Maximilian - Well, if we're sticking with the smoking example, how about this as far as determining your risk.

The smog you are exposed to just from living in a moderately populated city is WAY more likely to give you lung cancer than second hand smoke.

And given the average person's risk of getting lung cancer from living in a moderately populated city is so low it's almost funny, I would say you're fine.

The second hand smoke thing always cracked me up, long before I ever smoked. It's a social campaign, not a health one. And a very damaging and divisive social campaign at that which has in fact served to make smoking more appealing.



Sorry. As you were saying, though. I reckon there's a period of time it takes for a given particle to no longer be airborne. What that time is though probably depends on the substance.

At that point I would think it would be reasonably safe. After all, we're breathing in particles of whatever all the time. It's the dose that matters.