Edinburgh Council continue to deny the evidence of their own eyes - by saying traffic does not got down the centre of the street.
Why? Because the distance from the kerb matters a lot .
Why? This extract from an email to senior colleagues by the head of the Council's Scientific Services Department (released under FoI) makes clear.
".......The net effect of using the national bias factor and the larger diffusion factor is that the calculated levels of N02 at the building facade will be greater than the value which CEC would calculate, and the combined effect is more likely to tip the value over the air quality maximum."
(the further traffic really runs from the kerb, and the parked cars, the larger the difffusion factor--------By pretending the traffic is closer than it is, the diffusion factor is reduced and the air pollution recorded in the final 'corrected' figures then comes out as a lower number)
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