Figure 4From: Use of passive diffusion sampling method for defining NO2 concentrations gradient in São Paulo, Brazil NO 2 concentration according to traffic counting (log). r = 0.65 p < 0.001 for periods 1 + 2. r = 0.75 p < 0.001 for period 1. r = 0.71 p < 0.001 for period 2.Back to article page