This testimony before the Subcommittee on Environmental Pollution concerned several topics relating to air quality standards including new information, safety margins, scientific defensibility, needed additional air quality standards, need for more restrictive secondary standards, and the emphasis of current research in this field. The testimony began with a general overview, continued with a discussion of regulated and unregulated pollutants, and closed with observations on needed research. Specific air pollution problems noted include a nitrogen-dioxide (10102440) standard, a short term (1 to 3 hour) air quality standard, photochemical oxidants, carbon-monoxide (630080), sulfur oxides, total suspended particulates, particulate aerosols, toxic trace elements, organic chemicals, sulfuric-acid (7664939), sulfate salts, complex sulfur (7704349) compounds, water soluble sulfates, arsenic (7440382) compounds, vinyl-chloride (75014) monomers, polyvinyl-chlorides, solvents, and chlorinated compounds. Indoor air pollution was an additional topic which had received little attention. Five major difficulties were listed which must be addressed if an understanding is to be gained of the dose response relationships linking environmental agents to adverse effects on human health. These included the usually insufficient information regarding the magnitude and frequency of exposure to these agents, the complexity of the links between exposure and disease, the shortcomings of vital records and morbidity assessment, the lack of a biologically coherent research data base with clearly interlocking clinical, occupational, epidemiological, and toxicological studies, and the interactive effects of exposures to multiple pollutants.