PM2.5 can come from any kind of combustion engine. It also comes from rubber-road contact, among other sources. Even as the technology improves with decades of

PM2.5 can come from any kind of combustion engine. It also comes from rubber-road contact, among other sources. Even as the technology improves with decades of R&D, it’s inevitable that fine particulate matter results and potentially enters our bloodstream. https://www.epa.gov/pm-pollution/particulate-matter-pm-basics#PM https://www.epa.gov/pm-pollution/particulate-matter-pm-basic...