Air pollution and global healthcare use for atopic dermatitis: A systematic review

Increasing air pollution is common around the world, but the impacts of outdoor air pollution exposure on atopic dermatitis (AD) are unclear. We synthesized the current global epidemiologic evidence for air pollution exposure and associated medical visits for AD among adults and children. This review followed PRISMA guidelines, and searches were conducted on PubMed, MEDLINE, Web of Science and EMBASE databases. The searches yielded 390 studies, and after screening, 18 studies around the world assessing at least 5,197,643 medical visits for AD in total were included for the final analysis. We found that exposure to particulate matter ≤2.5 μm in diameter (PM_2.5 ) [(10/11) of studies], particulate matter ≤10 μm in diameter (PM₁₀ ) (11/13), nitrogen dioxide (NO₂ ) (12/14) and sulfur dioxide (SO₂ ) (10/13) was positively associated with AD visits. Results were equivocal for ozone [(4/8) of studies reported positive association] and limited for carbon monoxide [(1/4) of studies reported positive association]. When stratifying results by patient age, patient sex and season, we found that the associations with particulate matter, NO₂ and O₃ may be affected by temperature. Exposure to selected air pollutants is associated with AD visits, and increasingly poor worldwide air quality may increase global healthcare use for AD.