Fig. 4From: Evaluation of associations between asthma exacerbations and distance to roadways using geocoded electronic health records dataDaily 8-h maximum PM2.5 levels from 2014 to 2019. The recommended exposure limit for PM2.5 is 35 μg/m3. There was only one period – fall of 2017, corresponding to wild fires in the region – that exceeded this thresholdBack to article page