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Research Priorities for Airborne Particulate Matter: • III •
RESEARCH TOPIC 1. OUTDOOR MEASURES VERSUS ACTUAL HUMAN EXPOSURES
What are the quantitative relationships between concentrations ofparticulate matter and gaseous copollutants measured at stationary outdoorair-monitoring sites and the contributions of these concentrations toactualpersonal exposures, especially for subpopulations and individuals?
In its first report (NRC 1998), the committee recommended that information be obtained on relationships between total personal exposures and outdoor concentrations of PM. Specifically, the committee recommended longitudinal panel studies, in which groups of 10-40 persons would be studied at successive times to examine the relationship between their exposures to PM and the corresponding outdoor concentrations. The studies were intended to focus not only on the general population, but also on subpopulations that could be susceptible1 to the effects of PM exposures, such as the elderly, children, and persons with respiratory or cardiovascular disease. It was recommended that some of the exposure studies include measurements of PM with an aerodynamic diameter of 2.5 µm or less (PM2.5), PM with an aerodynamic diameter of 10 µm or less (PM10), and gaseous copollutants. It was expected that the investigations would quantify the contribution of outdoor sources to personal and indoor exposures. The design and execution of studies were to take about 3 years, and the suggestion was made to conduct the studies at various geographical locations in different seasons.
Research Progress and Status
Substantial research is in progress, and some studies, started before the committee's first report, have been completed. Results of
The committee is aware that there are several definitions of “susceptibility” (Parkin and Balbus 2000). in using the term in this report, the committee refers to an increased risk at a particular exposure that is greater for susceptible people than for healthy people.