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Abstract

Transportation is a convenient way to incorporate an active lifestyle, in addition to reducing environmental pollution. This study estimates the changes in carbon dioxide (CO2) emissions and the health co-benefits from two new mass rapid transit (MRT) lines in Greater Kuala Lumpur, Malaysia.Changes in CO2 and air pollutant emissions were estimated from motor vehicle activity based on the travel information collected from a survey. Health effects were estimated using a comparative health risk assessment method. Exposure to air pollution was modelled based on the reduction in ambient PM2.5 concentration. Traffic injury was estimated using a constant risk per distance for each transport mode. Physical activity was modelled based on the amount of walking to or from the stations. Health outcomes were calculated as changes in premature deaths and disability adjusted life years (DALYs).The two MRT lines would reduce 337,800 t of CO2 equivalent per year from private transportation. However, the use of motor vehicle in the station access-egress would offset 28% of the total carbon savings. The ambient PM2.5 concentration would be reduced by 0.12 µg/m3, preventing 5 deaths and 104 DALYs per year. Reduced traffic injuries would prevent 88 deaths and 6300 DALYs per year, while increased walking would prevent 90 deaths and 3200 DALYs per year. Sensitivity analysis revealed that travel distance, modal shift and station access-egress distance could considerably change CO2 emission reduction, while relative risks of physical activity could significantly affect attributable burden of diseases.The two MRT lines would reduce 6% of CO2 equivalent emission from private motor vehicles in Greater Kuala Lumpur and bring important health co-benefits to the population. However, strategic planning around the MRT stations for access and egress is necessary to achieve maximal benefits.