Secondhand marijuana smoke and kids

Claire McCarthy, MD

Senior Faculty Editor, Harvard Health Publishing

For years, we’ve talked about the danger to children of secondhand tobacco smoke. It makes asthma worse, increases the risk of respiratory and ear infections — and even increases the risk of sudden death in infants. We’ve had all sorts of educational campaigns for parents and caregivers, and have made some progress: between 2002 and 2015, smoking among parents of children less than 18 years old dropped from 27.6% to 20.2%. But now there is a new problem: secondhand marijuana smoke.

Studies show that when you are around someone who is smoking marijuana, the smoke gets into your system too. How much of it gets in depends on how close the person is, how many people are smoking and how much, how long you spend near them, and how much ventilation there is in the space. But research is clear that cannabinoids, the chemicals that cause the “high,” get into the bodies of people nearby — including children.

During the same time period that cigarette smoking around children came down more than 7%, marijuana smoking around children went up nearly 5%. With more and more states legalizing marijuana for recreational use, that number is likely to continue going up.

This is not good. Besides the fact that we don’t want children getting high, or exposed to the dangers of inhaled secondhand marijuana smoke, there is the additional concern about long-term effects on the brain. While research is still ongoing, there is evidence to suggest that when youth and young adults (whose brains are still developing) are exposed to marijuana, it may have permanent effects on executive function, memory, and even IQ.

This is not what we want for our children.

All the advice we give to parents who smoke tobacco applies to parents who smoke marijuana, including:

  • The best thing for you and your child is to not smoke at all. Talk to your doctor about ways to quit.
  • If you do smoke, don’t smoke around your child, ever.
  • Even if your child isn’t around, don’t smoke somewhere they will be, like your home or your car. Smoke lingers.
  • After you smoke, change your clothes and wash up. Again: smoke lingers.

As legal use of marijuana grows more common, we need to create the same kinds of rules and laws we’ve created to protect people from secondhand tobacco smoke.

Just because something is legal doesn’t mean it’s safe. And when we make choices that have risks, it’s not fair to impose those risks on other people — especially children, and especially when they could literally be harmed for the rest of their lives.

Follow me on Twitter @drClaire


  1. D

    What, if anything, can be done about neighbors who smoke? The smoke wafts down into my sister in law’s home. She has two very young children and is rightfully concerned.

  2. Donna Cooper

    All I know is if I’m a parent or pregnant I won’t do anything that “might” effect my child. Is smoking really that important?

  3. Ray

    I have a question about a mother who smokes marijuana and breastfeeds. Not necessarily smoking while nursing or in front of the child, but a breastfeeding mother who uses. I have a relative who smokes and is breastfeeding her baby and I often wonder what affect it might have, if any, on the child (i.e. anything crossing over in the breast milk to the baby?). I would appreciate your thoughts, or it would be great if a separate article could be written on the subject and any related research. Thanks.

  4. Brenda Paganelli

    My daughter has vitaligo. I’ve been advised that going gluten free reduces inflamation which causes vitaligo. Do you agree? Or suggest another diet?

  5. Charlie

    It’s a shame that with all that education, you’re still so misinformed about cannabis. That’s because you’ve been educated/ brainwashed by big Pharma. Instead of worrying about the non existent “dangers of secondhand marijuana smoke”, you should be worried about the over prescribing of antidepressants, anti anxieties, and anti psychotics to our kids. The poison big Pharma pumps into our children is the real danger to our children’s brains.

  6. Naveen

    Awesome post and straight to the point I don’t know if this in actually the best place to ask but do you people have any idea where to employees some professional writing?? Thanks advance

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