Carbon monoxide exposure inside UK road vehicles: a pilot study

Environmental CO presents a risk to public health. The effects of chronic low-level CO exposure are well-documented, with pregnant women, the unborn and children being particularly vulnerable. Although a number of studies have investigated the phenomenon, its current prevalence in the UK has not been examined. To address this, this study sampled CO levels from 33 vehicles driven by 28 participants. Drivers were members of the public using their cars for purposes including commutes and personal use. The study excluded vehicles carrying smokers. In all, 20 vehicles logged (60.6 per cent) logged non-zero CO at least once. Mean average ppm CO exceeded the WHO target limit of 4mg/m3 (3.49 ppm) in 4 vehicles; peak ppm CO exceeded this limit in 13 vehicles. Peak single-journey mean CO was 192.17 ppm and overall mean all-journey CO was 6.63 ppm, median 0.02 ppm. Patterns of detected CO, in some cars, were suggestive of internal fume leakage. There was a significant positive correlation between vehicle age and in-cabin CO levels. While the sample size was small, these results give grounds to consider that vehicle drivers and passengers in the UK may be exposed to CO within the passenger cabin due to leakage from the exhaust system. Wider investigation of the issue, in order to determine an appropriate public health policy response, is warranted.