Dusty air.

Researchers identify main factors of home indoor air pollution: marijuana surprisingly plays a big role

A new study led by San Diego State University researchers has identified the most important factors that go into home indoor air pollution. Tobacco and marijuana smoking turned out to be some of the biggest offender — marking the first time the drug was found to play such a role.

Dusty air.

The researcher’s main goal was to understand what behaviors lead to an increase in airborne particle densities in homes, leading to unhealthy or even hazardous environments for kids. So the team, led by SDSU environmental health scientist and lead author Neil Klepeis, worked with almost 300 families living in San Diego which had at least one child aged 14 or younger and one or more smokers.

Each home had a pair of air particle monitors installed — one as close to the area where the families reported smoking as possible while still being indoors, and one in the child’s bedroom. These sensors could pick up particles between 0.5 and 0.25 micrometers in size, the diameter that includes dust, spores, combustion byproducts as well as auto exhaust. These particles can have a nasty effect on health since they’re small enough to reach deep into the lungs and can cause a wide range of lung and cardiovascular issues.

Out of the total, 44 (22.8%) of families reported at least one household member smoking at least one cigarette indoors in the 7-days prior to the interview. Homes without indoor cigarette smoking reported indoor smoking of cigars (1.3%), hookah (0.8%), electronic cigarettes (14.1%), marijuana (10.1%), and other drugs (0.7%). Nearly all families reported opening a window (95.3%) or opening a door (96.9%) for ventilation purposes. Most homes (60.1%) reported using an exhaust fan in their kitchen and 8.3% of homes used an air purifier. No significant differences in ventilation activities were seen between homes with indoor and outdoor smoking, except the use of central air conditioning which was higher among homes without indoor cigarette smoking (25.5% vs. 6.8%).

On average, the homes had 2.6 bedrooms, 1.6 bathrooms and were mostly one story.  The team notes that “with the exception of the number of doors leading outside, none of the home characteristics of families with and without self-reported indoor cigarette smoking differed significantly.”

Up in smoke


The monitors worked continuously for three months, feeding air quality data to the researchers.The team also carried out two sessions of interviews with each family to ask about their schedule to get an idea of what activities were likely to occur in the house at various times, especially cooking, cleaning, and smoking, as these tend to generate said particles.

Families that reported smoking cigarettes indoors had an average particle level almost double that of non-indoor-smoking families. These particles included nicotine and combustion byproducts, both linked to health issues especially for children. Surprisingly enough, marijuana smoking contributed to in-home air pollution about as much as tobacco smoking. Burning candles or incense, frying food in oil, and spraying cleaning products also led to an increase in the number of fine particles.

“The aim of our research is, ultimately, to find effective ways to promote smoke-free homes and also to find good strategies, in general, for reducing exposure to household pollution,” Klepeis said in a press release. “The findings from our work will allow for better education and feedback to families.”

The team plans to expand on the marijuana findings to see whether the rise in indoor pollution resulting from its use translates into increased exposure to combustion byproducts and cannabinoids in nonsmokers living in the house.

In the meantime, if you’re worried about the quality of air in your home or simply want to tidy it up a bit, here’s a handy guide by NASA to decide what plants to get. They also look pretty, and green, and will make you feel better. Win-win-win!

The full paper “Fine particles in homes of predominantly low-income families with children and smokers: Key physical and behavioral determinants to inform indoor-air-quality interventions” has been published in the journal PLOS One.

10 thoughts on “Researchers identify main factors of home indoor air pollution: marijuana surprisingly plays a big role

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  4. Brian

    Where did the prohibition funding for this study come from again?
    Smoking pot does not increase lung problems or cause lung cancer. So the particles are not harmful. Are skin cell harmful? nope. Because humans digest or expel them. Our skin cells are the majority of dust in most homes.

  5. Alex Micu

    The difference in substance is what counts, not the size. Ash is hard, brittle, and breaks with an edge. Skin cells are flappy at their worst. So ash can cut alveola and other tissue.

  6. Brian

    Thank you for the reference on funding. The pint is that pot smoking and smoke have not been found to be harmfully and they have tried, and pot smoking reduces cancer risks. So there is no reason to believe airborne pot smoke would be bad in any way. This study did not differentiate between types of dust that were harmful and just assumed all were.
    Tobacco and nicotine are known carcinogens, and nicotine used in pesticides. Yet this study counted every particle as equally bad.

    Thanks for the pics too, but they alone don't counter the relative safety of pot smoke. For that matter do we even know if inhaling skin dust is bad for us or not?

    I would like to see more details on who funds these researchers and the group, not just this study.

  7. Alex Micu

    Well I was once digging into the whole tobacco/pot smoke health effects — for a friend of course — and don't quote me on this but I recall that while pot smoke was easier on the lungs compared to tobacco smoke, those who smoked both tended to see the worst overall damage to their lungs.

    Then again this study only reports that both marijuana and tobacco smoking led to an increase in airborne particles — which seems sensible given the fact that something was burning in the house — and doesn't make any assumption regarding each particle type's particular effect on health — just referencing the fact that particles of this caliber are known to cause health problems in general, since they can end up deep in the lungs.

    Lastly I'd point out that not-cancer-causing isn't the same thing as non-particle-releasing. I'd imagine burning 1 ounce of hay or 1 ounce of mint or 1 ounce of tobacco/pot would release a comparable amount of airborne particles.

  8. Brian

    Sorry, the consensus is that pot smoking is not bad for you lungs. search pot smoking good for your lungs Even with the few prohibition paid nonsense studies, it's pretty clear it not bad for you.

    Again. do skin cells cause lung problems?

    Sure, if you smoke bad weed full of paraquat, you probably will have problems. Good clean pot, particularly in a bong, the research is very much for it being good for you, rather than bad.

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