Exposure to Carbon Monoxide while Commuting in Popular Modes of Transport in Karachi, Pakistan

Motor vehicles are the single largest source of toxic carbon monoxide in Karachi because advance emission control devices are not fitted in them mainly due to non-availability of low sulfur or sulfur-free fuel. On the contrary, commuters' exposure to carbon monoxide has not yet been investigated, while commuting in any motor vehicle of the city. Therefore, the present study investigated commuter's exposure to carbon monoxide, while travelling in nine different popular modes of transport. The exposure to CO concentrations was recorded inside the buses of seven standard routes of the city. Similarly, exposure to ambient carbon monoxide was also explored, while riding a motorbike on two different routes of the city. On an average, he came in contact with 6.82 ± 2.66 ppm CO during 7576 minutes travelling on nine routes of the metropolis. He was exposed to the highest CO concentration (15.20 ± 9.59 ppm), while riding a motorbike through Route 1 that passed through heavily populated neighborhood. Rider's exposure to carbon monoxide was found significantly (p < 0.05) correlated with wind velocity. As a whole, commuter's exposures to carbon monoxide during evening was significantly (p < 0.01) higher than those of the morning sessions. The present study will provide baseline information for reducing human exposure to the deadly carbon monoxide.