Predicting personal exposure levels to carbon monoxide (CO) in Taipei, based on actual CO measurements in microenvironments and a Monte Carlo simulation method

Abstract In order to evaluate the severity of carbon monoxide (CO) pollution in Taipei, this study conducted a survey of commuting patterns (in a district) for random samples of primary school students and adult workers, and carried out CO measurements in vehicles and near roadsides. A Monte Carlo simulation was then implemented to estimate 1- and 8-h CO exposure levels for the population. The microenvironment of the roadside included both the sidewalk and the corridor (a sheltered walkaway further removed from the road than the sidewalk). By computer simulations, this study showed that commuters on motorcycles and public buses were exposed to the highest CO exposure levels among all commuters on the roads in Taipei. This study also demonstrated that the Monte Carlo simulation method could better estimate CO exposure levels for the general public. It was found that roadside-fixed monitoring stations operated by the Taipei BEP (Bureau of Environmental Protection) underestimated the general population's 1-h CO exposure levels. For adult workers, the roadside-fixed monitoring stations reasonably estimated the roadside business workers' 8-h CO exposure levels, but overestimated the exposure levels of general adult workers commuting by public bus, except for bus drivers whose CO exposure levels were underestimated. It is suggested that the computer simulation method can be used to better guide air quality management plans instead of only using the fixed-site monitoring data. The simulated results indicate that the CO exposure levels of commuters on motorcycles and public buses are high enough that prompt control measures are warranted in Taipei.