Recent Research Conducted by TRJ Environmental Relevant to

Estimating Exposures to Air Toxics

Ted Johnson

TRJ Environmental, Inc.

Chapel Hill, NC

EPA Exposure Models

• HAPEM4/NATA: assisted in design and application of HAPEM4 exposure module for the National Air Toxics Assessment (NATA).

• APEX: assisted in design and testing of APEX probabilistic exposure models for CO and ozone, including use of Monte Carlo models to develop special input data sets.

• SimExpo: development of SimExpo-HAP exposure model and application to benzene.

Sample Output of SimRisk Showing 95th Percentile of Lifetime Exposure

vs. Distance for Nine Styrene Facilities

95th Percentile of Average Lifetime Concentration - Styrene - Nine Facilities

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Distance, m

Sty

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3) XMLO

XMMD

XMHI

CMLO

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CMHI

MMLO

MMMD

MMHI

Sample Output of SimExpo-Ozone

Diurnal Pattern of Ambient Conc, Exposure Conc, and VE

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Minute Index

Ambient Conc

Expo Conc

VE

VE x Expo Conc/10

Field Studies Measuring Personal and Microenvironmental Concentrations of Air Toxics

• Baltimore Multi-Pollutant Study: 11 pollutants (including benzene) measured by (1) technician following script and (2) 20 retiree volunteers – unscripted.

• Sacramento/Milwaukee Aldehyde Studies: 16 pollutants (including aldehydes and BTEX) measured by (1) technician following script and (2) 38 volunteers – unscripted.

• Section 211b Exposure Study: microenvironmental concentrations of hazardous air pollutants from motor vehicle evaporative and combustion emissions were measured under varying conditions related to the use of MTBE and oxyfuels. Sampled ME’s included trailing vehicles, garages, service stations, underground parking lots, and other potentially high-exposure locations.

Field Studies Providing Other Data Useful in Modeling Microenvironments

• Columbus Scripted House Study: measured air exchange rates and benzene indoor/outdoor ratios under scripted ventilation scenarios in test house.

• Vehicle Window Studies: camcorder surveys of factors affecting vehicle window position in Houston and central NC.

• Residential Windows Study: visual survey of factors affecting open windows and doors in Durham NC residences.

Chapel Hill Vehicle Windows Study Video Camera and Meteorological Measurements

Methods for Estimating Breathing Rates

• VE Estimator: menu-driven program for (1) sequencing time/activity data of specified demographic groups and (2) estimating ventilation (Ve) rates by event. Funded by EPA-NCEA.

• Sensitivity Analyses of VE Predictors: evaluated relative effects of MET value, basal metabolic rate, VO2max, VE/VO2 ratio, age, weight, gender, and other factors on VE values estimated by APEX and pNEM models. Compared VE estimates with empirical data.

• In-Depth Literature Review: children’s time/activity patterns. Focused on statistics and databases available for characterizing outdoor high-exertion activities.

Compendiums of Modeling Algorithms, Distributions, and Databases

• Guide to EPA exposure models: 600-page “Guide to Selected Algorithms, Distributions, and Databases Used in OAQPS Exposure Models” prepared by Johnson (project lead = EOHSI, funded by EPA STAR Grant).

• DIMES: menu-driven database listing microenvironment factors for air toxics (project lead = EOHSI, funded by ACC).

Time/Activity Patterns and Residential Occupancy Periods

• Residential Occupancy Periods: development of improved method for estimating total time spent in current residence (based on 1992 Johnson-Capel Monte Carlo method).

• PFILES: on-going development of low-burden methods for collecting longitudinal time-activity data (project lead = RTI International, funded by EPA STAR Grant).

• Pilot Test of Still Camera/GPS Diary: technician carried GPS and digital camera taking photos at one-minute intervals.

• Pilot Test of Ozone Monitor/Camcorder System: technician carried continuous ozone monitor, camcorder, GPS, weather meter, heart rate monitor, and accelerometer.

PFILES Pocket PC Diary

PFILES Audio Diary

PFILES Product Use Monitor (FOB) and Positional Beacon

Continuous Personal Ozone Monitoring with Wide-Angle Camcorder, GPS,

and Actiheart (heart rate and accelerometer)

                                               

                                

Fully-outfitted technician

Actiheart Monitor

Activity and Heart Rate Data

Selected Research Projects of Special Relevance

Field Studies Measuring Personal and/or Microenvironmental Concentrations of Air Toxics

Baltimore Multi-Pollutant Study

• Funding: EPRI and API.

• Team: Harvard and TRJ Environmental

• Period: Summer 1998 - Winter 1999

• Location: Baltimore, MD

• Two-Part Study– Scripted activities– Personal monitoring of volunteers

Baltimore Multi-Pollutant Study: Scripted Activity Phase

• Technician used roll-around cart to measure 11 pollutants (including PM2.5, ozone, CO, benzene) in ME’s specified by prepared scripts. 1 h/12 h periods.

• Supplemental data obtained from activity diary carried by technician, fixed-site monitoring sites, and meteorological stations.

Baltimore Multi-Pollutant Study: Scripted Phase Results

• Detailed results in journal articles prepared by Harvard team and by TRJ (Johnson, Long, and Ollison, JEAEE, No. 10, 403 - 411).

• SLR analyses performed by TRJ indicated that PM2.5 exposures were affected by passive smoking, high ambient PM2.5

concentrations, food preparation, charcoal grills, car travel, outdoor roadside locations, and high humidity.

