Exposure and health risk considerations in setting new U.S. particulate standards
- Environ Corp., Emeryville, CA (United States)
In November 1996, the US Environmental Protection Agency (USEPA) proposed to modify US national ambient air quality standards (NAAQS) for particulate matter (PM). Two current standards directed at particulates 10 microns and smaller (PM{sub 10}) have been established: an annual standard of 50 {micro}g/m{sup 3} and a 24-hour standard of 150 {micro}g/m{sup 3}. USEPA has proposed to retain the current PM{sub 10} annual standard, and is considering maintaining a 24-hour standard at the same level as currently, but based on a 3-year average of the 98th percentile concentration measured at the highest monitor. USEPA has also proposed adding two new standards directed at fine particulates (2.5 microns and smaller), including an annual standard of 15 {micro}g/m{sup 3} (arithmetic mean averaged over 3 years, but spatially averaged over a set of monitors) and a 24-hour standard of 50 {micro}g/m{sup 3} (98th percentile concentration averaged over 3 years, based on the highest monitor). This paper discusses exposure and health risk considerations that enter into PM standard setting and implementation control strategy design, particularly pertaining to the characterization of uncertainty and its decision implications. First, results of PM exposure analyses are presented that use microenvironmental indoor air quality modeling to address indoor-outdoor concentration differences and the role of indoor sources. Observations are made regarding the contribution of outdoor-generated PM to total personal exposure and thus the effectiveness of controls implemented to attain a PM ambient standard. Second, results of a Monte Carlo PM health risk assessment are presented, using a methodology that, while similar to the one employed by USEPA in its risk assessment, is more fully probabilistic in its treatment of uncertainty. Third, results of a prototype decision analysis approach designed to aid standard setting in the face of uncertainty about PM-health effect causality and the identity of causative agent(s) are described.
- OSTI ID:
- 353487
- Report Number(s):
- CONF-970677--
- Country of Publication:
- United States
- Language:
- English
Similar Records
PM science and regional haze
Air quality standards must protect public health