Carbon monoxide is a major dr pollutant, its main source being vehicular exhaust. Peshawar, like other major cities is facing a serious problem of dr pollution due to rapidly increasing traffic. Carbon monoxide level during 600 hn to 1800 hrs was studied at sixteen different locations with maximum traffic density. Twelve cart of the sixteen locations were found to have an average carbon monoxide concentration above the threshold limits of 9 ppm for 8 hours exposure whereas, at one location average carbon monoxide concentration reached the limit of 35 ppm for one hour average exposure. Results suggest that at these twelve locations, the calculated carboxyhaemoglobin level that could be present in the blood of people exposed for 8 hours are in the range 204-4.85% which can adversely affect the central nervous system and can bring changes in psychomotor functions.