Exposure to third-hand cigarette smoke – the nasty residue that clings to clothing, carpets, and furniture – is just as deadly as sucking down a cigarette. A new study found that third-hand smoke gets progressively more toxic the longer it lingers, posing a serious health hazard long after a butt has been put out.

Researchers subjected lab mice to levels of third-hand smoke that mimicked what humans encounter in smoking environments. Following exposure, the mice had significant lung and liver damage, became hyperactive, and had a harder time healing wounds. According to the researchers, the same effects are often seen in smokers and in people exposed to second-hand smoke, proving that third-hand smoke is equally dangerous.