33 14.83

ME2 4/29/03 1702 1712 4/29/03 1:28 10.08 35.88 28.21 90.12 26.36 73.08 25.69

ME2 4/29/03 1642 1652 4/29/03 2:18 10.56 34.60 4.08 12.49 2.48 6.95 1.59

ME4 4/30/03 1211 1221 4/30/03 1:04 27.68 12.82 11.74 65.18 15.12 34.53 7.41

ME4 4/30/03 1201 1211 4/30/03 1:34 29.14 12.21 10.29 38.17 13.10 28.02 7.16

ME3 4/30/03 1045 1055 4/30/03 3:15 8.93 36.59 6.61 24.51 6.31 20.73 5.50

ME3 4/30/03 1055 1105 4/30/03 3:35 8.99 36.32 2.71 16.40 7.55 18.23 4.50

ME1 4/30/03 809 819 4/30/03 6:36 25.54 25.88 20.41 155.78 22.19 66.59 19.90

ME1 4/30/03 759 809 4/30/03 7:11 20.69 28.02 21.92 139.74 30.27 80.99 27.37

ME1 4/30/03 739 749 4/30/03 7:56 9.72 42.59 27.17 113.76 33.86 84.96 27.28

ME1 4/30/03 749 759 4/30/03 8:26 12.98 34.35 26.52 101.84 14.13 59.19 18.05

ME4 4/30/03 921 931 4/30/03 7:39 14.10 27.98 17.04 85.61 15.34 57.68 17.01

ME4 4/30/03 931 941 4/30/03 7:49 14.03 28.33 41.04 140.14 20.70 75.84 22.48

ME2 4/30/03 1645 1655 4/30/03 3:35 32.77 11.59 28.60 89.19 13.52 49.40 16.85

ME2 4/30/03 1655 1705 4/30/03 3:45 32.71 10.84 19.14 69.59 16.89 58.29 19.66

ME2 4/30/03 1705 1715 4/30/03 3:55 33.04 11.07 64.00 173.74 48.88 154.57 58.11

ME1 5/1/03 720 730 5/1/03 2:30 11.32 43.40 49.70 152.00 36.87 104.52 34.61

ME1 5/1/03 750 800 5/1/03 2:30 21.41 33.72 29.58 195.04 24.92 81.88 26.47

ME1 5/1/03 730 740 5/1/03 3:10 15.96 30.60 29.78 130.20 26.21 87.38 28.80

ME1 5/1/03 740 750 5/1/03 3:30 19.82 30.06 21.32 110.07 19.09 63.33 23.26

ME4 5/1/03 1116 1126 5/1/03 2:44 13.72 21.79 8.05 54.91 14.50 44.03 12.10

ME4 5/1/03 1106 1116 5/1/03 3:24 14.50 22.27 5.55 43.57 14.64 35.20 8.71

ME3 5/1/03 1225 1235 5/1/03 2:20 13.54 24.52 5.61 17.02 4.60 13.58 3.23

ME2 5/1/03 1647 1656 5/1/03 1:13 14.92 24.64 6.53 38.15 8.80 23.63 6.48

ME2 5/1/03 1707 1717 5/1/03 1:13 16.18 35.42 24.17 83.75 16.99 56.15 20.52

ME2 5/1/03 1657 1707 5/1/03 2:03 14.31 25.74 30.28 91.61 15.95 58.19 19.01

ME3 5/2/03 1036 1046 5/2/03 2:39 10.76 52.57 33.56 94.44 16.85 61.89 19.50

ME3 5/2/03 1046 1056 5/2/03 2:59 10.34 53.49 7.32 39.96 7.48 23.74 5.97

ME3 5/2/03 918 928 5/2/03 4:52 10.77 42.35 4.85 27.41 6.35 18.09 4.01

ME3 5/2/03 928 938 5/2/03 5:12 10.48 43.85 84.69 281.09 56.15 167.71 54.37

ME1 5/2/03 735 745 5/2/03 7:40 16.18 35.42 16.85 83.28 20.74 56.96 17.37

ME1 5/2/03 745 755 5/2/03 8:15 19.57 29.39 22.92 121.35 30.46 86.71 27.35

ME1 5/2/03 745 805 5/2/03 8:20 22.74 29.85 28.56 104.73 18.11 55.28 16.95

