Long-term exposure to airborne particulate matter and NO2 and prevalent and incident metabolic syndrome - Results from the Heinz Nixdorf Recall Study.

INTRODUCTION: Recently, epidemiological studies have found a link between air pollution (AP) and individual components of the metabolic syndrome (MetS), a condition predisposing to cardiometabolic diseases. However, very few studies have explored a possible association between air pollution and MetS.
OBJECTIVE: We analyzed the effects of long-term exposure to airborne particulate matter and NO2 on prevalence and incidence of MetS.
METHODS: We used data of the population-based prospective Heinz Nixdorf Recall study (baseline 2000-2003) to investigate the association(s) between AP exposure and MetS prevalence at baseline (n = 4457) and MetS incidence at first follow-up visit (n = 3074; average follow-up: 5.1 years). Mean annual exposure to size-fractioned particulate matter (PM10, PM2.5, PMcoarse, and PM2.5abs) and nitrogen dioxide (NO2) was assessed using a land use regression model. MetS was defined as central obesity plus two out of four additional risk factors (i.e., elevated triglycerides, reduced high-density lipoprotein cholesterol, elevated blood pressure or elevated plasma glucose). We estimated odds ratios (ORs) of MetS prevalence and incidence per interquartile range (IQR) of exposure, adjusting for demographic and lifestyle variables.
RESULTS: We observed a MetS prevalence of 20.7% (n = 922) and an incidence of 9.7% (n = 299). NO2 was positively associated with MetS prevalence, with an OR increase per IQR of 1.12 (95%-CI 1.02-1.24, IQR = 6.1 μg/m3). PM10 and PM2.5 were both borderline positively associated with MetS incidence, with ORs of 1.14 (95%-CI 0.99-1.32, IQR = 2.1 μg/m3) and 1.19 (95%-CI 0.98-1.44, IQR = 1.5 μg/m3) per IQR, respectively.
CONCLUSION: In summary, we found a weak positive association between air pollution and MetS. The strongest and most consistent effects were observed between NO2 and prevalent MetS.