Ambient air pollution contributed to pulmonary tuberculosis in China

Abstract

Published studies on outdoor air pollution and tuberculosis risk have shown heterogeneous results. Discrepancies in prior studies may be partially explained by the limited geographic scope, diverse exposure times, and heterogeneous statistical methods. Thus, we conducted a multi-province, multi-city time-series study to comprehensively investigate this issue. We selected 67 districts or counties from all geographic regions of China as study sites. We extracted data on newly diagnosed pulmonary tuberculosis (PTB) cases, outdoor air pollutant concentrations, and meteorological factors in 67 sites from January 1, 2014 to December 31, 2019. We utilized a generalized additive model to evaluate the relationship between ambient air pollutants and PTB risk. Between 2014 and 2019, there were 172,160 newly diagnosed PTB cases reported in 67 sites. With every 10-μg/m³ increase in SO₂, NO₂, PM₁₀, PM_2.5, and 1-mg/m³ in CO, the PTB risk increased by 1.97% [lag 0 week, 95% confidence interval (CI): 1.26, 2.68], 1.30% (lag 0 week, 95% CI: 0.43, 2.19), 0.55% (lag 8 weeks, 95% CI: 0.24, 0.85), 0.59% (lag 10 weeks, 95% CI: 0.16, 1.03), and 5.80% (lag 15 weeks, 95% CI: 2.96, 8.72), respectively. Our results indicated that ambient air pollutants were positively correlated with PTB risk, suggesting that decreasing outdoor air pollutant concentrations may help to reduce the burden of tuberculosis in countries with a high burden of tuberculosis and air pollution.

Keywords: Outdoor air pollutants; pulmonary tuberculosis; risk; time-series.

Figure 1.

Percentage changes in pulmonary tuberculosis risk and their 95% confidence intervals for each 10-μg/m³ (1-mg/m³ for CO) increase in ambient air pollutant concentrations at all lag weeks. Abbreviation: PTB = pulmonary tuberculosis. The results were adjusted for the week, the number of cases in the previous week, the number of holidays in the week, season, city, average temperature, average wind speed, and average relative humidity at the same lag week.

Figure 2.

The concentration-response curves between ambient air pollutants and pulmonary tuberculosis risk. The x-axis represents the concentration of air pollutants, while the y-axis represents the contribution of the smooth term to the fitted values. We applied lag 0 week for SO₂, lag 0 week for NO₂, lag 8 weeks for PM₁₀, lag 10 weeks for PM_2.5, and lag 15 weeks for CO. The results were adjusted for the week, the number of cases in the previous week, the number of holidays in the week, season, city, average temperature, average wind speed, and average relative humidity at the same lag week.