So, what's this?
It's some of the data you can get from here:
London Air Quality Network :: the comprehensive source of information about air pollution in London
www.londonair.org.uk
Which I have posted about before on this thread. Here's the graph OneLambeth_Justice have posted on twitter:
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They are saying that this somehow shows that LTNs have made air pollution worse on this site, for this particular measure. Well, I can replicate their graph, for March 2020 - April 2021, as per my link above, and it looks like this:
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Slightly different formatting but essentially the same graph. They seem to be pointing at the peak in November 2020. Sure, that was after the LTNs around Brixton were mostly in. And it was sort of between lockdowns.
So shall we see what the same period, for the previous years look like?
First, March 2019 - April 2020:
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Then, March 2018 - April 2019 (unfortunately a chunk of data missing):
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Finally, March 2017- April 2018:
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What are they on about? There are significantly worse levels measured during all of these previous years.
And what if we look at the bit they've conveniently missed off their graph - which is what's happened since spring/summer 2021, as restrictions have been lifted, with LTNs pretty much fully implemented? Do we see the graph line rising and rising? No!
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In fact we see levels between June-September 2021 dropping to generally lower than are seen in all of the previous years for the same months ... with the possible exception of 2020, when the LTNs were already in.