Secondhand Smoke and Biomass Fuel Exposure as Risk Factors for Pulmonary Tuberculosis: A Matched Case-Control Study From Southern Haryana.

Introduction Secondhand smoke (SHS) exposure and biomass cooking fuel utilization represent persistent and growing health threats in regions where tuberculosis (TB) poses major public health risks. This comprehensive study conducted in Nuh district, Haryana, India, investigated the association between environmental exposures, including SHS and biomass cooking fuel use, with pulmonary TB development. Methodology This matched case-control study included 218 newly diagnosed pulmonary TB cases matched with 218 non-TB controls recruited from the same healthcare facility. Cases comprised nonsmoking adult men and women presenting as incident pulmonary TB patients diagnosed at the Tuberculosis Detection Center (TDC) through standard guidelines. Data were collected as a structured questionnaire. Bivariate logistic regression assessed associations between dependent and independent variables. Adjusted odds ratios were calculated for significant associations. Results Kitchen facilities analysis showed 192/436 (44%) homes without separate cooking areas and 215/436 (49.3%) lacking exhaust ventilation. Cooking fuel analysis revealed 73/218 (33.5%) cases used biomass fuels compared to 42/218 (19.3%) controls. Results demonstrated significant associations between TB and environmental risk factors: SHS exposure (adjusted odds ratio (OR) 2.83, 95% confidence interval (CI): 1.39-5.75), biomass fuel use (adjusted OR 1.85, 95% CI: 1.13-3.03), overcrowding (adjusted OR 2.85, 95% CI: 1.69-4.78), and inadequate ventilation (adjusted OR 1.65, 95% CI: 1.08-2.52). Conclusions The findings provide compelling evidence for the role of indoor air pollution and environmental tobacco smoke exposure in TB pathogenesis among vulnerable populations in resource-limited settings. SHS exposure and biomass cooking fuel use emerged as independent risk factors with substantial effect sizes, supporting biological mechanisms linking indoor air pollution to TB susceptibility. Additional environmental factors, including overcrowding, dampness, and inadequate ventilation, demonstrated strong associations with disease occurrence.