Objective: Concentrations of air pollutants (PM in particular) in Poland are one of the highest in the EU. Although the influence of air pollutants (AP) exposure on increasing risk of viral infections is widely known, there is lack of comprehensive research on relationships between AP exposure and hospitalizations due to respiratory syncytial virus (RSV) infections.

Materials and methods: Data from the National Health Fund on RSV LRTIs from 10 consecutive seasons (2010-2019) and official data on daily mean concentrations of PM_2.5, PM₁₀ and NO₂ from 7 Polish cities were used. Patients were included in the analyses based on the final diagnosis of J12.1, J20.5 and J21.0.

General Regression Models (GRM) were used to determine the statistically significant effects of single variables with their interactions on health outcomes. Models were evaluated using the adjusted coefficient of determination (R²).

Results: 7 cities with the highest number of RSV cases (12,485 hospitalizations in total) were included in the analyses. A substantial part of the RSV hospitalizations in these cities and the analyzed period may have been attributable to the AP. R² in case of multivariate models varied from 0.05 in the city of Walbrzych to 0.31 in case of Gdansk.

10 ?g/m³ increase of PM_2.5, PM₁₀ and NO₂ concentration was associated with an average growth in RSV hospitalizations of 0.087-0.16, 0.031-0.087 and 0.04-0.29 respectively. In the univariate model, most significant effects were observed in PM_2.5 and NO₂. Significant association between concentration of these AP and RSV hospitalization was found in 5 out of 7 cities.

Conclusions: PM2.5, PM10 and NO2 concentrations explain noticeable part of pediatric RSV hospitalizations.