Abstract
Background: Air pollution caused by automobiles can pose serious health hazard due to urbanization. Carbon monoxide (CO) is one of the six criteria for air pollution related to urbanization. Urban drivers are occupationally at risk of exposure to CO.

Aims and Objectives: This study was undertaken to assess the levels of CO in breath among the exposed group of urban automobile drivers and to compare breath CO levels among various group of drivers based on their years of experience or duration of exposure.

Materials and Methods: A cross-sectional analysis of breath sample for the presence of CO was conducted on automobile drivers (n = 101) using different type of motor vehicles in urban Chennai using breath CO analyzer (Vitalograph 29700). Mean CO levels were compared among groups using ANOVA. Proportion in groups was assessed by χ2/Fisher’s exact test.

Results: The mean CO of the breath analysis was 2.45 parts per million (ppm) which corresponds to the mean carboxyhemoglobin of 0.68%. Exhaled breath CO was 3–4 ppm in 22.8% of the drivers. 8.9% of the drivers had exhaled breath CO above 9 ppm. Statistically significant difference was observed between duty hours and exhaled breath CO (P < 0.01). Drivers who were smokers had a significantly higher breath CO (P < 0.00). Drivers who used gas as fuel were having statistically significant higher breath CO (P < 0.05).

Conclusions: CO is potential environmental toxin of air due to vehicle exhaust. Drivers are constantly exposed, which is evident by our report of having higher breath CO with long duty hours. Smoking adds to environmental exposure of CO to automobile drivers.

Key words: Air Pollution; Breath Analysis; Carbon Monoxide; Drivers; Occupation