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 χ