Causal relationships between air pollutants and upper respiratory tract infections: A two-sample, Mendelian randomization study.

Background: The issue of air pollution is a concern that affects the health of individuals globally. Air pollutants (APs) have been linked to upper respiratory tract infections (URTIs); however, the exact association between them remains unclear.

Methods: Two-sample Mendelian randomization (MR) was performed to examine the causal relationship between APs and URTIs. Data regarding APs and URTIs were obtained from genome-wide association studies. Single nucleotide polymorphisms associated with each exposure were defined as instrumental variables. Inverse variance weighting is the primary method for analyzing causal effects. Quality control was performed using MR-Egger, weighted mode, simple mode, and weighted median. Heterogeneity was assessed using Cochran's Q. The MR-Egger test was used to evaluate pleiotropy. Sensitivity analysis was performed using the "leave-one-out" method.

Results: MR analysis revealed that airborne particulate matter with a diameter ≤ 10 micrometers (PM10) had a notable impact on acute pharyngitis, whereas nitrogen dioxide had a significant impact on chronic rhinitis, chronic nasopharyngitis, and chronic pharyngitis. Pleiotropy and heterogeneity were not observed.

Conclusion: Higher PM10 levels were associated with a greater likelihood of developing acute pharyngitis. Increased nitrogen dioxide concentrations were associated with an increased risk for chronic rhinitis, nasopharyngitis, and pharyngitis. As such, controlling APs is crucial for preventing and treating URTIs.