Even if you don’t smoke, and you’re inside a nonsmoking building, you could still be exposed to some of the health effects of cigarette smoke—just from someone who smokes walking inside.
A new study looked at the levels of thirdhand smoke in a nonsmoking movie theater, using mass spectrometers to measure how compounds such as dimethylfuran, benzene, and formaldehyde wafted off the clothing and skin of smokers as they entered the theater. The room was large and continuously ventilated with fresh air, but having smokers in the room meant that other moviegoers were breathing in the equivalent of the secondhand smoke from as many as 10 cigarettes.
In some cases, there was still measurable contamination even a day or two later.
“The general implication is that even in nonsmoking environments, chemicals from smoke can still make their way indoors transported by those who smoke or were exposed to smoke,” says Drew Gentner, associate professor of chemical and environmental engineering at Yale University and one of the authors of the study. While some previous studies looking at thirdhand smoke focused on smoke left behind in areas where smoking was allowed, the new study took a different approach.
The researchers studied the air coming from a vent in the room and didn’t track the smokers themselves, though it’s likely that the biggest impacts came from those who had smoked immediately before buying a ticket and walking inside the theater. “‘Fresher’ smoke on clothes and other surfaces will likely release higher amounts of smaller, more volatile compounds and at higher rates,” Gentner says. Emissions peaked as people walked inside the theater and then decreased, but they didn’t completely disappear even when the movie ended and the audience left. In some cases, there was still measurable contamination even a day or two later, as chemicals that were absorbed into theater seats and other surfaces reentered the air.
For someone concerned about the health effects of cigarette smoke—since no amount of smoke is considered safe to breathe—it might make sense to choose a different seat if you’re sitting next to someone who smells particularly like smoke (though when assessing your risk you should also consider that simply breathing the air outside is often very bad for your health). Some buildings might try to improve ventilation or air filtration, thought that can’t completely eliminate the problem. It raises other questions: At a hospital, for example, is it enough to require staff to smoke outside? As more research happens in the field, Gentner says, policymakers may begin to consider new types of nonsmoking policies. “Our work seeks to advance our understanding of the fate of chemicals from cigarette smoke and catalyzes an important discussion about human exposure to thirdhand smoke off-gassing from people,” he says.