The Aerosol Research and Inhalation Epidemiology Study (ARIES): PM2.5 massand aerosol component concentrations and sampler intercomparisons

The Aerosol Research and Inhalation Epidemiology Study (ARIES) was designed to provide high-quality measurements of PM2.5 its components, and co-varyi ng pollutants for an air pollution epidemiology study in Atlanta, GA. Air pollution epidemiology studies have typically relied on available data on particle mass often collected using filter-based methods. Filter-based P M2.5 sampling:is susceptible to both positive and negative errors in the me asurement of aerosol mass and particle-phase component concentrations in th e undisturbed atmosphere. These biases are introduced by collection of gas- phase aerosol components on the filter media or by volatilization of partic le phase components from collected particles. As part of the ARIES, we coll ected daily 24-hr PM2.5 mass and speciation samples and continuous PM2.5 da ta at a mixed residential-light industrial site in Atlanta. These data faci litate analysis of the effects of a wide variety of factors on sampler perf ormance. We assess the relative importance of PM2.5 components and consider associations and potential mechanistic linkages of PM2.5 mass concentratio ns with several PM2.5 components. For the 12 months of validated data collected to date (August 1, 1998-July 31, 1999), the monthly average Federal Reference Method (FRM) PM2.5 mass al ways exceeded the proposed annual average standard (12-month average = 20.3 =/- 9.5 mu g/m(3)). The particulate SO42- fraction (as (NH4)(2)SO4) was la rgest in the summer and exceeded 50% of the FRM mass. The contribution of ( NH4)(2)SO4 to FRM PM2.5 mass dropped to less than 30% in winter. Particulat e NO3- collected on a denuded nylon filter averaged 1.1 +/- 0.9 mu g/m(3). Particle-phase organic compounds las organic carbon x 1.4) measured on a de nuded quartz filter sampler averaged 6.4 +/- 3.1 mu g/m(3) (32% of FRM PM2. 5 mass) with less seasonal variability than SO42-.