The prevalence of asthma is on the rise among adolescents in states that have legalized cannabis for recreational use, relative to states that remain fully illegal, according to a new study at Columbia University Mailman School of Public Health and The City University of New York. 

The results, published online in the journal Preventive Medicine, provide early evidence that legalizing and commercializing adult cannabis use may be related to a potential rise in asthma prevalence. 

The study, which also observed increases in asthma among children in some minority racial and ethnic groups in states with recreational legalization, is the first to examine the relationship between changes in cannabis policy for adult use and asthma prevalence among children and adolescents. 

“Our findings suggest that state-level cannabis policy could have downstream impacts on children’s respiratory health,” says Renee D. Goodwin, PhD, adjunct associate professor in the Department of Epidemiology at Columbia Mailman School of Public Health and professor at The City University of New York, in a press release. “Cannabis use is increasing among adults with children in the home, particularly in states which have legalized for medical or recreational use. Exposure to secondhand smoke is a key risk factor for asthma among children. This study offers a critical first step in identifying a key children’s health concern emerging in the context of rapid, ongoing changes in cannabis policy that are unaccompanied by clinical or public health guidelines for parents.”

The researchers used data from the 2011-2019 National Survey on Children’s Health, a representative sample of the physical and mental health of non-institutionalized children in the US ages 0-17 years old.

Nationally, a statistically significant decrease in the prevalence of pediatric asthma was reported from 2011-2012 to 2016-2017, with no decline thereafter. Relative to states where cannabis was fully illegal, the prevalence of asthma increased slightly among adolescents 12-17 years old and among children identifying with non-Hispanic minoritized race and ethnic groups in states where cannabis was legal for adult recreational use.

“We believe that more research is urgently needed to estimate the potential consequences of increased adult use of cannabis in the community for children’s respiratory health and that this work should come before, or at least be done contemporaneously with, the widespread commercialization of cannabis for adult use in US states,” says Goodwin in the release.