Health figures follow CDC and U.S. Surgeon General reports. Prices and ratings were checked on Amazon on October 10, 2026. This guide is general information, not medical advice.
Secondhand smoke is also called environmental tobacco smoke. It is the mix of two kinds of smoke from tobacco. When someone in the home smokes, it is hard to avoid. Even when that person smokes outside, the smell and the residue come back in on their clothes, hair and hands.
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The Two Kinds of Secondhand Smoke
Sidestream smoke comes from the burning end of a cigarette, pipe or cigar. It rises from the tip whether or not anyone is puffing. It has higher concentrations of some toxic compounds than the smoke a smoker inhales, including carbon monoxide, ammonia and benzene. The particles are small, and they can travel deep into the lungs.
Mainstream smoke is the smoke a smoker breathes out. It is thinner than sidestream smoke, but it still carries a mix of carcinogens and toxins. It lingers in a room long after the cigarette is out. Our guide on smoking indoors and smell shows how far it spreads.
Why Is Tobacco Smoke a Problem?
Secondhand smoke holds more than 7,000 chemicals. Hundreds are toxic, and about 70 are known to cause cancer. Among them are formaldehyde, benzene, arsenic and cyanide compounds, found in small amounts.
Health effects for non-smokers
- Adults: a higher risk of heart disease, stroke and lung cancer. The CDC puts the extra risk at around 25 to 30 percent for heart disease and 20 to 30 percent for lung cancer.
- Babies and children: a higher risk of sudden infant death syndrome (SIDS), ear infections, more asthma attacks, and more colds, bronchitis and pneumonia.
- Pregnancy: exposure is linked to lower birth weight.
- People with asthma or lung disease: more wheezing, coughing and flare-ups.
The CDC estimates that secondhand smoke causes tens of thousands of deaths each year among non-smoking adults in the United States, plus several hundred infant deaths. The U.S. Surgeon General has concluded that there is no risk-free level. Learn more about the lung effects in our guide to asthma symptoms and management.
Looking ahead, smoke-free rules keep spreading, from apartment buildings to public housing and parks, and fewer adults smoke than a generation ago. The catch is that the smoke is not disappearing so much as changing shape. Cannabis smoke and vape clouds now share the same walls, and cheap purifiers sold for “smoke” rarely say which kind they mean.
Where Is Secondhand Smoke a Problem?
Home
The home is the most overlooked place. Children in smoking homes get the most exposure, and it affects pets too. Smoke also drifts between apartments through walls, vents and shared hallways.
Vehicles
A car is a small box. Smoke levels inside can climb fast, even with a window cracked, and the residue sticks to seats and fabric.
Workplaces
Many places now ban indoor smoking, but poorly vented smoking areas and doorways still expose staff and visitors.
Public places
Parks, patios, sidewalks and building entrances can all see drifting smoke. Rules and enforcement vary by city.
What About Thirdhand Smoke?
Smoke does not just float away. It leaves a sticky film on walls, floors, furniture and dust, called thirdhand smoke. It can build up for years and release chemicals back into the air. Young children who crawl and touch things get the most exposure. Washing and repainting help, and a purifier slows the buildup of airborne smoke, but it will not strip residue from surfaces. Our guide on getting smoke smell out of a house covers the cleanup.
What About Pets?
Pets live close to the floor, where smoke residue settles, and they lick it off their fur. Studies have linked secondhand smoke to eye and lung problems in cats and dogs, and to some cancers in cats. Small birds are very sensitive to smoke. If you smoke, a smoke-free home is good for them too.
How to Set Smoke-Free Rules at Home
- Be clear and kind. Say it once, plainly: no smoking or vaping inside, in the garage or in the car.
- Give a plan, not just a ban. Point to a spot well away from windows and doors, and offer help to quit.
- Wash up after. Smoking outside, then touching a baby or a couch, still carries residue indoors. Changing a jacket and washing hands helps.