ME1 5/2/03 805 815 5/2/03 8:35 22.95 33.30 22.15 149.75 29.73 69.31 22.45

6-1
ME2 5/2/03 1645 1655 5/2/03 1:30 14.18 47.03 4.21 19.10 5.85 18.00 5.11

ME2 5/2/03 1655 1705 5/2/03 1:40 13.67 47.85 7.92 26.49 5.24 13.67 4.05

ME1 5/5/03 750 800 5/5/03 5:00 14.99 39.76 15.94 75.70 17.13 53.58 16.78

ME1 5/5/03 800 810 5/5/03 5:10 17.22 33.13 15.05 66.46 0.00 0.00 0.00

ME1 5/5/03 820 830 5/5/03 6:20 21.77 38.99 21.32 151.16 12.04 46.64 13.37

ME1 5/5/03 810 820 5/5/03 6:50 19.78 35.90 24.70 138.72 25.47 90.35 30.36

ME4 5/5/03 923 933 5/5/03 5:57 17.46 28.63 1.76 10.36 1.61 5.98 1.23

ME4 5/5/03 933 943 5/5/03 6:07 16.70 29.65 103.75 386.16 34.98 121.64 31.29

ME 3 5/5/03 1045 1055 5/5/03 5:15 12.42 35.10 4.94 14.62 2.06 8.31 1.89 

ME 3 5/5/03 1055 1105 5/5/03 5:25 12.31 35.33 6.55 21.64 2.92 11.16 2.29 

ME2 5/6/03 1645 1655 5/6/03 1:10 13.70 33.79 4.95 17.18 2.82 9.78 2.06

ME2 5/6/03 1655 1705 5/6/03 1:20 13.49 34.22 1.39 1.26 0.32 1.07 0.23

ME2 5/6/03 1705 1715 5/6/03 1:30 13.59 34.62 12.52 48.73 14.31 51.91 18.25

avg 4:29 16.54 32.25

max 9:38 33.04 53.49

min 1:04 8.93 10.84

6-2
C2-C12 Hydrocarbons Target List 

Mnemonics Names Formula MW Group

1 ETHENE ethene C2H4 28.05 O

2 ACETYL acetylene C2H2 26.04

3 ETHANE ethane C2H6 30.07 P

4 PROPE Propene C3H6 O

5 N_PROP n-propane C3H8 44.10 P

6 I_BUTA isobutane 58.12 P

7 LIBUTE isobutene C4H8 56.11 O

8 LBUT1E C4H8 56.11 O

9 BUDI1,3 1,3-butadiene C4H6 54.1 O

10 n-butane C4H10 58.12 P

11 T2BUTE t-2-Butene C4H8 56.11 O

C2BUTE c-2-butene C4H8 56.11 O

13 IPENTA isopentane C5H12 72.15 P

14 PENTE1 1-pentene C5H10 70.13 O

15 N_PENT n-pentane C5H12 72.15

16 I_PREN isoprene C5H8 68.11 O

17 T2PENE t-2-Pentene C5H10 O

18 C2PENE c-2-pentene C5H10 70.13 O

19 BU22DM 2,2-dimethylbutane 86.17 P

20 CPENTA cyclopentane C5H10 70.13 P

21 BU23DM C6H14 86.17 P

22 PENA2M 2-methylpentane C6H14 86.17 P

23

6.2 Appendix B: Canisters and Tenax 

Y

42.08

C4H10

1-butene

N_BUTA

12

P

70.13

C6H14

2,3-dimethylbutane

PENA3M 3-methylpentane C6H14 86.17 P

24 P1E2ME 2-methyl-1-pentene C6H12 84.16 O

25 N_HEX n-hexane C6H14 86.17

26 MCYPNA Methylcyclopentane C6H12 84.16 P

27 PEN24M 2,4-dimethylpentane C7H16 100.20

28 BENZE benzene C6H6 78.11 A

29 CYHEXA cyclohexane C6H12 84.16

30 HEXA2M 2-methylhexane C7H16 98.19 P

31 PEN23M

P

P

P

2,3-dimethylpentane C7H16 100.20 P

32 HEXA3M 3-methylhexane C7H16 100.20 P

33 PA224M 2,2,4-trimethylpentane C8H18 114.23 P

34 N_HEPT n-heptane C7H16 100.20 P

