The Nasal Microbiome and Associations With Environmental Exposures and Respiratory Health

Background: The nasal microbiome is directly in contact with the external environment and may play a role in respiratory health. This study aimed to evaluate the association of the nasal microbiome with air pollutants, meteorological conditions, and respiratory health in adolescents. Methods: We analyzed the nasal microbiome in 416 adolescents from the Project Viva cohort (mean age 13 years and 52% female). We tested for the association of alpha diversity, nasotypes, and bacterial genera abundance with environmental exposures from the past 2 days to the past year (PM_2.5, NO₂, O₃, temperature, humidity, residential greenness) and respiratory outcomes (asthma, hay fever, wheezing, IgE, aeroallergen sensitization, FeNO, lung function) through regression models adjusted for confounders and corrected using a false discovery rate (FDR) < 5%. Results: Bacterial diversity was positively associated with hay fever and short-term exposure to NO₂, while it was negatively correlated with temperature (FDR < 0.05). Adolescents whose nasal microbiome was dominated by Moraxella were exposed in the past week to lower O₃ levels (ORs: 0.73–0.76) and higher temperature and humidity (ORs: 1.19–1.26). Staphylococcus dominance was positively associated with aeroallergen sensitization compared to Propionibacterium dominance (OR: 4.48, FDR = 0.03). Thirteen and eight bacterial genera abundance were associated with short-to-medium-term exposures (PM_2.5, NO₂, temperature) and respiratory outcomes (hay fever, wheezing, IgE, FeNO, lung function) (FDR < 0.05). Staphylococcus, Corynebacterium, Pelomonas, Lactococcus, Lachnospiraceae (unclassified), and Faecalibacterium abundance were associated with both environmental exposures and respiratory traits. Conclusions: Nasal microbiome diversity was associated with hay fever, NO₂, and temperature exposure. Multiple short-to-medium-term environmental exposures and respiratory outcomes were associated with nasotypes and bacterial genera abundance in adolescents.