In-vehicle exposure to carbon monoxide emissions from vehicular exhaust: A critical review

Vehicle-induced emissions constitute a major source of air pollutants, particularly in urban areas, where heavy traffic is common occurrence. Contaminated air can flow into enclosed micro-environments, including vehicle compartments. Among various exhaust emissions, carbon monoxide (CO) was the first indicator examined in passenger compartments. This paper presents a critical review of worldwide research work conducted to characterize CO exposure inside vehicles. Measurement methodologies for field testing are presented alongside impacts of various factors on in-vehicle CO exposure, including outdoor CO levels, roadway type, ventilation mode, weather conditions, and vehicle characteristics. Results of in-vehicle CO exposure measurements in various cities are compared. Modeling efforts to characterize in-vehicle CO exposure and relate it to potential explanatory factors are also discussed. Based on the review findings, limitations and future needs are defined.