35 MECYHX methylcyclohexane C7H14 98.19 P

36 PA234M 2,3,4-trimethylpentane C8H18 114.23 P

37 TOLUE toluene C7H8 92.14 A

38 HEP2ME 2-methylheptane C8H18 114.23 P

39 HEP3ME 3-methylheptane C8H18 114.23 P

40 N_OCT n-octane C8H18 114.22 P

41 ETBZ ethylbenzene C8H10 106.16 A

42 MP_XYL mp-xylene C8H10 106.16 A

43 STYR styrene C8H8 104.14 A

44 O_XYL o-xylene C8H10 106.17 A

45 N_NON n-nonane C9H20 128.26 P

6-3
46 IPRBZ isopropylbenzene C9H12 120.20 A

47 N_PRBZ n-propylbenzene C9H12 120.20 A

48 M_ETOL m-ethyltoluene C9H12 120.20 A

49 P_ETOL p-ethyltoluene C9H12 120.20 A

50 BZ135M 1,3,5-trimethylbenzene C9H12 120.20 A

51 O_ETOL o-ethyltoluene C9H12 120.20 A

52 BZ124M 1,2,4-trimethylbenzene C9H12 120.20 A

53 N_DEC n-decane C10H22 142.29 P

54 BZ123M 1,2,3-trimethylbenzene C9H12 120.20 A

55 DETBZ1 m-diethylbenzene C10H14 134.22 A

56 DETBZ2 p-diethylbenzene C10H14 134.22 A

57 N_UNDE n-undecane C11H24 156.30 P

58 MTBE methyl t-butyl ether C5H12O 88.14 E

TNMHC

A = aromatic, AL = Aldehyde, O = alkene (olefin), P = parafin, Y = alkyne, K = ketone, 

E = ether, X = haogenated, OH = alcohol 

6-4
Concentrations in ppbC, Tenax 

site date starthhmm stophhmm duration

(min)

ethoh mtbe tolue etbz mp

Freeway 4/29/03 0742 0822 40 0.00 0.00 215.22 43.24 Freeway 4/29/03 0742 0822 40 0.00 0.00 229.54 44.83 Refueling W/Vapor Re 4/29/03 1200 1220 20 0.00 0.00 82.06 11.65 Garage 4/29/03 1642 1712 30 4.24 0.00 105.02 23.08 Freeway 4/30/03 0739 0819 41.1 0.00 0.00 342.38 64.43 Refueling W/O Vapor 4/30/03 0921 0941 19.92 0.00 0.00 240.68 38.40 Refueling W/Vapor Re 4/30/03 1045 1105 20 0.00 0.00 19.61 4.20 Refueling W/O Vapor 4/30/03 1205 1225 20 0.00 0.00 49.12 5.20 Garage 4/30/03 1645 1715 30 0.00 0.00 187.19 47.86 Refueling W/O Vapor 5/1/03 1106 1126 20.43 0.00 0.00 146.48 10.89 Refueling W/Vapor Re 5/1/03 1225 1245 21.3 0.00 0.00 35.57 6.67 Garage 5/1/03 1647 1717 30 0.00 0.00 222.61 54.49 Freeway 5/2/03 0735 0815 40 0.00 0.00 238.47 39.24 Refueling W/O Vapor 5/2/03 0918 0938 20 0.00 0.00 330.84 53.26 Refueling W/Vapor Re 5/2/03 1036 1056 20 0.00 0.00 51.20 11.93 Garage 5/2/03 1645 1715 30 0.00 0.00 137.43 36.88 Garage 5/2/03 1645 1715 30 0.00 0.00 159.00 40.65 Garage-Blank 5/2/03 1710 1710 0 0.00 0.00 0.19 0.00 Freeway 5/5/03 0750 0830 40 0.00 0.00 396.27 81.14 Refueling W/O Vapor 5/5/03 0923 0943 20 0.00 0.00 270.81 24.47 Refueling W/Vapor Re 5/5/03 1045 1105 20 0.00 0.00 10.47 2.37 Garage 5/6/03 1645 1715 30 0.00 0.00 43.20 11.77 

