How Air Pollution Fuels Respiratory Infections in Children: Current Insights

Susanna Maria Roberta Esposito ^1* Valentina Fainardi ¹ Annachiara Titolo ¹ Angela Lazzara ¹ Marialaura Menzella ¹ Beatrice Campana ¹ Alberto Argentiero ¹ Nicola Principi ²

• ¹ Clinica Pediatrica, Ospedale Universitario di Parma, Parma, Italy
• ² University of Milan, Milan, Lombardy, Italy

Air pollution is a significant global health concern, particularly for children, who are highly susceptible to its adverse effects. Pollutants such as particulate matter (PM), nitrogen oxides (NO and NO₂), sulfur dioxide (SO₂), ozone (O₃), and carbon monoxide (CO) increase the risk of upper (URTI) and lower respiratory tract infections (LRTI). While this link is well-documented, gaps remain in understanding specific pollutant roles, risk magnitude, and influencing factors like age, sex, and exposure duration. To assess this relationship and highlight research priorities, a literature review was conducted using the MEDLINE/PubMed database for studies published from 2000 to 2024. Eligible studies included randomized controlled trials, cohort studies, and meta-analyses. Studies were categorized by pollutant type, exposure timing, and infection type. Findings confirm that air pollution significantly raises the risk of URTI and LRTI, with infants and young children being most vulnerable. Identified mechanisms include oxidative stress, inflammation, immune dysregulation, and genetic changes. Prenatal exposure alters lung development, increasing LRTI and acute otitis media (AOM) risk, while both short- and long-term postnatal exposures lead to severe and recurrent LRTIs, reduced quality of life, frequent hospitalizations, and higher mortality. However, data limitations prevent precise quantification of risk, pollutant-specific effects, and the influence of exposure characteristics. Inconsistent findings regarding pollutant combinations and diseases like AOM highlight the need for further research. Air pollution is a critical factor in pediatric respiratory infections. However, current knowledge is insufficient to guide effective prevention and treatment strategies. Further research is essential to explore pollutant interactions, circulation patterns, and environmental influences such as climate change. These findings must be translated into public health policies and clinical interventions to safeguard children's respiratory health.