The NARSTO_EPA_SS_HOUSTON_NH3_HNO3_is the North American Research Strategy for Tropospheric Ozone (NARSTO) Environmental Protection Agency (EPA) Supersite (SS) Houston, Ammonia and Nitric Acid Data product. It contains 24-hour integrated measurements of ammonia and nitric acid collected during September 30, 2000 through May 22, 2001 at the Houston Regional Monitoring (HRM) Site 3, Aldine, and Deer Park Houston Supersite monitoring locations. Samples were collected using a coated annular diffusion denuder downstream of a Teflon filter and analyzed by ion chromatography. Data set change history: Measurements of ammonia and nitric acid were quantified as ammonium and nitrate using ion chromatography.

Effective August 27, 2004, the TABLE COLUMN NAME and TABLE COLUMN CAS IDENTIFIER values in the main data table were changed from ammonium and nitrate to ammonia and nitric acid to clarify that these are gas-phase measurements. The data set name was changed from NARSTO EPA_SS_HOUSTON Ammonium and Nitrate Data to NARSTO EPA_SS_HOUSTON Ammonia and Nitric Acid Data. No data values were changed.

The Houston Supersite is one of several Supersites that was established in urban areas within the United States by the EPA to better understand the measurement, sources, and health effects of suspended particulate matter (PM). The overall goals were to characterize the composition and identify the sources of PM in Southeastern Texas, to develop and test new methods for characterizing fine PM, and to collect data on the physical and chemical characterization of fine PM that can be used to support exposure and health effects studies.

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.