Ambient Air Pollution Exposures and Newly Diagnosed Pulmonary Tuberculosis in Jinan, China: A Time Series Study

Few epidemiological studies have evaluated the effects of air pollution on the risk of pulmonary tuberculosis (TB). We investigated the associations of ambient air pollutants (particulate matter with aerodynamic diameter <2.5 μm (PM_2.5), sulfur dioxide (SO₂),nitrogen dioxide (NO₂), ozone (O₃), and carbon monoxide (CO)) in relation to the risk of pulmonary TB in a cohort of Chinese TB patient in Jinan city from 2011 to 2015. A total of 9344 newly diagnosed pulmonary TB cases were included. Poisson regression model was employed to estimate the risk of air pollution and daily diagnosed pulmonary TB. Four different air pollution exposure windows (3, 6, 9, and 12 months) before TB diagnoses were calculated from the daily concentration of air pollution. In overall analysis, we did not find strong evidence for an association between continuous exposures to most ambient air pollutants and risk for pulmonary TB. However, in categorical analysis, we observed statistically significant overall associations between pulmonary TB risk and PM_2.5 (3 month exposure window: RR = 1.228, 95%CI: 1.091-1.381) as well as CO (3 month exposure window: RR = 1.169, 95%CI: 1.028-1.329; 9 month exposure window: RR = 1.442, 95%CI: 1.028-2.024) exposures. Moreover, subgroup analyses suggested that most of the air pollutants (PM_2.5, SO₂, O₃, and CO) were significantly associated with increased risk of TB among the males, the females, the <60 years, and the smear negative cases. The dominant statistically significant associations were detected at 3-month exposure window of air pollution before the diagnosis of TB. Our results detected positive associations between ambient PM_2.5, CO exposures and the risk of newly diagnosed pulmonary TB in China. The suggestive evidence that the 3 month air pollution exposure window was associated with increased TB risk warrants further investigation.