6-5
Canister BTEX, ppbC 

site date time Time (min) an_type budi13 benze tolue etbz Freeway 4/29/03 742-822 20 p 10.78 54.57 317.43 59.84 Refueling W/Vapor Recovery 4/29/03 1200-1205 5 p 8.86 15.35 88.97 14.96 Refueling W/Vapor Recovery 4/29/03 1200-1205 5 r 8.79 15.52 91.18 15.33 Refueling W/Vapor Recovery 4/29/03 1200-1220 20 p 1.15 20.27 69.36 11.46 Garage 4/29/03 1642-1712 20 p 6.78 33.88 102.67 24.81 Refueling W/Vapor Recovery 4/30/03 1045-1105 20 p 0.99 7.74 31.64 7.79 Refueling W/Vapor Recovery 4/30/03 1045-1105 20 r 0.99 7.84 31.81 7.8 Refueling W/Vapor Recovery 4/30/03 1055-1100 5 p 0.83 16.7 88.09 17.5 Refueling W/O Vapor Recovery 4/30/03 1205-1245 20 p 0.53 12.8 54.95 9.17 Refueling W/O Vapor Recovery 4/30/03 1212-1217 5 p 0.14 6.97 23.5 3.01 Garage 4/30/03 1645-1715 20 p 11.52 59.62 223.45 55.82 Freeway 4/30/03 739-819 20 p 12.67 60.04 376.27 69.5 Refueling W/O Vapor Recovery 4/30/03 921-927 20 p 1.41 247.58 708.8 71.8 Refueling W/O Vapor Recovery 4/30/03 921-941 20 p 1.08 56.75 239.86 44.01 Refueling W/O Vapor Recovery 5/1/03 1106-1126 20 p 0.66 14.02 70.68 14.6 Refueling W/O Vapor Recovery 5/1/03 1117-1123 5 p 0.89 132.77 385.71 37.26 Refueling W/Vapor Recovery 5/1/03 1225-1245 20 p 1.06 9.66 43.99 9.62 Garage 5/1/03 1642-1717 20 p 13.18 63.78 239.78 57.81 Freeway 5/1/03 720-800 20 p 21.38 109.66 534.75 99 Freeway 5/1/03 720-800 20 r 20.43 107.86 523.17 97.41 Refueling W/Vapor Recovery 5/2/03 1036-1056 20 p 0.6 13.78 64.99 16.76 Refueling W/Vapor Recovery 5/2/03 1046-1051 5 p 0.19 4.97 35.09 16 Garage 5/2/03 1645-1715 20 p 6.93 31.72 119.67 30.29 Freeway 5/2/03 735-815 20 p 10.22 43.61 215.65 38.17 Refueling W/O Vapor Recovery 5/2/03 918-938 20 p 49.8 122.93 419.54 65.06 Refueling W/O Vapor Recovery 5/2/03 929-934 5 p 2.94 458.68 1320.65 199.46 Refueling W/Vapor Recovery 5/5/03 1045-1105 20 p 0.54 9.3 50.59 11.11 Refueling W/Vapor Recovery 5/5/03 1055-1100 5 p 1.33 14.65 82.79 16.5 Freeway 5/5/03 750-830 20 p 10.66 57.6 312.85 66.46 Refueling W/O Vapor Recovery 5/5/03 923-943 20 p 1.38 419.62 1093.91 101.8 Garage 5/6/03 1645-1715 20 p 6.35 29.18 99.13 26 

