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.