Yu-Yu Hsiao,1 Yi-Hsing Chen,2,3,4 Wei-Ting Hung,2 Kuo-Tung Tang2,3,5

1 Department of Internal Medicine, Taichung Veterans General Hospital, Taichung, Taiwan
2 Division of Allergy, Immunology, and Rheumatology, Taichung Veterans General Hospital, Taichung, Taiwan
3 Faculty of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan
4 College of Medicine, National Chung Hsing University, Taichung, Taiwan
5 Ph.D. Program in Translational Medicine and Rong Hsing Research Center for Translational Medicine, National Chung Hsing University, Taichung, Taiwan

Abstract

Background: Atopic dermatitis (AD) poses a significant disease burden in adults. Environmental factors are essential in its pathogenesis.
Objective: Given the possible role of air pollutants in allergic diseases, it is worthwhile to summarize the effects of outdoor air pollution on adult AD.
Methods: We undertook a systematic review based on PubMed and EMBASE as of August 16, 2021, and found 20 relevant studies. A random-effects meta-analysis was carried out.
Results: Regarding long-term effects (within months to years), traffic-related air pollution and particulate matter < 2.5 μm in diameter (PM2.5, per 10 μg/m3 increment) are associated with the prevalence of adult AD (OR 1.40, 95%CI [1.24, 1.58] and 1.67, 95%CI [1.26, 2.21]). Exposures to PM2.5 and nitrogen dioxide are associated with incident AD, with ORs of 2.30 (95%CI: 1.25, 4.25) and 1.30 (95%CI: 1.04, 1.61) per 10 μg/m3 increment. In terms of short term effects (within days), exposure to particulate matter < 10 μm in diameter (PM10) and sulfur dioxide (SO2) are associated with exacerbations of AD at lag day 0 based on those time-series studies, with an excessive risk of 2.9%, in particular, per 10 μg/m3 increment in SO2 exposure. In addition, both short-term and long-term exposures to these air pollutants are associated with AD symptoms (eczema, pruritus, and sleep disturbance).
Conclusions: Outdoor air pollutants exert both short-term and long-term adverse effects on adult AD, contributing to its development, severity and exacerbation of symptoms. The influence of air pollution should be considered in the management of adult AD.
Key words: Air Pollution, Atopic Dermatitis, Nitrogen Dioxide, Particulate Matter, Sulfur Dioxide