How Covid-19 Pandemic and Vehicle Electrification Impact Global Airborne Tire Wear Particle Emissions

A reduction in global air pollution and transport activity has been evident as a result of COVID-19 lockdowns. The tire wear particle (TWP) has long been considered an important contributor to non-exhaust road traffic emissions that can adversely affect human health. The impacts of COVID-19 lockdowns and vehicle electrification on TWP emissions, however, remain uncertain. Here we linked vehicle kilometers traveled (VKT) estimates covering demography, socio-environmental, and transportation features and emission factors to predict global TWP emissions. We showed that country-specific VKT from billion to trillion vehicle-kilometer resulted in 103–105 metric tons of airborne TWP mass annually, with the highest emissions from passenger car in the period 2015–2019. On average, we found that global airborne TWP emissions had substantial decreased (up to ~33%) during COVID-19 lockdowns and pronounced increased (by a factor ~1.9) from vehicle electrification by the next three decades. We underscored the necessity of TWP emissions control among United States, China, and India. Our findings can be of great use to environmental transportation planners for devising vehicle/tire-oriented decision support tools. Our data offer information to enhance TWP-exposure estimates, to examine long-term exposure trends, and subsequently to improve health risk assessment during pandemic outbreak and future electrification.