Lead rains down on us daily from airplanes (as their fuel is still lead based.)Have worked outside for around 50 years or so. Now and then feel a little burning sensation and pass it off. Then again around 50 tonnes of meteoric space debris falls to Earth every day.
You never know, at some point in your life, and chances are pretty good, you could be hit by Star Dust and not even know it
There's exhaust from vehicles and factories.
Other burnings, like forest fires, are more common.
Heavy metals, volatile organic chemicals, Phthalates.... and a weakening ozone layer.