Indoor Air Quality and Ventilation in Tuberculosis-Affected Households: A Cross-Sectional Assessment Using Carbon Monoxide and Carbon Dioxide

Abstract

Background: Poor ventilation can increase accumulation of re-breathed air and airborne Mycobacterium tuberculosis, while carbon monoxide (CO) reflects combustion-related indoor air pollution. Evidence integrating CO and carbon dioxide (CO₂) at the household level remains limited in TB-affected homes.
Objectives: To assess indoor air quality and ventilation status in TB-affected households using CO and CO₂ measurements, describe housing and ventilation characteristics, and examine associations with household and individual factors.
Methods: A community-based cross-sectional study included 180 households of pulmonary TB patients in urban and rural areas of Puducherry; a structured questionnaire recorded sociodemographic, housing, and household air-quality characteristics. We measured indoor CO and CO₂ using a real-time sensor. We used independent-samples t tests or one-way ANOVA for comparisons, and Pearson correlation for continuous variables.
Results: Mean indoor CO was 1.080 ± 0.155 ppm and mean CO₂ was 588.8 ± 176.6 ppm. No household exceeded the WHO CO values. CO₂ was ≤1000 ppm in 93.9% of households. Adequate overall ventilation was reported in 92.8% of households; however, cross-ventilation was present in only 16.7%. Among categorical variables, five were nominally associated with CO and none with CO₂. Income correlated with CO (r=0.154, p=0.039) and CO₂ (r=0.226, p=0.002), while number of rooms correlated with CO₂ (r=0.166, p=0.028).
Conclusion: Most TB-affected households had low CO and CO₂ concentrations, with few CO associations noted. Promoting universal ventilation, directly assessing CO₂, reducing biomass use, and ensuring appropriate fresh-air exchange during air-conditioner use remain relevant household TB-control measures.