Simply sitting in a cinema to watch a movie can expose people to the equivalent of one to 10 cigarettes’ worth of secondhand smoke, according to a new chemical analysis.
Research has already shown that cigarette smoke releases a host of chemicals that are harmful to humans. Both the smoker and people exposed to the secondhand smoke can suffer negative health effects from these substances, which include benzene, formaldehyde, and toulene. While legislation has cut down on where people can smoke in public, smokers still bring these chemicals with them via their clothing and belongings and release them into the environment, a phenomenon scientists call thirdhand smoke. This new study quantifies the impact that thirdhand smoke can have.
“This represents significant but poorly understood health risks to nonsmokers and a source of reactive chemicals indoors,” Drew Gentner, one of the study’s authors from Yale University, said in a press conference. “So, while questions for scientists and policymakers remain, it is clear that the myriad of chemicals from cigarette smoke do not remain isolated to where they’re smoked.”
The researchers collected measurements at a cinema complex in Mainz, Germany in January and February 2017 in a well-ventilated theatre. They used a portable version of a machine called a proton transfer mass spectrometer, along with further lab techniques, to determine the concentrations and identities of the chemicals in the air. The theatre showed four or five movies per day during the sampling time, and the researchers specifically monitored the air during the G-rated movie Wendy and the MA-15+ rated movies Resident Evil and Irre Helden. The average audience size was approximately the same for each film.
Despite laws that have banned indoor smoking in Germany for 15 years and the well-ventilated room, the researchers still found 35 different volatile organic compounds associated with tobacco smoke, including well-known carcinogenic compounds like benzene. The chemical levels jumped up at the start of screenings, then slowly decreased throughout the films. When smokers arrived late, they appeared on the data as another increase in the concentration. The spikes were generally higher during the MA-15+ rated movies.
Overall, the researchers reported that the level of exposure was as if one to 10 cigarettes had been smoked in the room, according to the paper published in Science Advances.
The scientists wouldn’t speak to the overall harm, since the purpose of the study was to quantify the exposure, and the health effects of thirdhand smoke aren’t fully understood, Gentner said. They hope others researchers will dig into the effects and prevalence of thirdhand smoke. They also want smokers to be more aware of what they’re bringing into public spaces when they smoke.
“They themselves remain a source of those chemicals when they go back inside, which may be particularly important in the presence of small children or sensitive populations,” Gentner said.
Suzaynn Schick, associate professor at the University of California Centre for Tobacco Control Research and Education who was not involved in the study, told Gizmodo that she was glad someone conducted this research. She agreed that these findings are especially important to parents of young children, for whom early exposure to high levels of these chemicals could cause developmental issues. She said she’d like to see further number-crunching to discuss how the levels and overall exposure compared to the number of people present in the theatres.
“The simplest bottom line is that thirdhand smoke is real,” Schick said. “This isn’t some crazy imagining. You can smell it and you can measure it, and when you smell cigarette smoke on someone, you are being exposed to the chemicals from the smoke.”