Association between ambient particulate matter and latent tuberculosis infection among 198 275 students

Numerous studies have estimated the impact of outdoor particulate matter (PM) on tuberculosis risk. Nevertheless, whether there is an association between ambient PM and latent tuberculosis infection (LTBI) risk remains uncertain.

We collected the basic information and LTBI test results of students who underwent freshmen enrolment physical examinations in 68 middle schools from six prefecture-level cities located in eastern China between 2018 and 2021. We also extracted data on air pollutant concentrations and meteorological factors in six cities between 2015 and 2021. We applied the generalised additive model (GAM) to assess the effect of PM on LTBI risk.

We included 198 275 students in the final analysis, of whom 11 721 were diagnosed with LTBI. The LTBI group had higher proportions of males (P < 0.001), individuals of Han nationality (P < 0.001), and body mass index compared to the non-LTBI group (P < 0.001). For each 1-μg/m³ increase in PM₁₀ concentration, the LTBI risk increased by 0.82% (95% confidence interval (CI) = 0.65-1.00), 0.90% (95% CI = 0.73-1.08), and 0.86% (95% CI = 0.69-1.03) when lagged at one, two, and three years, respectively. For PM_2.5, the LTBI risk increased by 0.91% (95% CI = 0.63-1.20), 1.05% (95% CI = 0.75-1.36), and 1.32% (95% CI = 0.96-1.69) when lagged at one, two, and three years, respectively.

Outdoor PM concentration was positively correlated with LTBI risk. Considering that many developing countries are facing the dual challenges of high LTBI rates and serious ambient air pollution, reducing outdoor PM concentration would contribute to alleviating their tuberculosis burden.