After running our experiment we wanted to be able to corroborate our findings. As the entire borough of Greenwich was designated an LAQM (Local Air Quality Management) zone in July 2001, with constant diffusion tube monitoring since at least 2005, this should have been easy.

However, when we went to check the data we discovered, to our amazement, that the Royal Borough of Greenwich had stopped reporting its data to DEFRA at the end of 2010. We did know that monitoring was still ongoing – we spotted red diffusion tubes at Greenwich’s old locations when we were installing ours. A quick Freedom of Information (FOI) request and chase through What Do They Know gave us access to the data we needed.

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The Greenwich data covered the period from January 2005 until May 2013 – the latest results are above. Results in red break European limits for nitrogen dioxide in the air.

As we suspected, one of the worst offenders throughout the eight-and-a-half year period was the Woolwich Road flyover in east Greenwich – consistently well above the European limit of 40 µg/m3 for nitrogen dioxide.