IBM says that Canterbury’s air quality is good — but it’s not


The air quality in Canterbury is always “Good”. That is what my smartphone tells me every day. Through an IBM subsidiary,, it also gives me a numerical measure — and this is nearly always top of the class (1) although occasionally it slips to 3. By contrast, when I was in Germany in the Spring readings were usually around the 50 mark, and described as ‘Medium’.

But when I do my own research in Canterbury I get a different answer. I have one friend who splits her time between here and a village on the coast in Fife. She breathes well in Scotland but her asthma often returns after a couple of days spent in Canterbury. She is not alone. Retired St Stephen’s GP David Pratt noticed a similar kind of pattern amongst the people he treated back in the 1990s. He began to speak out publicly about air quality over 20 years ago. The reason, he explained to me recently, was that he had “become concerned at the demonstrable and recorded deterioration in respiratory function in our asthmatic patients with time as the traffic increased through St. Stephen’s to Canterbury”.

And then I spoke to our world expert based down the road — Stephen Peckham, Director of the Centre for Health Services Studies, at the University of Kent. Professor Peckham runs three air quality monitoring machines in our district (two in Canterbury, one in Whitstable). He does not describe our air quality as “Good”. And he is particularly concerned at the effect on younger generations. He told me: “Children are exposed to poor air quality throughout the centre of Canterbury. This means they will have smaller, less effective lungs as adults.”

Research by Queen Mary, University of London among 2,000 eight- and nine-year olds in four London boroughs has shown that they typically have “a loss of 5 per cent in lung capacity”. Research from California found that there are five times as many 18-year olds with a 20 per cent reduced lung capacity in polluted areas. Looking at the readings from Professor Peckham’s recorders, I find that on the day I looked (Tuesday, August 6), Nitrogen Oxide emissions (NOx) hit a maximum of 208 in St Stephen’s that morning — five times the legal level.*

The problem here is that most people do not know how to understand these readings (which, by the way, measure the presence of these pollutants in millionths). But the Canterbury results are troubling. The government sets the annual average annual legal threshold at 40 — but this includes the night time when levels are close to zero. Research is increasingly suggesting that children’s lungs are permanently damaged at levels of 10 and above.

Local authorities have a legal duty to respond when NOx levels exceed the government’s legal threshold. But they do not have to take action over PMs and Ozone. (See the note at the bottom of this article for PM and Ozone readings.) On PM 2.5s there is no known safe level: the World Health Organisation says that there is “little evidence to suggest a threshold below which no adverse health effects would be anticipated”. The Queen Mary research points to PMs, alongside NOx and Nitrogen Dioxide, as being a cause of reduced lung growth.

Meanwhile, Ozone affects lung function in higher concentrations. And there is no legal duty here on councils. Canterbury is one of the few UK locations which regularly breaches the UK hourly limit (of 180) — because of its high levels of sunshine and traffic, and its location in a bowl. Daily levels often reach 100, a level which can produce symptoms for asthmatics and others who are sensitive.

Canterbury is not alone in Kent. Maidstone’s streets are the fifth most polluted outside London, according to a February 2019 survey from Friends of the Earth. Poor air quality is a disease of prosperity. We are poisoning ourselves by our emissions, particularly from diesel vehicles.

So we need major changes here. We need more measuring gadgets — particularly by roads where emissions push up NOx levels. We need this information put out on an app in a format that people can understand so that we can see which streets to avoid at any given time. We need better public transport at a lower cost to users. We probably need free public travel, if we are to encourage drivers out of their cars. And that would mean a reorganisation of public finance including the introduction of substantial travel grants from central to local government. If that sounds like the tail wagging the dog, it is not. There is nothing more important, if you think about it, than ensuring that our children grow large, healthy lungs.

And, finally, we need smartphones to get more accurate information. Air quality stats are not like temperature readings. Temperatures generally remain the same across broad areas but, as meteorologists know, a reading taken in a park can be very different to that from a bus stop 100 metres away. In this case, the monitor is in a leafy area of the old Chaucer Tech on Pilgrims Road which doubles as a police dog training ground, just opposite King George’s Field. I went there on Thursday, 8 August at noon. While Ozone on this measure was put at 40, it was registering over three times that level (133) on Wincheap. The smartphone was scoring Canterbury at 2 — “Good”.

They say that no-one ever got fired for hiring IBM. In this case, whoever fires IBM should be promoted.

  • Other readings (in parts per million): St Stephen’s: The reading for low level ozone was 123 in St Stephens. And the small particulates — PM 2.5 — fluctuated between 4 and 15.
  • At St Dunstan’s, the NOx readings were lower (a maximum of 82) than in St Stephen’s. The Ozone reading was higher (between 4 and 161). The  PM 2.5 reading was also higher (between 3 and 38).


  1. Thank you and congratulations Neasa for writing this article. It is excellent and one of the most important articles ever to appear in the Canterbury Journal .

    I hope it is widely read. particularly by people who have naively believed the complacent drivel spewed out in previous years in the Council chamber by those who would claim by the mischievous and lazy use of 24/365 annual averages that there is no significant AQ problem in Canterbury

    For far too long representatives of various vested commercial interests have sought to downplay/deny the hard evidence collected by Prof Peckham and his team..

    I look forward to seeing Stephen’s data incorporated in Council reports.from now on.

    The new regime at CCC , pleasingly, appears to be accepting that there is now real urgency about these issues. Long may this offer of constructive engagement with the local community, following the welcome declaration of a Climate Emergency and the objective of carbon neutrality by 2030 ,continue..

    I do so agree also with the point about visibility of data for the public to digest.

    Data about sea water cleanliness is there for all to see at the beaches.

    Why not AQ stats in public places?


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