Smoking, as we all know, is bad for you. We also know that inhaling other people's smoke is nearly as unhealthy as lighting up on your own.

It Doesn't Disappear

Scientists are finding that just being in a car or building where people have been smoking is potentially bad news.

When smoke curls off the lit end of a cigar or cigarette, it may seem to vanish. But the nicotine particles and many other chemicals in cigarette smoke don't literally disappear. They soak into walls, floors, furniture, and even clothing.

Beyond smelling bad, this so called third-hand smoke can react with common household chemicals to form toxic compounds.

Third-Hand Smoke

So if you're in a house or car where people smoke and you brush up against a wall, rug, or furniture, your skin could come into contact with dangerous chemicals.

Third-hand smoke is especially risky for infants and toddlers, who are most likely to roll around on smoke soaked carpets.

A Real Threat

It's not yet clear how potent smoke residue is, or how likely it is to cause diseases like cancer. But the study suggests that third-hand smoke may indeed pose a threat.

And once smoke soaks into a surface, it's usually there to stay. So unless you want smokey residue on your skin, it's best to avoid places where people light up.