Secondhand Marijuana Smoke

The known risks of secondhand exposure to tobacco smoke—including risks to the heart and lungs1—raise questions about whether secondhand exposure to marijuana smoke causes similar health risks. Secondhand marijuana smoke contains many of the same toxic and cancer-causing chemicals found in tobacco smoke and contains some of those chemicals in higher amounts.2

Secondhand marijuana smoke also contains tetrahydrocannabinol (THC), the compound responsible for most of marijuana’s psychoactive effects (or the “high”). THC can be passed to infants and children through secondhand smoke, and people exposed to secondhand marijuana smoke can experience psychoactive effects, such as feeling high.3,4 Recent studies have found strong associations between reports of having someone in the home who uses marijuana (e.g., a parent, relative, or caretaker) and the child having detectable levels of THC.5,6 Children exposed to THC are potentially at risk for negative health effects. More research is needed to understand how secondhand marijuana exposure may affect children. Other research shows that marijuana use during adolescence can impact the developing teenage brain and cause problems with attention, motivation, and memory.6 To learn more about the long-term effects of marijuana use, please visit the health effects section.

More research about the effects of marijuana secondhand smoke is still needed.

  1. Alberg AJ, Shopland DR, Cummings KM. The 2014 Surgeon General’s report: commemorating the 50th Anniversary of the 1964 Report of the Advisory Committee to the US Surgeon General and updating the evidence on the health consequences of cigarette smokingexternal icon. American Journal of Epidemiology. 2014;179(4):403-412.
  2. 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.external icon Chemical Research in Toxicology. 2008;21(2):494-502.
  3. Taylor DR, Poulton R, Moffitt TE, Ramankutty P, Sears MR. The respiratory effects of cannabis dependence in young adults. Addiction. 2000;95(11):1669-1677.
  4. Wilson KM, Torok MR, Wei B, et al. Detecting biomarkers of secondhand marijuana smoke in young children. Pediatric Research. 2017;81(4):589-592.
  5. Moore C, Coulter C, Uges D, et al. Cannabinoids in oral fluid following passive exposure to marijuana smoke. Forensic Science International. 2011;212(1-3):227-230.
  6. Broyd SJ, van Hell HH, Beale C, Yuecel M, Solowij N. Acute and chronic effects of cannabinoids on human cognition—a systematic review. Biological Psychiatry. 2016;79(7):557-567.