The impact of air pollution on active tuberculosis development from latent tuberculosis infection in rural China: 10-year follow-up of a cohort study

Background The aim of the study was to investigate the impact of major air pollutants on the development of tuberculosis (TB) among adults with latent tuberculosis infection (LTBI) in rural areas in China. Methods Based on a population-based multicentre cohort study conducted since 2013, we aimed to examine the associations between various air pollutants and the risk of active TB development from LTBI. The estimates were assessed using time-dependent Cox regression models, with nonlinearity evaluated by restricted cubic splines. The China High Air Pollutants datasets were used to feature high-resolution, high-quality, near-surface air pollution data in China. Results A total of 20 869 participants were followed for 10 years, and 185 incident TB cases were identified. Long-term exposure to PM 2.5 , PM 10 , SO 2 , NO 2 and CO was found to be significantly correlated with increased risk of TB from LTBI development with an adjusted hazard ratio (aHR) between 1.03 (95% CI: 1.01–1.06) and 1.48 (95% CI: 1.38–1.58), while O 3 exposure was linked to reduced risk with an aHR of 0.86 (95% CI: 0.83–0.89). Subgroup analysis according to baseline LTBI status suggests that air pollution has an impact on active TB risk for both short-term and long-term infections. Additionally, pollutants generally show positive correlations with each other, except for O 3 , which was negatively correlated with SO 2 and CO. With respect to TB risk, the dose–response relationships showed linearity for PM 2.5 but significant nonlinearity for PM 10 , SO 2 , NO 2 , CO and O 3 . Discussion Long-term exposure to air pollutants increased the risk of active TB development from LTBI, highlighting the importance of air pollution control in LTBI management allowing for regional and demographic differences.