title: Effects of SO2 and NOx emission reductions on PM2.5 mass concentrations in the southeastern United States.
abstract: Measurements from sites of the Southeastern Aerosol Research and Characterization (SEARCH) program, made from 1998 to 2001, are used with a thermodynamic equilibrium model, Simulating Composition of Atmospheric Particles at Equilbrium (SCAPE2), to extend an earlier investigation of the responses of fine particulate nitrate (NO3-) and fine particulate matter (PM2.5) mass concentrations to changes in concentrations of nitric acid (HNO3) and sulfate (SO42-). The responses were determined for a projected range of variations of SO42- and HNO3 concentrations resulting from adopted and proposed regulatory initiatives. The predicted PM2.5 mass concentration decreases averaged 1.8-3.9 microg/m3 for SO42- decreases of 46-63% from current concentrations. Combining the S042- decrease with a 40% HNO3 decrease from current concentrations (approximating expected mobile-source oxides of nitrogen [NOx] reductions by 2020) yielded additional incremental reductions of mean predicted PM2.5 mass concentration of 0.2 microg/m3 for three nonurban sites and 0.8-1 microg/m3 for one nonurban and two urban sites. Increasing the HNO3 reduction to 55% (an estimate of adding Clear Skies Phase II NOx reductions) yielded additional incremental reductions of mean predicted PM2.5 mass concentration of 0-0.4 microg/m3. Because of the well-documented losses of particulate NO3- from Federal Reference Method (FRM) filters, only a fraction of these incremental changes would be observed.
authors.affiliation: Envair, Albany, CA, USA. cbenvair@pacbell.net
authors.forename: Charles L
authors.initials: CL
authors.lastname: Blanchard
authors.forename: George M
authors.initials: GM
authors.lastname: Hidy
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution / Q000517:prevention & control; D002947:Cities; D004784:Environmental Monitoring; D009589:Nitrogen Oxides / Q000032:analysis*; D010316:Particle Size; D015144:Southeastern United States; D013458:Sulfur Dioxide / Q000032:analysis* / Q000737:chemistry; D013816:Thermodynamics
chemical_list: D000393:Air Pollutants; D009589:Nitrogen Oxides; D013458:Sulfur Dioxide