I didn't know this, guess I'd never thought to look it up.
If 16% of deaths can be attributed to pollution, and some percentage are vehicle related, accidents in general, preventable disease / infections, etc etc...
How many deaths per year should we expect if all of those things could be reduced / minimised / eliminated?
We surely would. But the gains may be more (or less) than you think.
I remember a gerontologist showing some math where if you prevented all heart disease you'd only gain about 4 years of human lifespan (since most of those people would soon get cancer); similarly if you prevented all cancer you'd only get about 4 years as well (since most of those people would get heart disease).
But if you prevented both, you'd get something north of 10 years of average lifespan.