An assessment of the occupational exposure to styrene and associated chemicals in Denmark was carried out by retrieving all measurements from the archives of the Danish National Institute of Occupational Health. A total of 2,528 air samples containing styrene had been collected from 256 workplaces during the years 1955‐88 and analyzed by the chemical laboratory at the Institute. The mean for all samples was 265 mg/m3. The concentration decreased from 714 mg/m3 in the early period (1955‐70) to 172 mg/m3 in the late period (1981‐88). Spraying and unspecified lay‐up and production of boats, carriages, and stationary containers were associated with the highest concentration. A total of 34 chemicals were measured. The most frequent co‐contaminant to styrene was acetone, which was measured in 2,263 samples with a mean concentration of 131 mg/m3. Dichloromethane was measured in 208 samples with a mean concentration of 51 mg/m3, xylene in 148 samples with a mean concentration of 49 mg/m3, and toluene in 116 samples with a mean concentration of 113 mg/m3. The study was undertaken to analyze historical styrene concentrations in air to aid in the selection of industrial cohorts to be included in epidemiologic studies.