Addiction Nicotine Use The Inside of Cigarettes Why You Should Stay Away From Thirdhand Smoke By Terry Martin Terry Martin Facebook Twitter Terry Martin quit smoking after 26 years and is now an advocate for those seeking freedom from nicotine addiction. Learn about our editorial process Updated on October 11, 2021 Medically reviewed Verywell Mind articles are reviewed by board-certified physicians and mental healthcare professionals. Medical Reviewers confirm the content is thorough and accurate, reflecting the latest evidence-based research. Content is reviewed before publication and upon substantial updates. Learn more. by Armeen Poor, MD Medically reviewed by Armeen Poor, MD Armeen Poor, MD, is a board-certified pulmonologist and intensivist. He specializes in pulmonary health, critical care, and sleep medicine. Learn about our Medical Review Board Print Megumi Kurosaki / Getty Images Thirdhand smoke (THS) is a term originally coined by doctors at Massachusetts General Hospital for Children. Meant to describe dangers specifically associated with residual toxins left behind on surfaces once firsthand and secondhand smoke have cleared out of a room, we now understand more about the composition of THS that lingers in the air, as well. What Is Thirdhand Smoke? Have you ever stood in a check-out line and could tell that someone in line had been smoking, even though you didn't see them do it? Or maybe you walked into a room thick with the unmistakable smell of stale cigarette smoke, even though there was no visible smoke in the room? Or, if someone smokes in your house or car, how about that yellow gunk you clean off the windows? These are all examples of what is known as THS, a noxious mix of gases and small particles that remain in the air for hours after a cigarette is smoked, and are deposited on every surface they come into contact with. From air to hair, clothing, bedding, furniture, carpets, table surfaces and toys, nothing is exempt from contamination if it's in a room or other closed environment (like a vehicle) where cigarettes were smoked. The Differences Between First, Second, and Thirdhand Smoke So, what is the difference between firsthand smoke, secondhand smoke, and thirdhand smoke? Firsthand smoke is cigarette smoke that a person draws into their lungs when inhaling from a lit cigarette. Secondhand smoke is a combination of exhaled firsthand smoke and the smoke wafting into the air from the end of a burning cigarette. Thirdhand smoke can be broken down into three distinct parts: Gases and small particles that are suspended for hours in the air of rooms or other closed spaces (aged secondhand smoke).Tiny solid particles that settle and stick to surfaces of an enclosed area.Toxins on surfaces and in the air that combine with other common indoor pollutants, creating new chemical compounds or more dangerous forms of chemicals in the process. Thirdhand Smoke in the Air Scientists have discovered that aging secondhand smoke hanging in the air of an enclosed space changes over time in unexpected ways. While most of the solid particles in THS fall to surfaces within 20 minutes, some solid matter does remain in the air and can be inhaled into the lungs. Additionally, the levels of some chemicals in secondhand smoke actually increase for a time as the smoke transitions to THS, making breathable air in a room more dangerous. Three toxic chemicals of this type that have been identified are acrolein, methacrolein, and acrylonitrile. The first two are respiratory and eye irritants, and the third, a highly flammable carcinogenic compound. Thirdhand Smoke on Surfaces Nicotine and other toxins from cigarette smoke coat everything it comes in contact with. And worse, some of those chemicals are transformed when they come into contact with other common indoor pollutants. For instance, when nicotine reacts with nitrous acid on indoor surfaces, it creates TSNAs, a group of highly carcinogenic chemicals. Chemicals from THS also stay in the environment for a long time. Research has shown that rooms that were smoked in retain THS in dust and on surfaces long after smoking has ceased. It even persists after cleaning and repainting. Thirdhand Smoke in Chemical Fumes Researchers have learned that some of THS toxins parked on surfaces can off-gas, meaning that chemical fumes