6-6
Canisters - Full C2-C12 Speciation (ppbC) 

site Refueling

W/VaporRecovery

Refueling

W/VaporRecovery

RefuelingW/O VaporRecovery

RefuelingW/VaporRecovery

RefuelingW/O VaporRecovery

RefuelingW/O VaporRecovery

RefuelingW/VaporRecovery

RefuelingW/O VaporRecovery

RefuelingW/O VaporRecovery

RefueliW/VapRecove

date 4/30/03 4/30/03 4/30/03 5/5/03 5/5/03 4/30/03 4/29/03 5/2/03 5/1/03 5

time 1045-1105 1045-1105 921-941 1045-1105 923-943 1205-1245 1200-1220 918-938 1106-1126 1225-1

an_type p r p p p p p p p p 

canister C073 C073 C095 C136 C186 C085 C046 C153 C227 C076 

ethane 5.20 5.26 8.83 4.58 34.04 5.38 5.91 14.87 4.60 ethene 10.82 10.93 6.98 5.70 5.32 5.48 10.96 11.46 4.09 

acetyl 35.90 37.30 13.60 12.67 4.10 14.69 28.90 20.41 5.22 2

prope 4.42 4.41 20.39 3.04 555.07 6.25 9.43 84.86 3.66 n_prop 3.03 3.04 44.31 3.37 654.88 22.07 11.72 138.73 9.06 i

_

buta 8.39 8.37 292.11 8.36 3119.11 49.79 76.51 781.1 85.79 3

lbut1e 1.02 1.02 14.77 0.64 68.50 2.32 4.04 25.06 10.58 libute 1.69 1.67 53.12 0.60 335.61 7.86 0.00 127.69 5.55 budi13 0.99 0.99 1.08 0.54 1.38 0.53 1.15 49.8 0.66 n_buta 42.97 42.25 1350.13 52.08 15644.09 217.4 398.79 3806.37 354.28 1

t2bute 1.44 1.5 49.99 1.13 404.02 9.16 12.28 114.96 17.44 

c2bute 0.79 0.83 31.44 1.58 179.85 4.11 7.23 53.98 11.38 ipenta 99.66 99.21 3079.3 99.96 25116.14 557.31 812.57 8387.13 474.96 23

pente1 1.31 1.41 77.4 4.41 428.6 7.33 14.96 150.06 10.49 n_pent 16.7 16.89 496.47 17.43 4118.19 83.55 137.59 1229.93 83.29 4

i

_pren 0.47 0.47 1.43 0.41 3.58 0.85 1 1.35 0.69 

t2pene 8.53 8.59 253.28 9.08 1998.16 42.71 72.47 596.83 45.39 2c2pene 3.42 4.02 100.55 3.73 795.77 16.87 29.41 235.57 18.81 1bu22dm 2.04 1.99 41.61 2.52 370 8.72 11.7 116.55 6.16 cpenta 1.91 1.85 42.07 2.44 386.01 8.45 11.17 112.46 8.76 bu23dm 3.12 3.16 73.75 4.58 623.65 12.01 23.03 170.65 14.37 pena2m 12.57 12.62 265.51 19.01 2433.1 48.16 81.18 653.25 50.35 2

pena3m 7.56 8.25 149.77 11.81 1379.42 27.49 46.61 366.92 28.7 1p1e2me 0.9 0.9 12.44 1.52 156.27 2.4 3.8 28.52 3.37 

n_hex 5.32 5.37 89.44 8.95 840.12 17.84 28.87 219.96 16.87 mcypna 8.73 8.85 142.4 15.07 1332.12 27.19 45.25 352.73 28.59 1pen24m 0.97 1 14.4 1.79 112.79 2.89 4.52 32.78 4.3 benze 7.77 7.79 57 9.26 419.62 12.8 20.36 123.05 14.03 

6-7
cyhexa 2.38 2.42 35.48 4.22 291.39 7.98 10.31 90.55 7.39 

hexa2m 5.57 5.48 62 10.02 467.73 14.18 19.39 145.54 14.93 

pen23m 2.03 1.99 25.29 3.57 171.67 5.37 7.46 54.36 7.46 hexa3m 0.3 0.28 3.32 0.43 21.31 0.56 0.84 6.21 0.74 pa224m 2.19 2.1 23.45 3.75 173.5 5.21 7.13 55.49 4.76 

n_hept 4.25 4.49 45.47 8.45 278.39 10.66 13.79 103.51 11.51 mecyhx 4.67 4.72 47.99 8.5 308.14 10.56 14.49 105.3 12.11 pa234m 0.64 0.67 5.23 0.9 20.08 1.01 1.9 6.69 2.65 tolue 31.64 31.81 239.97 50.59 1093.91 54.95 69.39 419.54 70.68 4

