Graphical summaries of the concentrations of atmospheric contaminants are presented for over 3700 sites at which one or more of the contaminants are monitored. Also included are data on ambient humidities and temperatures. The data provide a comparison base for design and test results calibration. Atmospheric upper limit values (the maximum average values sustained over field exposures of 10 to 30 years) are defined for the following: temperature, humidity, aldehydes, ammonia, ammonium ion, benzene-soluble organics, chloride ion, gaseous chlorine, fluoride ion, hydrogen sulfide, nitrate ion, nitric oxide, nitrogen dioxide, and total particulate matter. Indoor and outdoor concentrations as a function of time and site are also discussed.