We all know smoking kills and secondhand smoke can harm friends and relatives. But now mounting research shows that thirdhand smoke — the chemical residue left behind by cigarettes — can stick around for years, negatively impacting health by being absorbed into the body.
A study published earlier this month showed that outdoor tobacco smoke can seep into non-smoking buildings and coat surfaces with its chemical residue. Furthermore, ventilation systems can make those chemicals airborne and carry them throughout the building where they settle onto people’s desks, chairs, clothes, skin and food.
The chemicals can then get ingested through the skin or through food or drink. A separate study of a casino that banned smoking six months prior showed heavy thirdhand smoke remaining on the carpets and walls.
“It shows that just because you’re in a nonsmoking environment, it doesn’t mean you aren’t exposed to tobacco,” says atmospheric chemist Peter DeCarlo, lead author of the ventilation study. “That Uber car you jump into, the hotel room you stay in, even a classroom where smoking hasn’t been allowed for decades: These are places where you are often exposed to a lot more than you expect.”
Thirdhand smoke contains more than 250 chemicals including carcinogens, cyanide, lead, arsenic and butane. Several experiments with mice have shown that thirdhand smoke makes mice more susceptible to lung cancer, liver damage and diabetes. Mice have a genetic code very similar to humans’ and are susceptible to many of these same diseases from many of the same causes as we are.
The American Academy of Pediatrics says that thirdhand smoke is most likely to harm “children, people with breathing problems, pregnant women, the elderly, and animals.” They also say that e-cigarettes and vaping can leave behind hazardous thirdhand smoke as well.
And, as The Washington Post points out, “because of increasing socioeconomic disparities in smoking, low-income families are more likely to live in homes and neighborhoods where decades of smoking have led to thirdhand smoke accumulation.”
The best way to avoid thirdhand smoke is to avoid any place that allows smoking. There’s no way to completely remove it from a building, but cleaning all surfaces, cleansing the ventilation system, replacing all air filters and vacuuming or replacing all fabrics can help.