Also my more more detailed view of Bristol
The data to produce these graphs is taken from:
Air Quality Open Data Platform
Worldwide COVID-19 dataset
I have tried to take two representative weeks for each location before and after their national lockdowns. What I find interesting is often there is an increase in particulates after lockdown whereas the nitrous oxides decline as is expected. Estimates for Bristol in the UK are for road traffic to have decreased by almost 80% since lockdown but this is not reflected in the post lockdown figures and I suspect this is typical of the other cities so are vehicles really the villains they are made out to be and will a ban on diesels be as beneficial as it is hoped?
Professor Roy Harrison is Queen Elizabeth II Birmingham Centenary Professor of Environmental Health at the University of Birmingham, and kindly provided this explanation for the particulates analysis.
“The period immediately after lock-down in the UK was characterised by anticyclonic conditions that brought air heavily polluted with secondary PM to the UK. Since primary vehicle emissions are only a modest contributor to urban PM concentrations, most UK sites saw an increase in PM levels.”
Particulates are the most harmful form of air pollution due to their ability to penetrate deep into the lungs and blood streams unfiltered, causing heart attacks, respiratory disease, and premature death. – wikepedia
See also Paul Homewood’s Blog featuring other aspects of weather related problems.
And Yes Milan is high !
This UK government analysis is interesting as it shows road traffic isn’t a massive contributor to emmissions.
So it seems despite massive decreases in traffic the expected reductions in pollution are not following the trend.
Adrian Kerton 