The overall objective of this Research Triangle Institute pilot study was to develop and evaluate a minimal testing protocol which could detect and quantify the mutagenic potential of ambient air. The cost-effective biological and chemical testing protocol developed under this program outlines sampling, chemical fractionation/identification, and bioassay techniques which are applicable to air pollution testing of both ambient air particles and vapors. More specifically, this study: (1) evaluated the three stage Massive Air Volume Sampler (MAVS), developed by Battelle for collection of air particle samples; (2) developed and utilized a chemical fractionation scheme for solvent extraction of organic compounds from ambient air particles; (3) evaluated a GC/MS/Computer analysis system designed to chemically identify signature mutagens/carcinogens; and (4) utilized and evaluated modifications of the Ames/Salmonella typhimurium mutagenicity assay for ambient air particles and vapors.