Ambient air pollutants increase the risk of Immunoglobulin E-mediated allergic diseases: a systematic review and meta-analysis

Immunoglobulin E (IgE)-mediated allergic diseases, including eczema, atopic dermatitis (AD) and allergic rhinitis (AR), have increased prevalence in recent decades. Recent studies have proved that environmental pollution might have correlations with IgE-mediated allergic diseases, but existing research findings were controversial. Thus, we performed a comprehensive meta-analysis from published observational studies to evaluate the risk of long-term and short-term exposed to air pollutants on the eczema, AD and AR in the population (per 10 μg/m 3 increase in PM 2.5 and PM 10 ; per 1 ppb increase in SO 2 , NO 2 , CO and O 3 ). PubMed, Embase and Web of Science were searched to identify qualified literatures. Cochran Q test was used to assess heterogeneity and quantified with I 2 statistic. Pooled effects and the 95% confidence intervals (CIs) were used to evaluate outcome effects. A total of 55 articles were included in the study. The results showed that long-term and short-term exposed to PM 10 increased the risk of eczema (PM 10 , RR long =1.583, 95% CI: 1.328, 1.888; RR short =1.006, 95% CI: 1.003-1.008) and short-term exposed to NO 2 (RR short =1.009, 95% CI: 1.008-1.011) was associated with eczema. Short-term exposed to SO 2 (RR short 1.008, 95% CI: 1.001-1.015) was associated with the risk of AD. For AR, PM 2.5 (RR long =1.058, 95% CI: 1.014-1.222) was harmful in long-term, and short-term exposed to PM 10 (RR short 1.028, 95% CI: 1.008-1.049;) and NO 2 (RR short 1.018, 95% CI: 1.007-1.029) were risk factors. The findings indicated that exposed to air pollutants might increase the risk of IgE-mediated allergic diseases. Further studies are warranted to illustrate potential mechanism for air pollutants and allergic diseases.