Synergistic Association of House Endotoxin Exposure and Ambient Air Pollution with Asthma Outcomes

Rationale: House endotoxin and ambient air pollution are risk factors for asthma; however, the effects of their co-exposure on asthma are not well characterized. Objectives: To examine potential synergistic associations of co-exposure to house dust endotoxin and ambient air pollutants with asthma outcomes. Methods: We analyzed data from 6,488 participants in National Health and Nutrition Examination Survey (NHANES) 2005-2006. Dust from bedding and bedroom floor was analyzed for endotoxin content. The Community Multiscale Air Quality (CMAQ) and Downscaler (DS) data were used to determine annual average particulate matter ≤2.5 μm (PM2.5), ozone (O3), and nitrogen dioxide (NO2) exposures at participants’ residential locations. The associations of the co-exposures with asthma outcomes were assessed and tested for synergistic interaction. Results: In adjusted analysis, PM2.5 (CMAQ) (OR 1.12, 95% CI: 1.07-1.18), O3 (DS) (OR 1.07, 95% CI: 1.02-1.13), and log1010-NO2 (CMAQ) (OR 3.15, 95% CI: 1.33-7.45) were posit...