Secondhand smoke exposure and asthma status among adolescents: Findings from the 2019-2020 California Student Tobacco Survey

Background and objectives: Secondhand tobacco smoke is associated with worsening asthma symptoms among children. However, the relationship between secondhand marijuana smoke and asthma symptoms among youth has not been examined. This study compares the prevalence of secondhand tobacco and marijuana smoke exposure, overall and by asthma status, among middle and high school students. Methods: The study assessed participants of the 2019-2020 California Student Tobacco Survey: a large, crosssectional random sample of 8th, 10th, and 12th graders (N = 158,937). Descriptive analyses examined exposure to combustible tobacco and marijuana secondhand smoke by students' asthma status and sociodemographic characteristics. Results: More students with asthma were exposed to combustible tobacco secondhand smoke (13.4 %) and marijuana secondhand smoke (12.0 %) than students without asthma (10.9 % and 9.3 %, respectively). The prevalence of secondhand marijuana smoke exposure was higher among 12th grade students (12.2 %) while the prevalence of secondhand tobacco smoke exposure was higher among 8th grade students (13.4 %) and those who lived in rural locations (15.4 %). Conclusions: California students are exposed to marijuana secondhand smoke at similar proportions to combustible tobacco secondhand smoke and more students with asthma are exposed to marijuana secondhand smoke. These results expand the public health issue of secondhand smoke exposure among children with asthma by highlighting the need to examine marijuana secondhand smoke. Given the rapid shift in marijuana laws across the US, exposure to secondhand marijuana smoke is likely to increase. Therefore, vulnerable populations, such as children with asthma, should be prioritized for interventions that aim to alleviate secondhand marijuana exposure.