PM science and regional haze
Excessive levels of suspended particle are measured in many urban areas throughout the world. The U.S. EPA has promulgated new ambient air quality standards for PM2.5 and PM10 (particles with aerodynamic diameters less than 10 and 2.5 microns, respectively). The new PM10 standards are less stringent than the prior standards, setting targets of 3-year average 98th percentiles for 24-hour PM2.5 averages, 99th percentiles for 24-hour PM10 averages, and three-year averages in place of annual averages. This means that infrequent events, such as fires or industrial upsets, will not greatly influence compliance status. The acceptable PM2.5 levels are strict for the annual average at 15 {micro}g/m{sup 3}, but compliance will be determined by a spatial average from several monitors rather than for a single monitor. Carbon, ammonium, sulfate, and nitrate are the major PM2.5 components in most areas, with geological material constituting only 5% to 15% of the mass. Chemical concentrations in the PM2.5 size fraction are also the major cause of urban and regional haze. This haze results from both the scattering and absorption of light by small particles. PM2.5 will use only population-oriented monitors to determine attainment, and ``fence line'' sites located to determine maximum impact from a facility will not be used to determine compliance as they have been in the past. Primary particles and precursor gases from fuel combustion in vehicles, homes, and industries will become the pollutants under greatest scrutiny in non-attainment areas.
- Research Organization:
- Desert Research Inst., Reno, NV (US)
- OSTI ID:
- 20082303
- Resource Relation:
- Conference: Sixteenth Annual International Pittsburgh Coal Conference, Pittsburgh, PA (US), 10/11/1999--10/15/1999; Other Information: 1 CD-ROM. Operating systems required: Windows 95/98; Windows 3.X, Macintosh; PBD: 1999; Related Information: In: Sixteenth annual international Pittsburgh Coal Conference: Proceedings, [2000] pages.
- Country of Publication:
- United States
- Language:
- English
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