> tires produce about 2,000 times more particle pollution by mass than tailpipes. (emphasis mine) The fact that the majority of tailpipe pollution is not part

> tires produce about 2,000 times more particle pollution by mass than tailpipes. (emphasis mine) The fact that the majority of tailpipe pollution is not particulate means that tailpipe pollution can be the biggest problem we need to fix, even if it isn't the biggest particle pollution problem.