NARSTO_EPA_SS_LOS_ANGELES_PARTISOL_DATA is the North American Research Strategy for Tropospheric Ozone (NARSTO) Environmental Protection Agency (EPA) Supersite (SS) Los Angeles Particulate Matter (PM) 2.5-10 Composition and Mass Data product. Data was collected using Partisol Model 2025-D samplers between late 2000 and late 2003 from sites at Downey, Claremont, Riverside, Rubidoux, and the University of Southern California (USC). Samples were collected episodically, frequently for a 24-hour per period, but in some cases multiple samples were collected over the course of a day. Element/metals, nitrate/sulfate ion, and mass concentration data were obtained. The Partisol is a dichotomous sequential multi-filter air sampler. It uses a virtual impactor to divide the air stream to facilitate the collection of fine (0.0-2.5um) and coarse (2.5-10.0um) particles onto a filter media over a pre-programmed collection period. The coarse fraction was analyzed using X-ray fluorescence and mass concentration analysis. Ion chromatography and mass concentration analyses were performed on the fine fraction. The overall objective of the Southern California Supersite (SCS) was to conduct research and monitoring that contributed to a better understanding of the measurement, sources, size distribution, chemical composition, physical state, spatial and temporal variability, and health effects of suspended PM in the Los Angeles Basin (LAB). Intensive aerosol measurements, well beyond the traditional PM2.5 mass, sulfate and nitrate concentrations, were conducted in several areas of the LAB. These included particle number concentrations, size distributions, and detailed PM chemical composition as a function of particle size. Sampling locations were chosen to provide wide geographical and seasonal coverage, including urban source sites and downwind receptor sites.

The primary sampling facility, a mobile Particle Instrumentation Unit (PIU), was deployed to several locations to conduct a wide range of PM measurements. Sampling in each site lasted for 6-12 months. Intensive PM measurements were also conducted up and downwind of several freeways of the LAB, to characterize near-roadway exposure environments and to support several in vivo and in vitro health studies. The monitoring activities of the SCS were linked with toxicology studies in the LAB using a mobile PM Concentrator facility to investigate health effects associated with exposures to ultrafine, fine and coarse particles. Finally, the PIU facility was successfully used as a platform to develop, test, and evaluate numerous PM measurement instruments and sampling technologies, including several monitors for semi-continuous size fractionated mass and chemistry, personal PM exposure monitors, particle concentration technologies, and particle counting devices.

NARSTO, which has since disbanded, was a public/private partnership, whose membership spanned across government, utilities, industry, and academe throughout Mexico, the United States, and Canada. The primary mission was to coordinate and enhance policy-relevant scientific research and assessment of tropospheric pollution behavior; activities provide input for science-based decision-making and determination of workable, efficient, and effective strategies for local and regional air-pollution management. Data products from local, regional, and international monitoring and research programs are still available.