Early-life air pollution exposure: epigenetics and child allergy.

Globally, the incidence of allergic diseases in children has shown a significant upward trend, closely linked to environmental exposure in early life through epigenetic regulation mechanisms. Epigenetics enables dynamic regulation of genetic information via DNA methylation, histone modification, and non coding RNA without altering DNA sequence. The critical window from pregnancy to the first 1000 days of life is extremely sensitive to environmental factors exerting epigenetic effects, potentially influencing lifelong allergy susceptibility through fetal programming. This narrative review synthesizes current evidence on how early life air pollution exposure contributes to childhood allergic diseases via epigenetic mechanisms. A literature search was conducted using PubMed, Web of Science, Scopus, and Embase databases (up to December 2025). Studies were selected that provided mechanistic insights, epidemiological evidence from birth cohorts, or experimental findings relevant to epigenetic regulation. This review aims to provide a comprehensive overview of common air pollutant sources, their epigenetic effects at different developmental stages, and potential interventions during key windows to inform prevention and treatment strategies for childhood allergic diseases.