Impact/Purpose:

The overall goal of human exposure research in air toxics is to develop the methods, data, and models of exposure that will provide the scientific basis for EPA to move to a risk-based program and that will enhance NATA. Specific objectives for this measurement task are to:

o Characterize exposure concentrations and variability in critical microenvironments using targeted measurement studies;

o Quantify the relationship of personal exposure to ambient and indoor concentrations;

o Identify critical microenvironments, human activities, and factors influencing exposure to air toxics;

o Develop methods to quantify exposure from background, point or area sources, and microenvironmental sources;

o Evaluate aggregate and cumulative exposures.

Description:

EPA's air toxics program is moving toward a risk-based focus. The framework for such a focus was laid out in the National Air Toxics Program: Integrated Urban Strategy which included the requirement for EPA to conduct a National-Scale Air Toxics Assessment (NATA) of human exposure to hazardous air pollutants (HAPs). There are currently large knowledge gaps that limit the NATA approach for estimating human exposure. Thus, if NATA is to be useful as an indicator of exposure and, hence, risk, rather than simply a measure of relative ambient concentrations, substantial research is required. NERL's Air Toxics research in human exposures will develop the methods, data, and models of human exposure that will provide the scientific basis for EPA to move to a risk-based program and that will enhance NATA. This research will provide the critical link between ambient concentration measurements and risk assessment.

The overall approach to developing our human exposure research program is to integrate models and measurements in an iterative process. Current data are compiled into existing models to generate exposure estimates for various population groups. These results are then used to identify data gaps and develop a measurements research plan. Exposure assessments conducted for NATA are a critical part of this preliminary work. The data gathering activities include discussions and meetings with other organizations to gain an understanding of current efforts and to identify opportunities for leveraging resources. Existing data has been compiled and data gaps identified. A peer-reviewed air toxics research plan combining exposure measurements and modeling efforts was produced in FY02. In FY03, targeted air toxics methods development for acrolein and 1,3-butadiene identified in the research plan were initiated and will continue in FY04. Field studies conducted under this task will be combined with field studies being conducted under the PM (Causal Agents) Task 6387 due to the collaborative nature of the two programs and as a way to leverage funding.

Record Details:

Record Type:PROJECT

Start Date:10/01/2001

Completion Date:09/01/2004

Record ID: 56207

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Project Information:

Progress :During FY01 and FY02, discussions/meetings were held with OTAQ, OAQPS, ORIA, NCEA, and NHEERL to identify data needs. In addition to discussions, a series of air toxics monitoring studies were initiated to develop exposure monitoring methods and data needed to investigate potential human exposures to selected air toxics. Studies supported in part by FY01 air toxics funding included the COPP Study (Car-related Occupational Particulate Matter and Related Air Toxics Exposure to Patrol Troopers) which involved in-vehicle, roadside, and community-based measurements of air toxics associated with automotive emissions; a study to evaluate field collection methodologies to reduce personal monitoring burden, reduce uncertainties in PM mass carbon speciation, and reduce artifact interferences related to sample collections for mass spectrometric-based elemental analyses (ICP-MS). Efforts funded in whole or part by this air toxics task in FY02 included the development of a passive aldehyde and ketone sampler (PAKS) utilizing dansylhydrazine (DNSH) for the collection and analysis of acrolein; collection and analysis of the air toxics components for the Tampa Asthmatic Children's Study (TACS) conducted October/November 2002, in Tampa, FL; and the PM/Air Toxics study (Detroit Exposure Aerosol Research Study, DEARS) scheduled to be conducted beginning in FY04 and continuing in FY06. During FY02, a Joint Research Plan for US EPA/NERL Air Toxics Human Exposure Measurement and Modeling Programs,was prepared. This research plan satisfied the requirements for APMs 26 (Task 9523) and 219 (Task 9524) and will serve as the guide for air toxics human exposure research under this task. During FY03, development of the PAKS method for acrolein and other aldehydes and ketones was continued and the development of a passive method for 1,3-butadiene and other volatile organic compounds (VOCs) was initiated. These methods will be utilized in the combined PM/Air Toxics study - DEARS (Tasks 9523 and 6387). The study design for DEARS was written and peer reviewed during FY03.

Relevance :Work on the task will provide the data and tools that will allow EPA to move its air toxics program to a risk-based focus. The development of data and the evaluation of exposure factors will provide valuable input for human exposure models, and reduce the reliance on default assumptions in the risk assessments. This information will improve NATA as well as other exposures conducted for air toxics. It will directly support GPRA Sub-Obective 1.2.1 to "develop and improve the scientific information and tools for quantitative assessment of nationwide, urban, and residual air toxics risks to susceptible populations from hazardous air pollutants considering both indoor and ambient air environments. Our research study plan will identify and address critical data needs for enhancing the NATA. Results from the above cited studies will help provide a basis for design and implementation for additional studies.

Clients :EPA/OAQPS (point of contact - Ted Palma) in support of NATA assessments, EPA/OTAQ ( point of contact - Rich Cook) , EPA NCEA (point of contact - Chon Shoaf), EPA/NHEERL (point of contact - Will Boyes), states, scientific community

Project IDs:

ID Code :9523

Project type :OMIS