Exposure to Environmental Pollutants and the Risk of Respiratory Illnesses in 36-Month-Old Children: The Korean Children's Environmental Health Study (Ko-CHENS).

Abstract

Purpose: This study aimed to investigate the association of exposure to environmental pollutants and surrounding residential environments with the development of respiratory illnesses in 36-month-old children using data from the Korean CHildren's ENvironmental health Study.

Methods: Demographic information and anthropometric measurements were obtained from the newborns. At 36 months of age, indoor environmental pollutant levels (particulate matter [PM₁₀ and PM_2.5], volatile organic compounds, and house dust mite allergens) were measured during home visits. Concentrations of both heavy metals (lead, mercury, and cadmium) in blood and metabolites of environmental hormones in urine were analyzed. A structured questionnaire was used to assess the presence of 6 common respiratory illnesses (infantile asthma, current asthma, recurrent wheezing, allergic rhinitis, bronchiolitis, and pneumonia) and residential environmental characteristics. Quantile-based g-computation was employed to estimate the joint association of exposure to mixtures of physical and chemical environmental factors with the risk of respiratory illnesses.

Results: Among the total of 4,059 children, current allergic rhinitis was the most prevalent respiratory illness at 36 months. Compared with children without respiratory illnesses, those with respiratory illnesses showed significantly higher frequencies of exposure to environmental tobacco smoking and pet ownership. Dust mite concentrations were higher among children with recurrent wheezing and pneumonia. Mixture exposure analysis revealed that overall mixture exposure was positively associated with current allergic rhinitis, largely driven by lead and phthalate metabolites, and with pneumonia, mainly attributable to phthalate metabolites. Exposure to a mixture of multiple chemicals was positively associated with infantile asthma and current asthma.

Conclusions: Direct and indirect exposures to environmental pollutants are closely associated with the development of respiratory illnesses in young children, and the surrounding residential environment during early childhood also plays a critical role in determining respiratory disease risk. These findings support the need for systematic and sustainable environmental management at both individual and community levels to protect children who are particularly vulnerable to environmental hazards.