approached significancep = 0.06
Mean Der f 1 levels were significantly higher in homes built before 1990 compared to those built after 1990 (47.61 μg/g versus 10.96 μg/g, p = 0.043; 17.54 μg/m 2 , versus 0.2 μg/m 2 , p = 0.012) A sampling surface of carpet, compared to hardwood, predicted dust weight (1.13 g versus 0.30 g; p < 0.001), but not Der f 1 levels expressed as μg/g ( p > 0.6); carpet sampling surface approached significance as a predictor of Der f 1 levels expressed as μg/m 2 ( p = 0.06).