Researchers found those chemicals could be detected in the air flowing out of a non-smoking movie theater through exhaust ducts, according to the report in Science Advances.
“Our results show that people are substantial carriers of third-hand smoke contaminants,” said Drew Gentner, an associate professor of chemical and environmental engineering at Yale University in New Haven, Connecticut.
“So, the idea that someone is completely protected from the potential health effects of cigarette smoke because they’re not directly exposed to second-hand smoke is not the case,” Gentner said. “Smokers or those exposed to cigarette smoke can remain a source of these chemicals when they enter non-smoking environments, which may be especially important in the presence of small children or sensitive populations.”
Other studies have described third-hand smoke as a contaminant that adheres to walls and other surfaces in homes and sticks around long after the smoker has left.
Gentner and his colleagues put highly sensitive sensors in the air exhaust duct of a non-smoking movie theater to see if they could detect third-hand smoke chemicals emitted into the air from the clothing and bodies of smokers. The sensors sent data to mass spectrographs where the chemical content of the outgoing air was analyzed.
The researchers chose to focus on the outflowing air during R-rated movies, under the assumption that only adults would be in the audience and a greater number of them might be smokers or people who had been in the vicinity of a smoker.
“Even though the audience for R-rated movies was relatively small compared to the G-rated movies, we saw a lot of clear markers of tobacco smoke off-gassing,” Gentner said. “They all spiked upon the arrival of the moviegoers and decreased over time in many cases, but there was lingering contamination left behind.”
During G-rated movies the amount of contamination was minor, Gentner said.
The researchers found a diverse range of tobacco-related volatile compounds in the air flowing through the exhaust ducts during the R-rated movies. Depending on which compound was being measured, the amounts exuded during a given movie showing were equivalent to roughly one hour of exposure to 1 to 10 cigarettes’ worth of secondhand smoke. They included multiple hazardous air pollutants, such as benzene and formaldehyde, along with nicotine.
“These results, along with past surface measurements of nicotine in non-smoking environments, indicate that this is occurring frequently around us,” Gentner said.
What the researchers don’t know is how much of the third-hand smoke chemicals end up inside the moviegoers. That’s something for a future study, Gentner added.
The study team also acknowledges that they lacked data to account for certain chemicals that might have other sources, and couldn’t distinguish whether some substances like nicotine might have also come from e-cigarette residues.
“This is a superb paper,” said Steven Stellman, a professor of clinical epidemiology at Columbia University’s Mailman School of Public Health in New York City. “The level of science is first rate.”
The study opens the door to more research into the effects of the third-hand smoke that clings to smokers, Stellman said. Those studies could investigate health risks associated with this kind of exposure, he added.
“What’s missing from this study, from a public health point of view, is the actual potential toxicological exposure of individuals,” Stellman said. “How much of this can you measure in the body?”