Association of pollution and climate with atopic eczema in US children

Background: We sought to determine the relationship between childhood eczema, climate, and environmental pollutants. Methods: We analyzed data from the 2007–2008 National Survey of Children's Health including a representative sample of 91,642 children age 0–17 years and the 2006–2007 Environmental Protection Agency measurements of carbon monoxide (CO), nitrate (NO₃), nitrogen dioxide (NO₂), organic carbon (OC), sulfate (SO₃), sulfur dioxide (SO₂), particulate matter ≤2.5 μm (PM-2.5) and <10 μm (PM-10), and tropospheric ozone levels, and the National Climate Data Center measurements of relative humidity (%), issued UV index, outdoor air temperature, and precipitation levels. Results: In multivariate survey logistic regression models controlling for age, sex, race/ethnicity, household income, US birthplace, and history of moving to a new location, eczema was associated with higher mean annual NO₂ (p = 0.008), SO₂ (p = 0.006), SO₃ (p = 0.0002), arsenic (p = 0.0007), nickel (p = 0.0002), lead (p = 0.03), vanadium (p < 0.0001), and zinc (p = 0.003), but lower NO₃ (p = 0.002), OC (p = 0.03), PM-2.5 (p = 0.006), cadmium (p < 0.0001), copper (p = 0.004), and potassium (p < 0.0001). In contrast, moderate–severe eczema was associated with higher NO₃ (p = 0.03), OC (p = 0.008) and PM-2.5 (p = 0.01), copper (p = 0.04), lead (p = 0.008), and zinc (p = 0.01), but lower CO (p = 0.03). Principal component analysis was used and identified 4 combinations of pollutants and climate factors occurring in the USA, of which 1 was associated with higher prevalence and two were associated with lower prevalences of eczema (p < 0.05). Conclusions: Pollutants in conjunction with climate factors may differentially impact eczema prevalence and severity, some with apparent harmful effects.