What is Thirdhand Smoke?

You’re probably well aware of the more widely researched health effects of secondhand smoke (i.e., “passive smoking”) which has led to a patchwork of laws that ban indoor smoking in government buildings, hospitals, bars, restaurants, and public transportation.

Another threat is the residual nicotine and other toxic brew of chemicals left by tobacco smoke long after the smoke—and maybe even its smell—have left an indoor environment.

You may never have heard of thirdhand smoke, but chances are you’ve smelled it.

What is Thirdhand Smoke?

As defined by the International Journal of Environmental Research and Public Health, thirdhand smoke (THS) is:

“…residual tobacco smoke that clings to indoor surfaces, and re-emission of gases and resuspension of particles from contaminated surface materials after active smoking has ceased. These are gases and particles, which become embedded in materials from walls to furniture to toys & other household items. Importantly, these residual substances can react, re-emit, and/or resuspend in an environment long after active smoking has ended.”

According to the Mayo Clinic, the residue is thought to react with common indoor pollutants to create a toxic mix including cancer causing compounds, posing a potential health hazard to nonsmokers—especially children.

What are the Dangers of Thirdhand Smoke?

Thirdhand smoke poses complex research challenges and a broad array of potential harms from the smoke residues, including an increasing risk of cardiovascular diseases and cancers, changes to DNA, asthma and other respiratory diseases, and impaired wound healing.

Layers of these invisible cigarette-smoke residues can build up on surfaces and sink deep into rugs, draperies, and upholstered furniture. Even when smokers never smoke inside the home, smoke residues can persist on their hair and clothing, and spread to surfaces inside their homes.  

Thirdhand smoke poses the greatest threat to infants and children, who inhale particles suspended in the air or ingest the residues when they touch and crawl on contaminated surfaces, then put their fingers into their mouths.

Can you get rid of Thirdhand Smoke?

Although the only long-term fix for thirdhand smoke pollution is not smoking, San Diego State University psychologist and researcher Georg Matt offers these tips for reducing your risk:

• Don’t actively smoke or use electronic cigarettes in the home or car.
• If you have visitors who smoke or use electronic cigarettes, ask them not to smoke indoors.
• If you visit family and friends who smoke indoors, stay overnight in a smoke-free hotel.
• Insist that visitors do not smoke or use electronic cigarettes in the presence of children.
• Request that smokers wash their hands and, if possible, change their clothes after smoking.
• If you rent a car, insist on a smoke-free vehicle. Reject any car that smells of smoke.
• When staying at hotels, request smoke-free rooms and decline any room that smells of smoke. Whenever possible, try to find hotels that are 100-percent smoke-free.
• When you rent your next apartment or buy your next home, make sure to ask about tobacco use.  Stay away from apartments and houses where former residents smoked.

Also, consider not buying or accepting second-hand upholstered furniture, rugs, mattresses, curtains, or pillows, unless you know they came from non-smoking indoor environments.

A fact sheet from the Respiratory Health Association describes the predicament of trying to rid an environment of thirdhand smoke:

“Simply cleaning does not completely remove thirdhand smoke contaminants from a room. Tests have found measurable levels of nicotine in new residents of formerly-smoking homes and hotel rooms – even after the unit has been professionally cleaned and left unoccupied for months! In such properties, it may be necessary to replace carpeting, wall boards, counters, and furnishings to completely eliminate exposure to tobacco-specific toxins/carcinogens. Additionally, new owners or renters of formerly-smoking homes should be given notice of the home’s former smoking status.”

Unfortunately, the current advice to throw out carpeting, upholstered furniture, repaint or even replace drywall, or move to a space where people have never smoked isn’t practical or possible for most Americans.

A Hazy Picture

The many questions still surrounding the health consequences of thirdhand smoke, and ways to eliminate it from areas where it has collected, have led some social scientists to urge restraint in creating new laws or recommendations from health professionals.

Until research develops a more definitive understanding of thirdhand smoke—its prevention, its harms, reliable ways to eliminate it—we can all take steps to reduce our exposure as much as possible.

Further reading

• Thirdhand Smoke: A Select Bibliography of Recent Studies
• The Hidden Hazard of Third Hand Smoke
• Thirdhand Smoke—The Unseen Danger
• Thirdhand Smoke Identified as Potent, Enduring Carcinogen
• Environmental Tobacco Smoke and Cardiovascular Disease
• Does the Smoke Ever Really Clear? Thirdhand Smoke Exposure Raises New Concerns
• Maps/Lists of Smoke-free areas 

Many Almanac readers use our Best Days to Stop Smoking. We say, whatever works for you!