Health benefits from cleaner vehicles and increased active transportation in Seattle, Washington

Climate mitigation policies that focus on the transportation sector yield near-term health co-benefits that could motivate policy action.

We quantified CO₂ emission reductions as well as the air pollution and health benefits of urban transportation policies promoting electric vehicles (EV) and walking and bicycling in Seattle, Washington.

We compared a business-as-usual scenario projected to 2035 with intervention scenarios in which 35% of gasoline vehicles were switched to EV, and 50% of car trips less than 8 kilometers were replaced by walking or bicycling. We modeled changes in primary traffic-generated oxides of nitrogen (NO_x) and fine particulate matter (PM_2.5) as well as walking and bicycling activity, CO₂ emissions from traffic, and fatal traffic injuries due to the transportation policy scenarios. We estimated the impacts of these changes on annual cases of asthma and premature mortality in the Seattle population.

Increasing the use of EV, walking, and bicycling is estimated to reduce CO₂ emissions by 744 tons/year (30%) and lower annual average concentrations of primary traffic-generated NO_x and PM_2.5 by 0.32 ppb (13%) and 0.08 μg/m³ (19%), respectively. In Seattle, the lower air pollutant concentrations, greater active transportation, and lower fatal traffic injuries would prevent 13 (95% CI: -1, 28), 49 (95% CI: 19, 71), and 5 (95% CI: 0, 14) premature deaths per year, respectively and 20 (95% CI: 8, 27) cases of asthma per year.

Moving towards cleaner vehicles and active transportation can reduce CO₂ emissions, improve air quality, and population health. The resulting public health benefits provide important motivation for urban climate action plans.

Using key components of the health impact assessment framework, we quantify the environmental and health benefits of urban transportation policy scenarios that promote electric vehicle use and replace short car trips with walking and bicycling as compared with a business as usual scenario in 2035. Our findings demonstrate that transportation scenarios promoting cleaner vehicles and active transportation can reduce CO₂ emissions, improve air quality, and increase physical activity levels, resulting in significant public health benefits.