Associations of fine particulate matter and its constituents with airway inflammation, lung function, and buccal mucosa microbiota in children

Background Previous studies have suggested acute effects of ambient fine particulate matter (PM2.5) air pollution on respiratory health among children, but evidence for PM2.5 constituents and respiratory health were still limited. Objectives To investigate associations of short-term exposure to PM2.5 and its constituents with airway inflammation, lung function, and airway microbiota in children. Methods We conducted a longitudinal panel study with 3 repeated health measurements among 62 children in Shanghai, China from November 2018 to June 2019. Respiratory health was measured by fractional exhaled nitric oxide (FeNO), saliva tumor necrosis factor-α (TNF-α), lung function (forced vital capacity and forced exhaled volume in 1 s), and microbiota diversity in buccal mucosa samples. Based on the linear mixed-effect models, we applied the single-constituent models and the constituent-PM2.5 adjustment models to examine the associations between PM2.5 constituents and health outcomes. Result Short-term exposure to PM2.5 was associated with higher TNF-α, FeNO levels and reduced lung function. Among all constituents, organic carbon, elemental carbon, NO3− and NH4+ had the consistent and strongest associations with airway inflammation biomarkers and lung function parameters, followed by metallic elements. We also found short-term PM2.5 exposure was associated with decreased diversity in buccal mucosa bacterial community and two bacterial phyla, Fusobacteria and Proteobacteria, were identified as differential microbes with PM2.5 exposure. Conclusion Short-term exposure to PM2.5 may impair children's respiratory health represented by higher airway inflammation, lower lung function and altered buccal mucosa microbial colonization. Organic carbon, elemental carbon, NO3− and NH4+ may dominate these effects.