The Short Answer
Thirdhand smoke is the chemicals left behind when someone smokes tobacco. Thirdhand smoke is unhealthy for people and pets. It can stick around for a long time in homes and cars. It gets into your body if you inhale, swallow, or touch the chemicals. Getting rid of it is really hard and can cost a lot of money.
Similar to tobacco smoke, cannabis smoke comes from burning plant material. Current studies suggest that cannabis smoke sticks to surfaces, collects in dust, and absorbs into materials. Cannabis and tobacco smoke residue have some of the same toxic chemicals that are dangerous to breathe in, touch, or ingest. The aerosols from nicotine and cannabis vapes also create a similar residue that remains on surfaces and in dust.
The Long Answer
Thirdhand smoke is the chemical residue from tobacco smoke. It is also called “tobacco smoke residue” or “stale tobacco smoke.” The chemicals in thirdhand smoke are toxic to humans, especially children. Thirdhand smoke can linger for years in dust and on household surfaces. It can also become embedded in carpets, furniture, clothes, and building materials. It is difficult and expensive to remove.
Cannabis smoke is a newer area of study for scientists. Current studies suggest that smoking or vaping cannabis leaves behind a thirdhand chemical residue that is similar to the residue from smoking or vaping tobacco products. The thirdhand chemical residue from cannabis has some of the same cancer-causing chemicals as the residue from tobacco.
THC is the active ingredient in cannabis that produces the “high.” In rooms where cannabis has been smoked or vaped, THC accumulates on surfaces, collects in dust, and soaks into materials. Although exposure to cannabis-related thirdhand chemical residue will not get someone “high,” the residue contains many toxic chemicals that are dangerous to breathe in, touch, or ingest.
Do you have more questions about the toxic legacy of tobacco smoke, how it affects human health, and what we can do about it? Learn more here.
Updated: May 2025
Sources:
Huang AS, Murphy MBC, Jacob P, et al. PM2.5 concentrations in the smoking lounge of a cannabis store. Environmental Science & Technology Letters, 2022; 9(6):551–556. doi: 10.1021/acs.estlett.2c00148
Moir D, Rickert WS, Levasseur G, et al. A comparison of mainstream and sidestream marijuana and tobacco cigarette smoke produced under two machine smoking conditions. Chemical Research in Technology. 2008;21(2):494-502. doi: 10.1021/tx700275p
Sempio C, Lindley E, Klawitter J, et al. Surface detection of THC attributable to vaporizer use in the indoor environment. Scientific Reports. 2019;9(1):18587. doi: 10.1038/s41598-019-55151-5
Tang X, Cancelada L, Rapp VH, et al. Emissions from heated terpenoids present in vaporizable cannabis concentrates. Environmental & Science Technology. 2021;55(9):6160–70. doi: 10.1021/acs.est.1c00351
Wylie ADL, Abbatt JPD. Heterogeneous ozonolysis of tetrahydrocannabinol: Implications for thirdhand cannabis smoke. Environmental & Science Technology. 2020;54(22):14215–23. doi: 10.1021/acs.est.0c03728
Yeh K, Li L, Wania F, et al. Thirdhand smoke from tobacco, e-cigarettes, cannabis, methamphetamine and cocaine: Partitioning, reactive fate, and human exposure in indoor environments. Environment International, 2022;160:107063. doi: 10.1016/j.envint.2021.107063
