A man smoking a cigarette. REUTERS / Shailesh Andrade
A man smoking a cigarette. REUTERS / Shailesh Andrade

Even when you quit smoking, residue from cigarette smoke containing dangerous carcinogens can linger for as long as six months, according to a new study from San Diego State University.

Researchers have known for some time that “third-hand smoke,” as this leftover residue is known, sticks around in the environment long after the smoke has cleared, but little was known about what happens in the homes of smokers after they quit.

“It’s important to know how long third-hand smoke lingers in a home environment and if the former smoker and other residents are exposed to its toxic compounds,” explained Georg Matt, the study’s lead author and a psychology professor at SDSU.

Matt and colleagues recruited 90 smokers who said they planned to quit smoking. Over the course of six months, the researchers periodically visited their homes and took surface samples from walls and door panels, dust samples from the floor, and hand-wipe samples from the residents. They then analyzed those samples for the presence of a variety of tobacco-related chemicals such as nicotine, cotinine and the potent lung carcinogen known as NNK.

“The question we were trying to answer is, ‘How quickly does your home become truly smoke-free?’” Matt said. “You may have quit smoking and become a nonsmoker, but your home still carries the legacy of tobacco smoke.”

Within those homes that managed to go smoke-free for the full six months of the study, the home surfaces and residents’ fingers showed an immediate, significant drop-off in nicotine soon after cessation. But, as reported Wednesday in the journal Tobacco Control, that decline leveled off and remained at higher-than-normal levels for the remainder of the study.

More worrisome is that in the dust samples, the levels of nicotine and NNK remained virtually unchanged, even after six months without smoking.

“Thirdhand smoke consists of gases and ultra-fine particles that go deep into the carpet, upholstery and fabrics, and they even penetrate deep into walls and furniture,” Matt said. “Tobacco smoke does not simply disappear. Smoking indoors builds up a reservoir of chemicals that leaves a long and toxic legacy of tobacco use.”

That legacy might even be part of the reason it’s so hard to quit smoking, he added. One consequence of third-hand smoke is lingering odor, and there’s good reason to think that constantly being reminded through your nose of the habit you’re trying to kick makes cravings for cigarettes stronger and quitting especially difficult.

Chris Jennewein

Chris Jennewein is Editor & Publisher of Times of San Diego.