Marijuana use augmented among parents who smoke cigarettes, as well as among non-smoking parents. Marijuana use was nearly four times more common among cigarette smokers compared with non-smokers. Until now, little had been known about current trends in the use of marijuana among parents with children in the home, the occurrence of exposure to both tobacco and cannabis, and which populations might be at greatest risk.

While use of either cigarettes or marijuana in homes with children has declined, there was a rise in the percent of homes with both. Therefore, the growth in marijuana use may be compromising progress in curbing exposure to secondhand smoke.

Marijuana use was also more predominant among men who also smoked compared to women (10 percent versus 6 percent) and among younger parents with children in the home (11 percent) compared with those 50 and older (4 percent). The strength of the association between current marijuana use and cigarette smoking was significant and similar for all income levels.

The results of the study support the public health gains in dropping overall child secondhand tobacco smoke but raise other public health anxieties about child exposure to secondhand marijuana smoke and especially high risk for joint exposures in certain subpopulations.

Noteworthy is that there remains a lack of info on the location of smoking, whether it occurs in the house or in the proximity of children. Unlike cigarettes, smoking marijuana outdoors and in a range of public areas is illegal in most places. Consequently, there is motive to believe that marijuana use is even more likely to occur in the home than cigarette smoking given their differences in legal status.