Exposure level of carbon monoxide and respirable suspended particulate in public transportation modes while commuting in urban area of Guangzhou, China

This study examined commuter exposure to respirable suspended particulate (PM 10 and PM 2.5) and carbon monoxide (CO) in public transportation modes in Guangzhou, China. During the sampling period, a total of 80 CO, 80 PM 10 and 56 PM 2.5 samples were conducted in four popular commuting modes (subway, air-conditioned bus, non-air-conditioned bus and taxi) while running in typical urban routes. The results show that the PM 10 as well as CO level is greatly influenced by the mode of transport. The highest mean PM 10 and CO level was obtained in a non-air-conditioned bus (203 μg m −3) and in an air-conditioned taxi (28.7 ppm) , respectively. Noticeably, the exposure levels in subway are lower than those in the roadway transports. The ventilation condition of the transport is also a crucial factor affecting the in-vehicle level. There was statistically significant difference of PM 10 (p