Health Benefits of Traffic-related Particulate Matter Control Policies: The Case of Bangkok, Thailand

Urban air pollution is a major public health concern in some large developing metropolitan areas in Asia such as the capital city of Thailand, Bangkok. Since the 1990s, this area has been suffering from severe ambient particulate matter (PM) pollution mainly attributable to its wide use of diesel-fueled vehicles and motorcycles with poor emission performance.While the Thai government strives to reduce emissions from transportation through enforcing policy measures, the link between specific control policies and associated health impacts is inadequately studied. Furthermore, despite the fact that the actual effects of some mitigating policies, such as the in-use vehicle inspection and maintenance (I/M) programs, may be greatly uncertain, this uncertainty issue has traditionally been ignored in evaluating the impacts of a policy on public health. This dissertation estimated the health benefits potentially achieved by the new PM-related I/M programs targeting all diesel vehicles and motorcycles, as well as several vehicle retrofitting or repowering programs in the Bangkok Metropolitan Region, linked the levels of PMemission reductions available from the I/M programs with the health benefits and costs of the programs, and quantified the impacts of key I/M design elements on emission reductions. The benefits were estimated by using the health benefit analysis framework that integrates air quality modeling, exposure assessment, exposure-response assessment and economic valuation, and the effectiveness of an I/M program was iv evaluated by utilizing a new analysis approach called I/M Design. In addition, a stratified meta-analysis was conducted to develop a mobile source specific PM concentration-response coefficient appropriate for this study. The results indicated that traffic-related PM control policies potentially yield substantial health benefits relative to the business-as-usual scenario. Particularly, it was found that with a high level confidence, the I/M programs will produce total health benefits that outweigh the large expenditures on policy implementation. Nevertheless, the uncertainty in the effectiveness of such programs needs to be taken into account so that the associated health improvement is appropriately evaluated. Finally, I/M design considerations should address some key design elements such as the problem vehicle identification rate in order to improve the effectiveness of the programs.