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  2. Indoor Air Quality (IAQ)

Secondhand Marijuana Smoke and Indoor Air Quality

On this page:

  • What is Secondhand Marijuana Smoke?
  • What are the Health Effects of Secondhand Marijuana Smoke?
  • What Can I Do to Reduce Exposure to Secondhand Marijuana Smoke?

Related pages:

  • Secondhand Smoke and Electronic-Cigarette Aerosols
  • Secondhand Tobacco Smoke and Indoor Air Quality
  • Secondhand Electronic-Cigarette Aerosol and Indoor Air Quality
  • Secondhand Smoke and Electronic-Cigarette Aerosol Resources

image of cannabis buds and rolled cannabis cigarettes

What is Secondhand Marijuana Smoke?

Secondhand marijuana smoke is a mixture of the smoke given off by a burning marijuana product and the smoke exhaled by a smoker. Marijuana can also be used in electronic cigarettes and other devices, which emits an aerosol.

The components of marijuana smoke may vary depending on several factors, including the species of plant, how it is grown, and how it is used. 


What are the Health Effects of Secondhand Marijuana Smoke?

According to the Centers for Disease Control and Prevention, the known risks of secondhand exposure to tobacco smoke — including risks to the heart and lungs — raise concerns that secondhand exposure to marijuana smoke may cause 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.

More research is needed to better understand marijuana smoke and secondhand marijuana smoke.

  • Learn more about secondhand marijuana smoke from the CDC. 
  • Learn more about marijuana’s risks from the Substance Abuse and Mental Health Services Administration. 

What Can I Do to Reduce Exposure to Secondhand Marijuana Smoke?

Prohibiting marijuana smoking inside or near buildings, vehicles and other enclosed spaces is the only way to eliminate secondhand exposures and health risks that may come with it.

Secondhand marijuana smoke can expose bystanders to potentially harmful substances.

Ventilation, filtration and air cleaning techniques can reduce harmful substances released from marijuana use indoors but are not likely to eliminate them.

If you smoke marijuana and want to quit, resources are available.

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Last updated on May 13, 2025
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