The NARSTO_EPA_SS_HOUSTON_NO3_SO4_C_DATA files contain continuous measurements of PM2.5 nitrate, PM2.5 sulfate, and PM2.5 carbon collected during August 12, 2000 through November 5, 2001 at the Aldine, Deer Park, and LaPorte Houston Supersite monitoring locations. Nitrate measurements were collected using the R&P 8400N Method. Sulfate and carbon measurements were collected using the Prototype ADI Particulate Sulfate and Carbon Monitor Method.The Houston Supersite is one of several Supersites that was established in urban areas within the United States by the U.S. Environmental Protection Agency (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 particulate matter in Southeastern Texas, to develop and test new methods for characterizing fine particulate matter, and to collect data on the physical and chemical characterization of fine particulate matter that can be used to support exposure and health effects studies.NARSTO (formerly North American Research Strategy for Tropospheric Ozone) is a public/private partnership, whose membership spans government, the utilities, industry, and academe throughout Mexico, the United States, and Canada. The primary mission is 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 available.