Effect of air pollution and greenness on the nasal microbiota in infancy

Abstract

Air pollution and greenness are associated with respiratory health in children but underlying mechanisms are not fully understood. We aimed to examine associations between fine particulate matter (PM_2.5), nitrogen dioxide (NO₂) and greenness (Normalized Difference Vegetation Index (NDVI)) with the early nasal microbiota, known to be relevant for respiratory health.

Microbiota characterization was performed using 16S rRNA pyrosequencing of 846 nasal swabs collected biweekly from 47 healthy infants. We investigated the association of PM_2.5, NO₂ and NDVI with the nasal microbiota. Exposures were individually estimated with spatial-temporal models incorporating satellite data. Generalized additive mixed models were used for analysis.

Increased PM_2.5 and NO₂ were associated with reduced within-subject Ružička dissimilarity (PM_2.5: per 1 µg/m³ -0.004, 95%CI -0.008, -0.001; NO₂: per 1 µg/m³ -0.004, 95%CI -0.007, -0.001). Whole microbial community comparison revealed distinct profiles in the groups exposed to high (p = 0.032) and medium (p = 0.001) PM_2.5 levels. Increased PM_2.5 was associated with reduced abundance of Corynebacteriaceae (∆% per 1 µg/m³ -4.9, 95%CI -8.4, -1.3) and Staphylococcaceae (∆% per 1 µg/m^₃: -4.3, 95%CI: -7.8, -6.7). Increased NO₂ was associated with reduced abundance of Corynebacteriaceae (∆% per 1 µg/m³ -6.8, 95%CI -9.8, -3.6). Increased NDVI was associated with reduced abundance of S. aureus (∆% per 0.1 NDVI -24.0, 95%CI -39.7, -4.3).

We found associations between air pollution and greenness with the nasal microbiota in healthy infants. This suggests that shaping of the early microbiota and its consecutive role in respiratory health may partly be driven through air pollution and greenness.