Symptoms of atopic dermatitis are influenced by outdoor pollution
JACI, June 2013: Outdoor air pollution is related to exacerbation of pre-existing asthma and even with the development of atopic diseases or allergic sensitization. In contrast, there are few studies to show the association between outdoor air pollution and atopic dermatitis (AD).
In a Letter to the Editor published in The Journal of Allergy & Clinical Immunology (JACI), Kim et al theorized that symptoms of AD would be affected by outdoor air pollution. They enrolled 22 patients (17 boys and 5 girls) with AD living in Seoul, Korea, and followed them for 18 months between July, 2009, and December, 2010. Symptoms, frequency of bathing, application of moisturizers, and the use of topical corticosteroids (TCS) were recorded on a daily basis. The authors obtained daily mean concentrations of particulate matters (PMs), nitric oxides (NO, NO2, NOx), volatile organic compounds (VOCs) including benzene, toluene, ethyl-benzene, xylene, and styrene, and 24 hour average temperature and relative humidity from the closest monitoring sites to each patient’s residence during the study period to estimate the patients’ exposure to outdoor air pollution and meteorological conditions. These sites were operated by Seoul Metropolitan Government Research Institute of Public Health and Environment. A generalized linear mixed model (GLMM) was used to assess the association between outdoor air quality and AD symptoms. The researchers analyzed the level of air pollutants from the same day, the previous day (lag 1), and 2 days (lag 2) before the report of AD symptoms in separate models.
From symptom records of 1,880 person-days, the authors found that AD symptoms were associated with the levels of outdoor air pollutants such as PM, toluene, and TVOC. Interestingly, this association varied according to season, and the lag effect of PM10, benzene, and TVOC on AD symptoms was found after exposure. The authors’ findings suggest that outdoor air pollution acts as an aggravating factor in AD as it does in asthma and may need to be controlled for better management of AD. Further research is required to elucidate the mechanism by which ambient pollutants influence exacerbation of skin symptoms in AD.
Dr. Kenneth Backman of Allergy and Asthma Care comments: “We’ve long known that there are many potential triggers of atopic dermatitis flares, both allergic and nonallergic. This data suggests that outdoor pollution is a potential nonallergic trigger, and may explain some flares that were previously unexplained.”