Carbon monoxide levels measured in major commuting corridors covering different landuse and roadway microenvironments in Hong Kong

Vehicle exhaust is the major source of pollutant in modern cities. About half of Hong Kong residents are living in suburban or rural areas. They need to traverse through tunnels, highways, urban street canyons and other road conditions in different landuse areas when they traverse to work in urban centres or new towns. Also, there is increasing traffic, especially trucks across the border between Hong Kong and mainland China via several border highways. This study helps us in assessing the exposure level of suburban and cross border commuters. Carbon monoxide (CO) is used as a tracer for traffic emission. An experimental vehicle traversing major commuting corridors were used to measure CO levels in different landuse and roadway microenvironments including tunnels and highways. The air samples were taken simultaneously at the outside and inside of a travelling vehicle. Result indicates that the pattern of fluctuation of the out-vehicle and in-vehicle CO level vary with different landuse areas. The variation pattern of in-vehicle CO level is closely related to that of out-vehicle level. The effects of the out-vehicle CO concentration on the in-vehicle CO concentration under different roadway conditions in various landuse categories are examined. There is an indication that external air pollutants penetrated into the in-vehicle compartment through car body cracks, ventilation system. From our observation, the exhaust of a nearby petrol vehicle contributed significantly to the in-vehicle CO level. The use of low standard of diesel fuel from Shenzhen in mainland China leads to higher CO level near border area.