Air pollution exposure and the burden of pediatric upper respiratory tract infections in emergency departments: a retrospective time-series study

Upper respiratory tract infections (URTI) are a major public health problem and a leading cause of pediatric Emergency Department (ED) visits. Approximately 81% of emergency outpatient visits in children are due to URTI, and respiratory diseases account for 12% of all deaths worldwide. Air pollution is considered an important factor contributing to the increased incidence of respiratory infections. The aim of this study was to examine the association between ambient air pollutant concentrations and the number of pediatric ED admissions for URTI. We conducted a retrospective analysis including 2,572 children admitted to the ED between 2015 and 2020 with a diagnosis of URTI. Daily concentrations of particulate matter (PM₂.₅ and PM₁₀), carbon monoxide (CO), nitrogen oxides (NO_x and NO₂), ozone (O₃), and sulfur dioxide (SO₂) were obtained from a certified environmental monitoring station. Negative binomial regression models were used to estimate associations, adjusting for season, temperature, humidity, and influenza activity. The highest number of URTI-related visits was observed in winter 2019, coinciding with the peak levels of air pollutants. In univariate analyses, higher concentrations of PM₂.₅, PM₁₀, CO, and SO₂ were significantly associated with increased URTI visits. After multivariable adjustment, only carbon monoxide (IRR = 1.72, p = 0.05) and sulfur dioxide remained independently associated with higher URTI incidence, while the associations for particulate matter and nitrogen dioxide were attenuated. Ozone showed a weak inverse association, likely reflecting seasonal confounding. Conclusion: Our findings indicate that air pollution is strongly associated with the frequency of pediatric URTI-related ED visits. While seasonality plays an important role, CO and SO₂ appear to be key independent factors driving this association. These findings suggest that exposure to ambient CO and SO₂ may increase the risk of pediatric upper respiratory infections, highlighting the importance of air quality in the prevention of respiratory morbidity in children. What is Known: • Upper respiratory tract infections (URTI) are a major public health issue • Environmental exposure, particularly to ambient air pollutants, pose significant health risks What is New: • Exposure to ambient carbon monoxide (CO) and sulfur dioxide (SO₂) may increase the risk of pediatric upper respiratory tract infections • The data suggest that improving air quality may help mitigate respiratory morbidity among children.