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HEASD PM EXPOSURE FACTORS- IMPROVE UNDERSTANDING OF THE FACTORS WHICH DETERMINE HUMANS' EXPOSURE TO PARTICLES SMALLER THAN 2.5 MICRONS
Impact/Purpose:
The objective of this task is to develop and employ PM measuring tools for EPA researchers and regulators to use to characterize the exposure of humans to PM of outdoor origin in both outdoor and indoor environments. Achieving these objectives will improve the scientific foundation for risk assessments of PM in future reevaluations of the NAAQS and in assessing exposure of humans to PM.
Description:
In July 1997, the EPA Administrator issued a new Particulate Matter (PM-2.5) National Ambient Air Quality Standards (NAAQS) that had been developed largely on the basis of epidemiological studies. These studies found a consistent association between ambient PM concentrations and various adverse health effects. Because PM is a complex mixture of chemically diverse materials, there are many unanswered questions about the physical and chemical properties of the particles that are causing the adverse health effects; the sources of these particles; and the true human exposure to these particles and co-pollutants (e.g., sulfur dioxide, carbon monoxide, ozone, and nitrogen dioxide) which may also influence effects. The PM exposure process is a dynamic one and is very dependent on the environments the individual encounters and the activities done therein. Although most individuals in the U.S. spend 90% of their time in buildings and other confined environments (e.g., cars), even while indoors they can receive exposure to particles that were formed outdoors. This task seeks to identify those physical parameters (factors) that determine: (1) the contribution that particles formed outdoors make to the particle concentrations encountered indoors; and (2) an individual's actual total exposure to PM.