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Table 2 Distribution of PM, NO 2 and traffic exposure in rural and in urban areas

From: Air pollution and subclinical airway inflammation in the SALIA cohort study

  Total area (N = 402) Rural area (N = 190) Urban area (N = 212) p-Valuee
Variable Median (IQR) Median (IQR) Median (IQR)  
Nearest monitoring stations (Five-year mean) a     
NO2 [μg/m3] 30.8 (13.2) 20.2 (0) 33.4 (2.6) < 0.0001
PM10 [μg/m3] 25.3 (3) 25.2 (0) 28.2 (3.4) < 0.0001
LUR-modelled exposure b     
NO2 [μg/m3] 26.0 (9.42) 23.0 (2) 31.9 (10.3) < 0.0001
PM10 [μg/m3] 26.4 (2.26) 25.6 (0.89) 27.7 (2.7) < 0.0001
PM2.5 [μg/m3] 17.4 (2.06) 17.0 (0.42) 18.9 (1.7) < 0.0001
PM2.5 absorbance [10−5 m−1] 1.38 (0.44) 1.20 (0.13) 1.62 (0.47) < 0.0001
Traffic loadc [vehicle*km/day] 0 (990) 0 (0) 0 (1330) 0.0003
  % % %  
Distance < 100 md 19.1 14.7 23.1 0.0331 f
  1. aFive-year mean of 2003 – 2007 from the nearest monitoring station of the State Environment Agency covering the area in an 8-km grid (1 station in Borken, 5 stations in Ruhr-Area).
  2. bLand-use regression modelled exposure using data from a measurement campaign (2008/2009) gained in the framework of the EU-ESCAPE study for assessment of individual long-term exposure (Modelling based on the measurements from 40 stations for NO2 and 20 stations for PM).
  3. cTraffic volume within a 100 m buffer around the home, calculated as the sum of the products of the number of vehicles from all roads with ≥ 5,000 vehicles per day multiplied with the street section length in the 100 m buffer.
  4. dDistance of residential address < 100 m from major road with more than 10,000 vehicles per day.
  5. ep-Value of Wilcoxon test for the difference of means between rural and urban area.
  6. fp-Value of χ2-test for the difference between rural and urban area.