are released back into the air from the solid particles in that residue. Other Dangers Scientists have learned that when ozone mixes with residual nicotine in the air and on surfaces, it transforms into ultra-fine particles that can be inhaled deep into the lungs. These particles may be difficult for the body to expel and could cause additional breathing problems for asthma sufferers. Thirdhand Smoke Risks for Children The chemical fallout that settles on surfaces from the gases and small particles in cigarette smoke isn't good for anyone to be exposed to, but it's especially harmful to small children. They are much more likely to ingest these invisible toxins when touching furniture, floors, and toys because they put their fingers (and toys, etc) in their mouths often. It should also be noted that THS in the air is a greater risk for babies and young children, too, because their respiratory rate is faster. This causes them to inhale more toxins in the same amount of time as someone who is older with a slower rate of breathing. Bottom Line We've known for a long time that cigarette smoke is dangerous air to breathe. Now we also know that secondhand smoke lingers, settles and even transforms into other dangerous chemicals known as thirdhand smoke. It is important for your health and those you care about to avoid indoor areas where smoking is allowed. If you have people who smoke in your family, set a strict boundary about smoking outside. Researchers have identified more than 7,000 different chemical compounds that are present in cigarette smoke, including at least 250 poisonous gases, at least 69 carcinogens, and several heavy, toxic metals. Do your part to ensure that children don't suffer the health hazards posed by cigarette smoking. Ban smoking in your home and car, and if you smoke, quit now 6 Sources Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Matt GE, Quintana PJ, Zakarian JM, et al. When smokers move out and non-smokers move in: residential thirdhand smoke pollution and exposure. Tob Control. 2011;20(1):e1. doi:10.1136/tc.2010.037382 Sleiman M, Logue JM, Luo W, Pankow JF, Gundel LA, Destaillats H. Inhalable constituents of thirdhand tobacco smoke: chemical characterization and health impact considerations. Environ Sci Technol. 2014;48(22):13093-101. doi:10.1021/es5036333 Jacob P, Benowitz NL, Destaillats H, et al. Thirdhand Smoke: New Evidence, Challenges, and Future Directions. Chem Res Toxicol. 2017;30(1):270-294. doi:10.1021/acs.chemrestox.6b00343 Sleiman M, Destaillats H, et al. Secondary organic aerosol formation from ozone-initiated reactions with nicotine and secondhand tobacco smoke. Atmospheric Environment. 2010;(44)34:4191-4198. doi:10.1016/j.atmosenv.2010.07.023Get Secondhand Smoke. Nationwide Children’s Hospital. Harms of Cigarette Smoking and Health Benefits of Quitting. National Institutes of Health. December 2017. Additional Reading Thirdhand Smoke: Toxic Airborne Pollutants Linger Long After the Smoke Clears. University of California, Berkeley. Third-Hand Smoke: Another Reason to Quit Smoking. 29 December, 2008. EurekAlert - American Associateion for the Advancement of Science (AAAS). Berkeley Study Shows Ozone and Nicotine a Bad Combination for Asthma. University of California, Berkeley. Formation of Carcinogens Indoors By Surface-mediated Reactions of Nicotine With Nitrous Acid, Leading to Potential Thirdhand Smoke Hazards. National Institutes of Health. U.S. National Library of Medicine. When Smokers Move Out and Non-smokers Move In: Residential Thirdhand Smoke Pollution and Exposure. National Institutes of Health. U.S. National Library of Medicine. Inhalable Constituents of Thirdhand Tobacco Smoke: Chemical Characterization and Health Impact Considerations. Environmental Science and Technology. Thirdhand Smoke Identified as Potent, Enduring Carcinogen. Wiley Online Library. By Terry Martin Terry Martin quit smoking after 26 years and is now an advocate for those seeking freedom from nicotine addiction. See Our Editorial Process Meet Our Review Board Share Feedback Was this page helpful? Thanks for your feedback! What is your feedback? Other Helpful Report an Error Submit Get Treatment for Addiction Advertiser Disclosure × The offers that appear in this table are from partnerships from which Verywell Mind receives compensation.