Estimating Reductions in Premature Mortality Attributable to Outdoor Ultrafine Particles with Increasing Prevalence of Electric Vehicles and Other Tailpipe-Related Emission Reduction Scenarios

Emissions from combustion engine vehicles result in elevated concentrations of ambient ultrafine particles (UFPs; particulate matter < 100 nm) in urban environments. Long-term exposure to ambient UFPs has been associated with increased risk of mortality. We modeled the relationship between UFP emissions from combustion engine vehicles and outdoor UFP concentrations in Toronto and Montreal, Canada. Using these models, we predicted the health benefits of introducing electric vehicles (EV) and reducing tailpipe-related emissions under various scenarios from 2021-2040. The scenario with the greatest total number of premature deaths avoided included accelerated EV adoption, accelerated retirement of pre-2007 heavy-duty combustion engine vehicles, and decreased traffic volumes resulting in 2538 (95% CI: 2128, 2946) nonaccidental deaths avoided in Toronto and 1116 (95% CI: 927, 1285) nonaccidental deaths avoided in Montreal during the study period (2021-2040). Scenarios accelerating the retirement of pre-2007 heavy-duty combustion engine vehicles (without introducing new EVs) also resulted in large reductions in nonaccidental deaths in both cities as long as combustion engine vehicle emission factors were reduced annually. Policies that reduce UFP emissions in urban areas including the transition from combustion engine vehicles to EV will likely have meaningful health benefits in terms of reductions in premature mortality.