Long-term effect of exposure to ambient air pollution on the risk of active tuberculosis.

Objectives: To explore the long-term effect of exposure to ambient air pollution on the risk of active tuberculosis (TB).

Methods: We constructed a distributed-lag nonlinear model (DLNM) to evaluate the relatively long-term influence of outdoor PM, PM, SO and NO exposure on active TB risk in the city of Lianyungang in Jiangsu Province, China.

Results: There were 7,282 TB cases reported in the study area during 2014-2017, with annual median (interquartile range) concentrations of PM, PM, SO and NO at 45.86 (34.57-64.14) μg/m, 85.43 (62.86-116.14) μg/m, 22.00 (15.71-30.86) μg/m and 30.00 (23.29-38.57) μg/m, respectively. The single-pollutant model showed that for each 10 μg/m increase in concentration, the cumulative relative risk of TB was 1.12 (lag 0-24 weeks, 95% CI: 1.03-1.22) for PM with reference to 35 μg/m; 1.11 (lag 0-21 weeks, 95% CI: 1.06-1.17) for PM with reference to 70 μg/m; 1.37 (lag 0-20 weeks, 95% CI: 1.16-1.62) for SO with reference to 60 μg/m; and 1.29 (lag 0-22 weeks, 95% CI: 1.11-1.49) for NO with reference to 40 μg/m. In the multipollutant model considering both PM and NO, the association remained significant.

Conclusions: Our results revealed a potential association between outdoor exposure to PM, PM, SO, and NO and active TB. Considering that people from developing countries continue to be exposed to both severe outdoor air pollution and high rates of latent TB infection, the association between worsening air pollution and active TB deserves further attention.