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

## TL;DR

This study finds that exposure to secondhand smoke and biomass cooking fuels increases the risk of developing pulmonary tuberculosis in southern Haryana, India.

## Contribution

The study identifies SHS and biomass fuel use as significant, independent risk factors for TB in a resource-limited setting.

## Key findings

- SHS exposure was associated with a 2.83 times higher risk of pulmonary TB.
- Biomass fuel use increased TB risk by 1.85 times compared to controls.
- Overcrowding and poor ventilation were also strongly linked to TB occurrence.

## Abstract

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.