Association of individual exposure to PM2.5 components with pulmonary tuberculosis hospitalization and the effect modification by greenness

It remains unknown of the effects of short-term exposure to components of ambient particulate matter with aerodynamic diameters < 2.5 μm (PM 2.5 ) on pulmonary tuberculosis (PTB) hospitalization and the effect modification by greenness at an individual level. We collected information on 4,524 PTB hospital admissions, PM 2.5 and its components (sulphate [SO 4 2− ], nitrate [NO 3 − ], ammonium [NH 4 + ], organic matter [OM], and black carbon [BC]) in Hainan, China during 2016–2019. Based on case-crossover design, we used conditional logistic regression models with stabilized inverse probability weights to explore the associations between PM 2.5 components and PTB hospitalization. We found that risk of PTB hospitalization increased by 9.77% (95% confidence interval [CI]: 2.60, 17.44%), 14.68% (7.25, 22.64%), 8.53% (1.84, 15.66%), 10.81% (3.84, 18.26%), 6.82% (0.78, 13.23%), and 10.07% (3.17, 17.44%) for every interquartile range increase in PM 2.5 , SO 4 2− , NO 3 − , NH 4 + , OM, and BC, respectively. SO 4 2− (41.6%) together with BC (39.0%) contributed > 80% of the total effects of the five components. PM 2.5 and its components posed higher risk for patients aged ≥ 65 years, those living in prefecture-level cities, and in the warm season. The adverse effects were statistically significant for the patients living in low-NDVI (normalized difference vegetation index < 0.45) regions, but not for those in other regions. This study provides evidence for the adverse impacts of PM 2.5 components on PTB hospitalization. Our study highlights the necessity for targeted intervention strategies to reduce the PTB burden and thereby improve public health outcomes. Specifically, reducing the emission of PM 2.5 , especially SO 4 2− and BC, and increasing green spaces in low-NDVI regions (e.g., developing new parks and gardens, encouraging rooftop greening on buildings, and restoring degraded forests) would be of great significance.