Unravelling sociodemographic inequities in household secondhand smoke exposure among non-smokers in Malaysia: A secondary analysis of National Health and Morbidity Survey (NHMS) 2019.

INTRODUCTION: Secondhand smoke (SHS) exposure remains a significant global public health issue. Identifying the factors contributing to SHS exposure is crucial for developing targeted, evidence-based interventions to mitigate its impact. This study examines the patterns and determinants of SHS exposure at home among non-smoking Malaysians. METHODS: Data were derived from the National Health and Morbidity Survey (NHMS) 2019, which employed a cross-sectional design and multistage sampling to gather a representative sample of Malaysians aged ≥15 years. Demographic data and information on SHS exposure at home within the past month, were collected via a structured questionnaire. Weighted data were analyzed using chi-square tests and multivariable logistic regression. RESULTS: Of the 1876 participants (representing an estimated 3.54 million individuals), 19.8% (95% CI: 18.5-21.1) reported SHS exposure at home. Several sociodemographic factors were significantly associated with SHS exposure. Logistic regression analysis revealed higher odds of exposure among females (adjusted odds ratio, AOR=1.85; 95% CI: 1.55-2.29), Malays (AOR=2.65; 95% CI: 1.86-3.78), Bumiputera Sabah (AOR=4.16; 95% CI: 2.72-6.37), and Bumiputera Sarawak (AOR=3.67; 95% CI: 2.32-5.80). Other significant factors included being aged ≤24 years (AOR=1.87; 95% CI: 1.26-2.78) and belonging to a low income group (quintile 1; AOR=1.42; 95% CI: 1.12-1.95). Interaction analysis also identified significant two-way interactions between sex and some sociodemographic independent variables. CONCLUSIONS: Approximately two in ten non-smoking Malaysians were exposed to SHS at home. These findings underscore the need for comprehensive tobacco control measures that raise awareness about the health risks of SHS exposure at home. Educational campaigns should focus on promoting smoke-free home environments, particularly among the high-risk groups identified in this study.