Impact/Purpose:

The primary objectives are:

1) to complete the validation and development of exposure databases resulting from the NERL PM panel studies (data produced under TDs 5676 and 3937),

2) to perform analyses on these databases and identify key factors that have the potential of influencing human exposures to PM constituents, and

3) to summarize and report the findings of these additional analyses.

Description:

An association has been demonstrated between ambient particulate matter (PM 2.5 and PM 10) concentrations and human morbidity/mortality. However, little is known regarding the most important sources of PM exposure, interpersonal and intrapersonal variability in exposure, and the relationship between personal exposure and ambient exposure estimates based on central site monitoring. The NERL in association with a series of cooperating universities is currently analyzing data from several recent longitudinal panel studies to address these uncertainties and to evaluate the important determinants of PM exposure for different subpopulations, area of the country, air sheds, housing structures, and life styles. Under this task, additional analyses will be performed using the data collected previously under tasks 5676 and 3937.

Record Details:

Record Type:PROJECT

Start Date:09/01/2003

Completion Date:09/01/2004

Record ID: 83315

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Project Information:

Progress :Longitudinal PM Exposure Studies have been conducted in eight east and west coast US cities (Boston, MA; Los Angeles, CA; Baltimore, MD; Research Triangle Park, NC; Seattle, WA; Fresno, CA; New York, NY; and Atlanta, GA) over several seasons. This range of studies is being used to investigate the influence of aerosol properties from different air sheds and seasons. Study participants were monitored over 7-28 days to investigate longitudinal correlations among personal, indoor, outdoor, and ambient community measurements. The studies included several susceptible subpopulations including the elderly and individuals with cardiovascular disease, COPD, and asthma. Collectively, these studies generated data from more that 200 people and their residences over 2,500 sampling days. More than 15,000 individual PM mass concentration measurements were collected along with an equivalent amount of time-activity pattern and PM source data. Data on PM mass, select PM species, and co-pollutants have been summarized and published in numerous peer reviewed journal articles. In addition, two key APM reports (NERL-PM-APM1, NERL-PM-APM21) and two supplemental interim milestone technical reports have been completed. Numerous technical presentations have been made at scientific conferences during 2000-2004.

Relevance :The work being conducted under this task directly responds to the NRC Research Topic 1: Outdoor Measures versus Actual Human Exposure, "What are the quantitative relationships between concentrations of particulate-matter and gaseous copollutants measured at stationary outdoor air monitoring sites, and the contributions of these concentrations to actual personal exposures, especially for potentially susceptible subpopulations and individuals?" (NRC, 1998). The studies were enhanced to provide data on chemical species of PM and copollutants. These studies are highly significant because an understanding of the relationship between the ambient PM2.5 mass data and personal PM exposure is, by most measures, fundamental to the credibility of the EPA regulatory program. The association between ambient PM concentrations and health outcomes in the population, despite the fact that people spend more time indoors than out, raises questions regarding exposure-response relationships. The issue is especially important for potentially susceptible subpopulations, who may well spend even more time indoors, or who may otherwise alter their exposures by their behaviors. Likewise, many factors may alter exposure by virtue of geographical setting, climate, building construction etc. and it is important to gain a fundamental understanding how these many factors interplay in defining individual exposures. With regard to protecting the most susceptible subgroups, it appears from the limited studies to date, that it is unlikely that disease state plays a major role in determining total personal exposure to PM of ambient origin - specifically the PM2.5 fraction. However, the individual time activity profiles, housing and other environmental factors would appear to have more significant influence on personal exposure. East coast and west coast seasonality differences may indicate significant influences of climate upon potential personal exposures. The role of specific PM constituents that may be responsible for the associations between ambient PM mass concentrations and epidemiological health effects has yet to be defined. It is therefore even more important to understand the ability of community-based measurements to accurately reflect exposures to the population and the factors that are influencing these exposures.

Clients :EPA/ORD/NHEERL ( John Creason), EPA/NCEA -(Les Grant) for criteria document review, EPA/OAQPS (John Bachmann/Ted Palma), EPA/OTAQ (Rich Baldauf), National Research Council, Scientific community

Project IDs:

ID Code :19540

Project type :OMIS