Background: Little is known about the effects of secondhand marijuana smoke on children. We aimed to determine caregiver marijuana use prevalence and evaluate any association between secondhand marijuana smoke, childhood emergency department (ED) or urgent care (UC) visitation, and several tobacco-related illnesses: otitis media, viral respiratory infections (VRIs), and asthma exacerbations.

Methods: This study was a cross-sectional, convenience sample survey of 1500 subjects presenting to a pediatric ED. The inclusion criteria were as follows: caregivers aged 21–85 years, English- or Spanish-speaking. The exclusion criteria were as follows: children who were critically ill, medically complex, over 11 years old, or using medical marijuana.

Results: Of 1500 caregivers, 158 (10.5%) reported smoking marijuana and 294 (19.6%) reported smoking tobacco. Using negative-binomial regression, we estimated rates of reported ED/UC visits and specific illnesses among children with marijuana exposure and those with tobacco exposure, compared to unexposed children. Caregivers who used marijuana reported an increased rate of VRIs in their children (1.31 episodes/year) compared to caregivers with no marijuana use (1.04 episodes/year) (p = 0.02).

Conclusions: Our cohort did not report any difference with ED/UC visits, otitis media episodes, or asthma exacerbations, regardless of smoke exposure. However, caregivers of children with secondhand marijuana smoke exposure reported increased VRIs compared to children with no smoke exposure.