Outdoor air pollution, fluorescent oxidation products and persistent asthma: the EGEA study

Abstract

The biological mechanisms involved in the associations between outdoor air pollution and asthma are poorly known. We studied the associations between long-term-exposure to outdoor air pollution, plasma fluorescent oxidation products (FlOPs), a global biomarker related to oxidative stress and persistent asthma. The study was based on adults with current asthma followed in the Epidemiological Study on the Genetics and Environment of Asthma (EGEA), (EGEA2: 2003-2007, baseline; EGEA3: 2011-2013, follow-up). Air pollutant levels were estimated at the participants’ residential address by ESCAPE (NO2, NOx, PM10, PM2.5) and the French institute of environment (O3). Persistent asthma was defined by current asthma (asthma symptoms, attack or treatment in the past 12 months) at EGEA2 and EGEA3. We conducted mixed models with random effects on city and familial dependence adjusted for age, sex and smoking habits. Among the 201 adults with current asthma at EGEA2 (39 years old in average, 48% men), 160 had persistent asthma at EGEA3. An increase of one interquartile range (IQR) of O3 was associated with higher FlOPs level (adjusted β: 0.02, 95%CI: 0.004–0.04), and with persistent asthma, although this later association was not statistically significant (adjusted (a)Odds Ratio: 1.34, 95%CI: 0.85–2.13). FIOPs were not associated with the other air pollutants. Persistent asthma increased significantly with FlOPs level (aOR: 1.81, 95%CI: 1.06–3.09 per an increase of 1 IQR of FlOPs level). For the first time in adults, FlOPs were associated with O3 and persistent asthma. Our results add evidence on the role of oxidative stress as a biological mechanism involved in the effect of O3 on the respiratory health.