Citation:

Kim, C. Health Risk of Exposure to Atmospheric Pollutant Particles. Presented at International Aerosol Conference, Busan, SOUTH KOREA, August 28 - September 02, 2014.

Impact/Purpose:

Exposure-dose relationship is essential information in health risk assessment because what eventually leads to biological effects is the dose of pollutant PM at the site of internal organ of the body. Estimating the dose is difficult, particularly for multi-component mixtures. New approach to determine the dose for size-fractioned PM will help to improve exposure-dose relationships of complex atmospheric PM.

Description:

In relation to multi-component mixture nature of atmospheric PM, this presentation will discuss methods for estimating the respiratory internal dose by experiment and mathematical modeling, limitations of each method and interpretations of the results in the context of health risk assessmnt. Particulate matter (PM) in the atmosphere is known to cause increased morbidity and mortality. An increase in hospital admissions on high PM days is well- documented particularly in children and elderly subjects for respiratory and cardiopulmonary events. A small but significant increase in PM-associated mortality, presumably among susceptible populations, has been reported consistently throughout different regions and cities. However, specific attributes of PM that may cause health effects are somewhat ambiguous and by what mechanisms and processes such effects may take place are yet to be fully understood. PM is a complex mixture of particles with different sizes and chemical compositions. Size distribution is quite broad, but generally is expressed by bimodal forms composed with fine and coarse PM. Sources of the fine and coarse PM are different, the former mainly from combustion of fossil fuels and the latter from mechanical abrasion and wind-blown road and ground dust. Consequently, chemical compositions vary reflecting sources. Some of these characteristics are further influence by geographical regions and seasons. The accurate data for PM characteristics provides the foundation of exposure analysis. In assessing health risk, exposure-dose relationship is essential information because what eventually leads to biological effects is the dose of pollutant PM at the site of internal organ of the body. The internal dose is determined primarily by three factors; ambient PM characteristics,personal inhalation pattern and respiratory tract anatomy. Because the latter two human factors are difficult to assess in the field study, dose estimate is largely ignored in the epidemiology studies and is performed only in the laboratory under controlled exposure conditions. Typically, dose estimates are performed based on monodispersed aerosols. As chemical speciation data has become available for size- fractionated fine (PM2.5) and coarse (PM10-2.5) PM samples, this allows us to analyze the size specific dose not only for physical metrics (particle size, surface area and number) but also for chemical components.

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