NARSTO_EPA_SS_HOUSTON_RAPID_SPMS_DATA is the North American Research Strategy for Tropospheric Ozone (NARSTO) Environmental Protection Agency (EPA) Supersite (SS) Houston, Rapid Single-Particle Mass Spectrometer Data. This product contains individual aerosol particles which were sized and analyzed using a Rapid Single-particle Mass Spectrometer (RSMS) in Houston during the summer of 2000. RSMS aerodynamically focuses one particle size at a time to the source region of a mass spectrometer and employs a 193 nm excimer laser to desorb and ionize the particle components. The ions are analyzed in a single time-of-flight mass spectrometer and the spectrum is digitally recorded. Spectra are only saved if the ion peak in the spectrum is above a threshold level. Background spectra were determined and flagged. Particle size scans were initiated periodically, and each size was sampled until 30 particle hits were obtained, unless the sampling time became excessive. Aerodynamic particle sizes ranged from about 40 to 1300 nm and were partitioned into nine discrete size classes logarithmically spaced, roughly, over the range. Single particle data are valuable because they:- are collected and analyzed real time so have excellent temporal resolution,- enable assessment of particle-to-particle composition variations (external mixing properties), - allow for easy identification of key particle sources since the particles retain source characteristics. The data resulting from these measurements consisted of an aerodynamic particle size and a positive mass spectrum of the components for each particle, along with the date and time of measurement and other incidental measurement parameters such as the laser pulse energy. Support for RSMS measurements was provided by the EPA Supersite program and additional funding from the EPA. 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.