Air pollution and tuberculosis

A large-scale ecological time-series study was conducted to assess the impact of outdoor air pollution on the risk of pulmonary tuberculosis (PTB) in China. The study spanned from January 2014 to December 2019 and analyzed 172,160 PTB cases across 67 sites located in five provinces, representing various geographic regions of the country. This comprehensive dataset allowed researchers to investigate pollutant-specific and time-lagged effects on PTB incidence.

The results showed significant associations between several air pollutants and the risk of PTB. Sulfur dioxide (SO₂) had the most immediate effect, with a 1.97% increase in PTB risk per 10 μg/m³ at a lag of zero weeks. Nitrogen dioxide (NO₂) was associated with a 1.30% increase in risk per 10 μg/m³, also strongest at lag zero. Particulate matter had more delayed effects: PM₁₀ increased PTB risk by 0.55% per 10 μg/m³ at a lag of eight weeks, and PM₂.₅ by 0.59% per 10 μg/m³ at a lag of ten weeks. Carbon monoxide (CO) showed the largest effect, with a 5.80% increase in PTB risk per 1 mg/m³, peaking at a lag of fifteen weeks.

Subgroup analyses indicated that the pollution effects were generally consistent across sexes and age groups. However, the risk was notably higher during colder seasons, particularly in winter and autumn, suggesting a role of seasonal environmental factors in amplifying pollution-related PTB risk. Although there were no significant differences by demographic subgroup, the seasonal variations were statistically significant.

Sensitivity analyses confirmed the robustness of these associations even after controlling for other co-pollutants. Notably, the effect of carbon monoxide displayed a non-linear dose-response pattern, with risk increasing up to a concentration threshold of 2.3 mg/m³ before tapering off.

In conclusion, outdoor air pollution was found to be significantly associated with elevated PTB risk in China, with distinct lag patterns and seasonal effects across different pollutants. These findings emphasize the importance of air quality control as a potential public health strategy to reduce the burden of tuberculosis.

Source: Li, Z., Liu, Q., Chen, L., Zhou, L., Qi, W., Wang, C., Zhang, Y., Tao, B., Zhu, L., Martinez, L. and Lu, W., 2024. Ambient air pollution contributed to pulmonary tuberculosis in China. Emerging Microbes & Infections, 13(1), p.2399275.