- Keep guests informed. A short sign near the door saves awkward talks.
Renting Near a Smoker
Smoke moves through shared walls, vents and gaps around pipes. Start by sealing what you can: door sweeps, outlet covers and caulk around pipes. Ask the landlord about smoke-free building rules, and keep a log of dates and times if smoke keeps coming in. Add a purifier in the room where you sleep. Our guide on indoor air quality for landlords and renters covers your options.
What Can Be Done About Secondhand Smoke?
- Make home and car smoke-free. This is the only step that removes the exposure. Ask visitors to smoke well away from the house, and not in the garage or by a window.
- Get help to quit. In the United States, call 1-800-QUIT-NOW for free coaching, or visit smokefree.gov. Combining counseling with approved quit medicine works better than willpower alone. Ask a doctor which medicine fits you.
- Do not swap to vaping and call it solved. Vapor from e-cigarettes is an aerosol that can contain nicotine and fine particles. It is not harmless air.
- Choose smoke-free restaurants, rentals and workplaces.
- Teach children to walk away from smoke, and talk to relatives about smoke-free visits.
- If smoke drifts in from a neighbor or a coworker, seal gaps around doors, outlets and pipes, and add an air purifier. See the next section.
The risk to watch is leftover smoke. Tobacco residue sticks to walls, carpet and dust, and it can linger for months in a home where someone used to smoke. That is called thirdhand smoke. Expect more renters and buyers to ask about it, and do not expect a purifier to remove it from surfaces.
Do Air Purifiers Help With Secondhand Smoke?
They help, but with limits. A true HEPA filter captures the tiny particles in smoke. A thick activated carbon filter holds onto much of the smell and some of the gases. Together they can cut the amount of smoke you breathe, especially in a closed room. That is useful if smoke drifts in from outside the home.
The limits are real, though. The U.S. Surgeon General has said that cleaning the air and ventilating cannot fully remove the health risk from secondhand smoke. A purifier does not remove carbon monoxide, and it does not clean the film on surfaces. If someone smokes inside, the purifier is trying to keep up with a source that never stops. Use it as a backup, never as the plan.
Look for a smoke CADR that fits the room. The CADR calculator and our guide to the best air purifiers for smoke show how. Prices and ratings below were checked on Amazon on October 10, 2026.
Price on Amazon: $179.99 | 4.6 stars from 32,377 ratings (checked October 10, 2026)
The Winix 5510 is a good value for a living room, with true HEPA and a thick carbon filter for smoke odor.
Price on Amazon: $229.99 | 4.6 stars from 29,196 ratings (checked October 10, 2026)
The Coway Mighty adds an air quality light that shows when smoke is in the room, and a filter indicator.
Price on Amazon: $610.00 | 4.3 stars from 102 ratings (checked October 10, 2026)
The Austin Air HealthMate Junior uses a deep bed of carbon and zeolite built for odors and chemical gases, with a filter life the maker rates at up to five years. It costs a lot more, and it covers a smaller area.
Price on Amazon: $845.00 | 4.3 stars from 239 ratings (checked October 10, 2026)
The Austin Air HealthMate Standard is the same filter bed in a larger cabinet for bigger rooms. On a tight budget, look at air purifiers for smoke under $100. If the smoke is from cannabis, see our guide to air purifiers for weed smoke.
Final Word
Secondhand smoke is not a smell problem. It is a health problem, and the only truly safe level is none. Start with a smoke-free home and car, get help to quit if someone is smoking, and use a purifier for what drifts in. For more on picking one, see air purifiers for smoke and odors.
What happens next: more landlords will write smoke-free clauses into leases, and more families will have a clear way to ask for a smoke-free home. A purifier is a fine backup when smoke drifts in from next door. It is not a license to smoke indoors, and it never makes smoke safe.
Related Guides
Keep going with best air purifiers for smoke, air purifiers for smoke and odors, indoor air quality for landlords and renters and CADR calculator.