hep2me 2.29 2.34 17.19 3.64 67.26 3.62 4.91 29.51 4.61 hep3me 2.6 2.58 17.28 3.86 65.21 3.8 5.51 29.53 5.03 n_oct 1.96 1.96 11.36 2.57 33.32 2.52 3.77 17.78 2.52 etbz 7.91 7.86 45.24 11.05 101.8 9.22 11.5 66.14 14.88 mp_xyl 28.39 28.07 152.26 39.78 328.81 31.72 38.56 229.84 52.43 3

styr 1.41 1.27 4.37 1.37 4.23 0.9 1.43 3.81 1.04 o_xyl 11.72 11.75 58.83 15.37 109.53 12.11 15.65 85.91 20.23 1

n_non 1.09 1.03 5.51 1.44 7.09 1.11 1.65 7.48 0.72 iprbz 0.69 0.66 3.48 0.81 4.19 0.76 0.82 4.34 1.09 n_prbz 2.7 2.62 11.77 3.06 12.85 2.38 3.05 14.76 4.03 m

_

etol 9.17 8.76 34.14 10.41 36.04 3.62 4.45 42.76 13.27 

p_etol 4.38 4.12 16.91 4.68 15.85 7.53 9.41 20.54 6.11 bz135m 4.32 4 14.92 4.61 13.89 3.53 4.4 18.18 5.98 

o_etol 4.11 3.95 12.9 4.5 14.29 3.51 5.09 16.69 5.57 bz124m 13.95 12.89 47.24 15.43 40.54 11.14 14.38 52.49 20.08 1

n_dec 1.97 2.27 1.72 0.39 1.73 1.18 1.36 3.26 0.46 bz123m 3.48 3.39 1.09 0.38 7.52 2.55 3.43 0.98 0.65 detbz1 0.99 1.04 2.25 0.78 1.92 0.74 1.54 2.98 1.09 detbz2 3.24 3.14 6.54 2.78 5.08 2.01 2.93 7.31 3.28 n_unde 1.47 1.51 3.53 1.4 2.1 1.05 1.83 3.3 1.11 tnmhc 656.76 646.78 8908.06 702 72023.3 1690.04 2706.57 21748.67 1976.27 106

6-8
6.3 Appendix C: Breath Samples 

Site Date Time CO2, bud13

% 

ethoh mtbe benze tolue etbz 

Refueling W/Vapor Recovery, PreFuel 4/29 1200 5.09 0.27 133.86 0.74 0.87 99.31 0.53 Refueling W/Vapor Recovery, PostFuel 4/29 1215 4.38 0.10 87.75 0.46 0.89 78.42 0.49 Garage, Pre 4/29 1642 5.91 0.21 78.10 0.46 0.81 72.49 0.46 Garage, Peak 4/29 1654 6.06 0.04 12.11 0.18 0.23 2.12 0.16 Garage, Post 4/29 1715 6.16 0.04 3.26 0.07 0.06 0.45 0.04 Freeway, Pre 4/29 731 5.35 0.20 51.26 0.27 0.70 137.39 0.72 Freeway, Peak 4/29 800 5.00 2.77 26.90 1.13 4.73 150.46 2.83 Freeway, Post 4/29 826 5.44 0.85 26.60 0.36 1.88 125.08 0.99 Refueling W/Vapor Recovery, PreFuel 4/30 1047 6.24 0.12 138.93 0.69 1.16 68.79 0.44 Refueling W/Vapor Recovery, PostFuel 4/30 1059 5.79 0.65 153.24 0.64 2.28 77.75 0.78 Refueling W/O Vapor Recovery, PreFuel 4/30 1203 4.93 0.18 54.35 0.40 1.01 50.46 0.44 Refueling W/O Vapor Recovery, PostFuel 4/30 1216 5.80 0.00 201.01 1.80 5.47 75.04 0.65 Garage, Pre 4/30 1643 6.11 1.35 137.30 0.32 1.87 60.47 0.62 Garage, Peak 4/30 1707 6.01 3.65 107.43 0.33 5.35 61.73 1.73 Garage, Post 4/30 1721 5.83 5.24 123.88 0.57 7.17 63.39 1.68 Freeway, Pre 4/30 727 5.64 0.15 86.91 0.48 0.64 87.07 0.57 Freeway, Peak 4/30 757 4.71 4.48 51.23 0.75 7.92 102.67 3.49 Freeway, Post 4/30 822 4.50 0.69 54.62 0.36 1.81 82.25 0.86 Refueling W/O Vapor Recovery, PreFuel 4/30 923 4.92 0.18 65.02 0.46 1.22 75.46 0.69 Refueling W/O Vapor Recovery, PostFuel 4/30 935 4.74 0.00 64.67 5.04 16.80 99.08 2.14 Refueling W/O Vapor Recovery, PreFuel 5/1 1107 6.71 0.05 103.18 0.35 0.97 2.72 0.15 

