Associations between long-term exposure to PM2.5 chemical constituents and allergic diseases: evidence from a large cohort study in China

Abstract

Background Exposure to air pollutants may cause immune responses and further allergic diseases, but existing studies have mostly, if not all, focused on effects of short-term exposure to PM 2.5 on allergic diseases. Objectives We estimated associations of long-term exposure to PM 2.5 chemical constituents with allergic disease risks and effect modification. Methods We used the baseline of a newly established, provincially representative cohort of 51,480 participants in southwest China. The presence of allergic rhinitis, allergic asthma, urticaria, and allergic conjunctivitis was self-reported by following a formed questionnaire in face-to-face interviews. The average concentrations of PM 2.5 chemical constituents (NO 3 - , SO 4 2- , NH 4 + , organic matter [OM], and black carbon [BC]) over participants' residence were estimated using machine learning models. Logistic regression with double robust estimator and weighted quantile sum regression were used to estimate the effects of PM 2.5 chemical constituents on allergic disease risks, as well as relative importance of each PM 2.5 chemical constituent. Results Per interquartile range increase in the concentration of all PM 2.5 chemical constituents was associated with the elevated risks for allergic asthma (OR = 1.79 [1.41-2.26]), allergic conjunctivitis (1.54 [1.19-2.00]), urticaria (1.36 [1.25-1.48]), and allergic rhinitis (1.18 [1.11-1.26]). NO 3 - contributed more to risks for allergic asthma (weight = 46.05 %), urticaria (…