Exposure to air-borne wood preservative chemicals was assessed at three CCA-and three creosote-impregnation installations. Concentration of aerial CCA were low and did not exceed threshold limits. Exposure to highest concentration occurred during opening of the treating cylinder. It is recommended that changes in this routine should be made. Concentration of creosote caried considerably depending on the working moment. Highest concentration was during opening of the treating cylinder, when concentration of benzopyrene was 20% of the threshold limit. Further epidemiological studies on creosote workers are recommended. -- AATA