6-9
Refueling W/O Vapor Recovery, PostFuel 

5/1 1119

7.7

4

0.15 176.

98 1.2

2

2.7

6

4.98 0.2

7

Refueling W/Vapor Recovery, PreFuel 

5/1 12

2

7

6.0

2

0.11 118.30

0.6

9 1.2

7

2.63 0.15 

Refueling W/Vapor Recovery, PostFuel 

5/1 1238 5.21 0.21 81.0

7

0.55 1.14

2.61 0.18 

Garage, Pre 5/1 16

48 7.2

4

0.65 45.68 0.34 1.41 2.9

0

0.2

9

Garage, 

Peak 5/1 17

03 5.82 3.36 99.7

4

0.37 3.9

7 5.9

2

0.6

4 

Garage, 

P

ost 5/1 1719

6.30

0.75 60.61 0.33 1.7

9 3.43 0.28 

Freeway, Pre 5/1 712

6.33 0.0

7 36.68 0.2

4

0.2

9

0.6

4

0.0

4

Freeway, Peak 5/1 735 5.05 3.7

9 36.45 0.6

7

7.03 19.53 1.93 

Freeway, P

ost 5/1 80

2 5.35 3.58 23.50

0.4

6

6.14

23.4

7 1.57

Refueling W/Vapor Recovery, PreFuel 

5/2 1037

4.82

0.12

4

2.4

7

0.45 0.9

9 30.16

0.25 

Refueling W/Vapor Recovery, PostFuel 

5/2 1050 5.7

0

0.13 28.59

0.4

7 1.25 35.16

0.52 

Garage, Pre 5/2 16

45 5.25 0.93 7

2.4

2

0.0

0 1.32

2

9.85 0.34 

Garage, 

Peak 5/2 17

0

6 5.25 0.56

6

9.43 0.18 1.01 2

7.71 0.2

6

Garage, 

P

ost 5/2 1716

6.0

0 1.45 63.4

7

0.18 2.7

2 31.4

9

0.6

0 

Freeway, Pre 5/2

7

2

9 5.31 0.19 113.50

0.2

0

0.4

9 41.3

2

0.2

6

Freeway, Peak 5/2

7

4

9

4.93 1.9

6

6

6.01 0.35 3.65 4

6.59 1.14 

Freeway, P

ost 5/2 816

4.57

2.14 36.2

7

0.33 3.36 50.4

2

0.91 

Refueling W/O Vapor Recovery, PreFuel 

5/2

9

2

0 5.52

0.4

2

7

0.7

4

0.2

0

0.7

2 32.43 0.2

9

Refueling W/O Vapor Recovery, PostFuel 

5/2

932

6.0

9

0.0

0

6

4.88 5.15 16.0

7 62.3

4 1.30 

Refueling W/Vapor Recovery, PreFuel 

5/5 10

45 5.9

9

0.10 92.4

2 1.0

9

2.85 5.58 0.2

9

Refueling W/Vapor Recovery, PostFuel 

5/5 1058 5.59

0.05 33.13 0.86 3.52

7.34

0.36 

Freeway, Pre 5/5 7

4

4

0.98 0.0

6 17.6

2

0.2

7

0.31 0.53 0.05 

Freeway, Peak 5/5 755 5.89

2.03 17.71 0.48 2.93 4.80

0.50 

Freeway, P

ost 5/5 832 5.25 2.17 10.05 0.35 4.2

9 15.6

7 1.2

2 

Refueling W/O Vapor Recovery, PreFuel 

5/5 9

23 6.30

0.18 88.5

0

0.23 0.6

7 1.7

7

0.13 

Refueling W/O Vapor Recovery, Post- 5/5 936 6.

