Association of exposure to environmental tobacco smoke at home and risk of mortality among US never smokers by race/ethnicity, education, and income

Environmental tobacco smoke (ETS) increases the risk of mortality among nonsmokers. Yet, few studies have examined this association among racial/ethnic minorities or among people with less education or income. We assessed self-reported ETS exposure at home among never smoking participants (n = 110,945) of the 1991-2010 National Health Interview Surveys. Deaths through 2015 were identified by the National Death Index. Hazard ratios (HRs) and 95% confidence intervals (CIs) for all-cause and cause-specific mortality were estimated using Cox proportional hazards regression models with age as the underlying time metric and adjusted for sex, race/ ethnicity, education, household income, body mass index, region of residence, and survey year. We further stratified all-cause mortality analyses by race/ethnicity, household income, and education. Relative to no ETS at home, every day exposure was associated with higher risk of all-cause mortality (HR = 1.33, 95%CI: 1.23, 1.45), with similar HRs observed across strata of education and income. HRs were similar among non-Hispanic Black (HR = 1.28, 95%CI: 1.08, 1.53) and non-Hispanic White adults (HR = 1.34, 95%CI: 1.21, 1.48) although somewhat higher among Hispanic adults (HR = 1.65, 95%CI: 1.29, 2.10; P for pairwise comparison = 0.04). ETS exposure at home is an important contributor to mortality across strata of race/ethnicity, education, and income in the US.