Baltimore Multi-Pollutant Study: Personal Monitoring Phase

• A panel of 20 volunteer retirees carried personal monitors (PM2.5, ozone, VOC’s, etc.) and real-time diaries for nominal 24-h sampling periods as they engaged in normal daily activities.

• Summer 1998: 168 subject-days.

• Winter 1999: 165 subject-days.

Baltimore Multi-Pollutant Study: Personal Monitoring Results

• Detailed results in journal articles prepared by Harvard team and by TRJ (Johnson, Long, and Ollison, JEAEE, No. 10, 403-411).

• TRJ developed a simplified PM2.5 exposure model based on SLR analyses (R2 = 0.77) of scripted-phase ME data and applied it to eight subject-days of activity data provided by personal monitoring study. Absolute differences between model estimates and measured 24-hour exposures averaged 13 percent. Fixed-site monitors provided poor estimates of exposure (19% < absolute difference < 27%).

Sacramento/Milwaukee Aldehyde Study

• Funding: EPA Star Grant• Team: RTI and TRJ Environmental• Period: Summers 1999 and 2000• Locations: Sacramento and Milwaukee• Two-Phase Study

– Scripted activities– Personal monitoring of volunteers

Sacramento/Milwaukee Aldehyde Study: Scripted Phase

• Technician used roll-around cart to measure 16 pollutants (8 aldehydes, 7 VOC’s, and CO) in ME’s specified by prepared scripts.

• Supplemental data obtained from GPS and activity diary carried by technician, fixed-site monitors, and meteorological instruments.

• Over 380 1-hr script periods in database.

Sacramento/Milwaukee Aldehyde Study: Scripted Phase Results

• Detailed results in project report and journal articles.

• Extensive SLR analyses were performed by TRJ to evaluate the predictive power of co-measured pollutants, ambient concentrations, met parameters, microenvironment, proximity to specific sources, geographic location, activity, and special conditions (e.g., forest fires). Many R2 values exceeded 0.9.

Sacramento/Milwaukee Aldehyde Study: Personal Monitoring Phase

• A panel of 38 volunteers in each city carried aldehyde monitors and real-time diaries for nominal 24-h sampling periods as they engaged in normal daily activities.

• Two questionnaires provide background and monitoring period information.

• Indoor/outdoor pollutant concentrations and air exchange rates were measured in each home.

Sacramento/Milwaukee Aldehyde Study: Personal Monitoring Results

• Detailed results in project report and journal articles.

• Extensive SLR analyses were performed by TRJ to evaluate the predictive power of indoor, outdoor, and fixed-site concentrations; met parameters; microenvironment; proximity to specific sources; geographic location; activity; and occupation. Several R2 values exceeded 0.9.

Sacramento/Milwaukee Aldehyde Study: Modeled vs. Measured Exposures

• Using scripted ME results and measured indoor/outdoor residential concentrations, TRJ developed a simplified exposure model based on time spent in each ME and applied it to the activity data provided by subjects of the personal monitoring study.

• Measured exposures were better predicted by this exposure model than by pollutant concentrations measured indoors and outdoors at residence.

Columbus Scripted House Study

• Funding: ACC and API

• Team: Battelle and TRJ Environmental

• Period: January - February 2002

• Location: Columbus, Ohio

Columbus Scripted House Study: Test Residence

Columbus Scripted House Study: Procedures

• Ventilation conditions in an occupied house were varied hourly according to a prepared script over a three-day period.

• Data included hourly values for air exchange rate, indoor and outdoor concentrations of six pollutants (benzene, formaldehyde, PAH, CO, NO, and NOx), and met parameters.

Columbus Scripted House Study: Air Exchange Rates

• Air exchange rate increased with number of open windows and doors.

• All windows/doors closed (n = 39) – GM = 0.77 h-1

– GSD = 1.435• One or more windows/doors open (n = 27)

– GM = 1.98 h-1

– GSD = 1.902

Columbus Scripted House Study: Indoor Pollutant Concentrations

• SLR analyses identified the following “best” predictors of indoor concentrations: – outdoor pollutant concentration– indoor pollutant concentration during

preceding hour • Other important predictors: AER, number

and location of apertures, wind speed, AC operation, indoor temp, outdoor temp, and relative humidity (depending on pollutant).

Section 211b Exposure Study

• Funding: consortium of affected industries. • Team: Desert Research Institute, Lovelace

Labs, Southwest Research Institute, and TRJ Environmental.

• Reno Pilot Study: Feb/March 2002• High-end exposure studies: Houston, Atlanta,

and Chicago; Summer/Winter 2003• Trailing Vehicle and Residential Garage

Studies: San Antonio, Summer/Winter 2003

Section 211b Exposure Study: Principal Goals of Study

• Quantify personal exposures to motor vehicle evaporative and combustion emissions in ME’s representing upper end of exposure frequency distributions.

• Relate ME concentrations to fixed-site measurements.

• Evaluate the effects of MTBE and oxyfuels on personal exposures.

Section 211b Exposure Study: Microenvironmental Exposure Studies

• Technicians used state-of-the-art equipment on roll-around cart and in mobile laboratory to measure pollutant concentrations in potential high-end ME’s according to prepared daily scripts (continuous and integrated one-hr data).

• Biomarker samples (urine and breath) were collected for selected ME’s.

Monitoring System in Mobile Van