Study: Third-hand smoke is just as dangerous as second-hand smoke

Car exhaust, pollution from power plants and factories, and second-hand smoke all pose serious public health risks, which is why there are so many stringent smoking bans and restrictions.

Designated smoking areas are far removed from entrances, and indoor smoking, particularly in public buildings, is a thing of the past.

However, second-hand smoke is not the only kind of exposure we should be worried about, according to a new study.

Researchers from Drexel University discovered that chemical residue from cigarette smoke, also known as third-hand smoke, can attach to clothes, hair, and surfaces, and these pollutants make their way indoors, even in non-smoking buildings.

The results, published in the journal Science Advances, show that third-hand smoke chemicals attach themselves to aerosol particles and are just a dangerous as second-hand smoke.

“While many public areas have restrictions on smoking, including distance from doorways, non-smoking buildings and even full smoking bans on campus for some universities, these smoking limitations often only serve to protect non-smoking populations from exposure to second-hand smoke,” said Michael Waring, a co-author of the research.

At first, the researchers were simply studying how outdoor particles made their way indoors. The researchers used a non-smoking classroom to better understand this transport and composition of outdoor particles.

After finding a surprising amount of third-hand smoke chemicals in the room, the researchers shifted their focus to the transportation and transfer of these chemicals that attach to aerosol particles.

“In an empty classroom, where smoking has not been allowed in some time, we found that 29 percent of the entire indoor aerosol mass contained third-hand smoke chemical species,” said Anita Avery, a member of the research team. “This was obviously quite startling and raised many questions about how that much third-hand smoke could be lingering in a non-smoking, ventilated room.”

The researchers set up an experiment to simulate third-hand smoke exposure in a lab by first filling a Pyrex container with cigarette smoke. Next, the smoke was filtered out and outdoor air was pumped into the container.

After the outdoor air had circulated through the container, the researchers tested the chemical composition of aerosol particles in the container and compared these to measurements of outdoor air composition.  

Even though all the smoke had been cleared out, there was a 13 percent increase in third-hand smoke chemicals.

“What we’d actually uncovered was a new exposure route for third-hand smoke – through aerosol particles, which are ubiquitous in the indoor environment,” said Peter DeCarlo, a fellow author of the study.

The study highlights another way people can be exposed to pollutants like cigarette smoke even in non-smoking environments, and the researchers hope their findings will bring about new policies to limit exposure to dangerous third-hand smoke.

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By Kay Vandette, Earth.com Staff Writer