A new study has found that fewer parents with children at home are smoking cigarettes, while cannabis use is up. Additionally, parents who smoke cigarettes are much more likely to also use cannabis than their non-tobacco-using counterparts.

The study comes out of joint project between Columbia University's Mailman School of Public Health and City University of New York. The researchers analyzed data collected by the National Survey on Drug Use and Health between 2002 and 2015. While they found that the overall number of parents with children in the home who smoke tobacco or marijuana dropped from 30% down to 24%, parents that do smoke cannabis are on the rise while tobacco is becoming less popular.

Cannabis use increased from 5% to 7% and tobacco use declined from 28% to 20%. Parents who smoke tobacco were 4 times as likely to also consume cannabis as parents who do not.

And, as Dr. Renee Goodwin of the Department of Epidemiology at the Mailman School of Public Health says, the study suggests that efforts to reduce childhood exposure to secondhand tobacco smoke seem to be working, but the results are complicated by the rise in cannabis use.

"The results of our study support the public health gains in reducing overall child secondhand tobacco smoke but raise other public health concerns about child exposure to secondhand cannabis smoke and especially high risk for combined exposures in certain subpopulations," says Goodwin.

Of course, as cannabis becomes increasingly normalized across the country cannabis use is likely to continue to rise. And while consuming marijuana can be an effective means of unwinding for stressed-out parents, there are still a number of ongoing concerns with regards to secondhand smoke. Hopefully, as cannabis legalization rolls out, parents will be able to move their cannabis smoking outside of the home, creating a healthier environment for both parents and children.