​Summary: Tobacco smoke has been associated with negative health outcomes, including those with chronic respiratory illnesses, such as asthma. This study aimed to assess the relationship between exposure to environmental tobacco smoke (ETS), as well as tobacco use (cigarette and electronic cigarettes), on asthma severity among adults with current asthma, with stratification by sex to understand potential biological sex differences.

The study population consisted of Californian adults 18 years or older with self-reported physician/health care diagnosis of asthma and still having current asthma from 2020 California Health Interview Survey. All descriptive statistics and analyses were sex-stratified and survey-weighted. Crosstabulations were used to eBunderstand the association between asthma attack and ETS or firsthand smoke exposure, while binary logistic regression models were used to assess the effect of ETS exposure, current smoking status, and control variables on asthma attack in the past 12 months, with a sub-analysis among nonsmoking adults with asthma.

Findings: Among the primary variable of interest, 35% of males and 30% of females reported ETS exposure in the past 12 months, while 13% of males and 6% of females reported being a current smoker. Past year asthma attack was reported among 43% and 55% of males and females, respectively. Among males, after adjusting for all control variables, asthma attack was significantly higher among those with ETS exposure and among current smokers. Male nonsmokers with ETS exposure had a 109% higher odds of asthma attack, compared to non-exposure individuals.

Using a population-based survey, results highlight the ongoing burden of tobacco use and exposure particularly among males with current asthma, further corroborate the literature on the relationship between tobacco and asthma, and highlight putative sex-specific outcomes.