4

2

0.0

0 84.8

7 16.36 80.68 7

9.30

2.73 

6-10
Fuel 

Garage, Pre 5/6 1644 6.16 0.49 175.18 0.30 1.42 2.65 0.32 Garage, Peak 5/6 1706 5.59 1.37 102.34 0.22 1.97 3.93 0.55 Garage, Post 5/6 1718 6.48 0.65 58.69 0.27 1.57 3.05 0.34 

6-11
6.4 Appendix D: DNPH 

Site Date Start

time 

Stop 

time 

Duration V (L) Vu 

(L) 

formal formalu acetal acetalu aceto acetou

Freeway 4/29/03 0742 0822 40 47.1 2.36 17.38 0.95 5.27 0.80 32.18 1.85

Freeway 4/30/03 0739 0819 41 45.2 2.26 19.02 1.04 4.67 0.80 28.35 1.64

Freeway 5/1/03 0720 0800 41.1 45.3 2.27 19.80 1.07 8.22 0.95 57.34 3.24

Freeway 5/2/03 0735 0815 40 44.1 2.21 19.13 1.05 4.84 0.82 20.67 1.23

Freeway 5/5/03 0750 0830 40 44.1 2.21 17.56 0.97 5.24 0.83 61.17 3.45

Garage 4/29/03 1642 1712 30 33.0 1.65 5.59 0.43 2.83 0.99 34.36 2.01

Garage 4/30/03 1645 1715 30 33.0 1.65 7.58 0.52 3.50 1.01 27.38 1.63

Garage 5/1/03 1642 1717 30 33.0 1.65 9.12 0.58 3.76 1.01 20.23 1.27

Garage 5/2/03 1645 1715 30 33.1 1.66 7.35 0.49 2.76 0.99 21.77 1.35

Garage 5/6/03 1645 1715 30 33.1 1.66 5.44 0.42 2.50 0.98 44.91 2.58

Garage-Blank 5/2/03 1706 1706 0 30.6 1.53 0.00 0.23 1.85 0.27 1.68 0.19

Garage-Blank 5/6/03 1612 1612 0 30.6 1.53 0.00 0.23 0.43 0.21 0.87 0.17

Refueling W/O Vapor 4/30/03 0921 0941 19.9 21.9 1.10 3.62 0.52 3.37 1.47 13.31 1.12

Refueling W/O Vapor 4/30/03 1205 1225 20 22.0 1.10 2.12 0.46 2.57 1.46 10.66 1.03

Refueling W/O Vapor 5/5/03 1106 1126 20.4 22.4 1.12 5.52 0.55 2.72 1.43 31.06 1.92

Refueling W/O Vapor 5/2/03 0918 0938 20 22.0 1.10 4.03 0.53 3.26 1.46 5.98 0.89

Refueling W/O Vapor 5/5/03 0923 0943 20 22.0 1.10 5.52 0.56 3.17 1.46 20.10 1.40

Refueling W/Vapor

Re 

4/29/03 1200 1220 20 22.0 1.10 4.35 0.54 2.97 1.46 20.00 1.39

Refueling W/Vapor

Re 

5/1/03 1225 1245 21.3 23.4 1.17 3.29 0.49 1.77 1.36 10.01 0.96

Refueling W/Vapor 

Re 

4/30/03 1045 1105 20 22.0 1.10 2.87 0.47 1.38 1.44 12.90 1.11

Refueling W/Vapor

Re 

5/2/03 1036 1056 20 22.0 1.10 4.67 0.54 2.47 1.46 9.07 0.97

Refueling W/Vapor

Re 

5/5/03 1045 1105 20 22.0 1.10 3.29 0.52 1.78 1.44 7.94 0.95

formal =Formaldehyde acetal = Acetaldehyde 

formalu =Formaldehyde uncertainty acetalu =Acetaldehyde uncertainty 

aceto=Acetone

acetou=Acetone uncertainty 

6-12