摘要：Objectives. We quantified health benefits of transportation strategies to reduce greenhouse gas emissions (GHGE). Methods. Statistics on travel patterns and injuries, physical activity, fine particulate matter, and GHGE in the San Francisco Bay Area, California, were input to a model that calculated the health impacts of walking and bicycling short distances usually traveled by car or driving low-emission automobiles. We measured the change in disease burden in disability-adjusted life years (DALYs) based on dose–response relationships and the distributions of physical activity, particulate matter, and traffic injuries. Results: Increasing median daily walking and bicycling from 4 to 22 minutes reduced the burden of cardiovascular disease and diabetes by 14% (32 466 DALYs), increased the traffic injury burden by 39% (5907 DALYS), and decreased GHGE by 14%. Low-carbon driving reduced GHGE by 33.5% and cardiorespiratory disease burden by less than 1%. Conclusions: Increased physical activity associated with active transport could generate a large net improvement in population health. Measures would be needed to minimize pedestrian and bicyclist injuries. Together, active transport and low-carbon driving could achieve GHGE reductions sufficient for California to meet legislative mandates. Greenhouse gas emissions (GHGE) linked to global warming and climate change are the most significant threat confronting public health in the 21st century. 1 Approximately 7% of US GHGE are generated in California, which is the 12th largest emitter worldwide. 2,3 California’s transportation sector is the single largest source (38%), 2 and personal passenger vehicles account for 79% of that sector’s GHGE. The State of California has enacted legislation to achieve a 2050 goal of reducing GHGE to 80% below its 1990 level. Strategies to reduce GHGE include reducing carbon dioxide (CO2) emitted per mile and reducing total car miles traveled. 2 Emerging technologies for lower carbon fuels and alternative-fuel vehicles (electric, fuel cell, or gas–electric hybrids) typify the former approach. The latter approach recognizes that a large proportion of urban automobile trips could be walked or bicycled, which affords opportunities for physical activity and reducing air pollution. Because physical inactivity is linked to obesity and chronic diseases, active transport could play an immensely important role in promoting public health while decreasing air pollution and transportation-related GHGE. Several researchers have recently attempted to quantify the health benefits of reduced car travel and increased active transport, 4–8 focusing on physical activity and air pollution. However, none have simultaneously addressed a US population and its road traffic injuries, 7 which accounted for 3.1% of the overall US burden of disease and injury 9 in 2004 and had a disproportionate impact on pedestrians and bicyclists per mile traveled. 10 We quantified potential health cobenefits and harms of different strategies to reduce transport-related GHGE in the San Francisco Bay Area, California.
