Ambient air pollutants are associated with newly diagnosed tuberculosis: A time-series study in Chengdu, China

Although a few studies have analyzed the associations between ambient air pollutants and the development of tuberculosis (TB), most have been conducted in the core countries with inconsistent results. In this study, we used a distributed lag non-linear model to investigate the associations between the newly diagnosed TB cases and daily exposure to particulate matter with an aerodynamic diameter of <10μm (PM₁₀), nitrogen dioxide (NO₂), and sulfur dioxide (SO₂) in Chengdu, a severely polluted city. There were 36,108 newly diagnosed active TB cases from January 1, 2010 to December 31, 2015 in Chengdu. In a single-pollutant model, the cumulative relative risk of active TB cases was 1.06 [lag of 0 to 21days, 95% confidence interval (CI): 1.01-1.11] for each 10μg/m³ increase in PM₁₀ above the threshold of 70μg/m³; 1.06 (lag of 0 to 2days, 95% CI: 1.03-1.09) for each 10μg/m³ increase in NO₂ above the threshold of 40μg/m³; and 1.07 (lag of 0 to 2days, 95% CI: 1.02-1.12) for each 10μg/m³ increase in SO₂ above the threshold of 60μg/m³. Meanwhile, we found a positive association in males after exposure to a 10μg/m³ increase in SO₂ above the threshold of 60μg/m³ at a lag of 0 to 2days. Exposure to PM₁₀, NO₂, and SO₂ was associated with an increment in the incidence of active TB cases.