Particulate- and gaseous-pollutant data gathered during 1968 by the cooperating stations of the various National Air Surveillance Networks provide information about air quality in the United States. Data from independent state and local sampling networks that have contributed their results to the National Aerometric Data Bank are included. Data are presented on suspended particulate pollutants, including data on benzene-soluble organic fractions and on metallic and nonmetallic inorganic constituents; on soiling index; and on gaseous pollutants. Data are given separately for urban and nonurban sites. Annual arithmetic or geometric means of 24-hour average concentrations measured by the Hi-Vol Network and the Gas Sampling Network are presented. The minimum detectable concentrations for each of the 16 metals and 4 nonmetallic inorganic ions are listed. The distribution by population of 1968 annual averages for total particulate, nitrogen dioxide, and sulfur dioxide are presented; gaseous pollutant data for the six Continuous Air Monitoring Projects for the period 1964 through 1968 are reported. (Author)