London heat wave leads to air quality concerns

High levels of ozone forecast in outer London as hot weather fuels air quality concerns, writes Will Date.

High levels of ozone have been forecast for London, leading to fears that public health could be affected.

According to the website Air Text, which forecasts air quality levels in the capital, high readings of ozone were expected in areas of outer London today. However, air quality readings taken by Defra are yet to show any significant levels of ozone across the city.

Ozone can be harmful to humans as the ozone molecule consists of three oxygen atoms bound together, making it a powerful oxidising agent which can damage biological membranes including the lining of the lungs.

Air quality in London is under scrutiny as a result of hot weather

Simon Birkett, founder of the Clean Air in London campaign believes that the heatwave currently sweeping the capital is largely to blame for the high incidence of ozone being forecast.

He said: “It has been unusually hot for May and London is due to hit 28 or 29 degrees at some point today. Smog can be caused by a combination of the low level of wind and the sunshine. What is happening is that there are high levels of ozone in outer London, not helped by sunshine beating down on the nitrogen dioxide from traffic pollution in inner London.”


Dr Christine McHugh, assistant director at Cambridge Environmental Research Consultants which runs the Airtext service alongside London councils, explained that high ozone readings can be common at this time of year.

She said: “Every spring it is not unusual to get readings of high ozone levels. In the heat these can be caused by a photochemical reaction which brings the molecules down into the lower atmosphere. Some people can be affected, but higher readings have been taken elsewhere in Europe than in London.”

And, according to Mr Birkett, high ozone levels are likely to be one reason why London Ambulance Service staff were called out 1,345 times on Tuesday (May 22), the Service’s busiest weekday in history. Assistant Chief Ambulance Officer John Pooley confirmed that a large proportion of these calls were for people suffering from chest pains and breathing difficulty which he attributed to the hot weather.


Mr Birkett has hit out at the lack of publicity about London’s high ozone levels, claiming that Defra has broken assurances made in Parliament that it would publish details of any smog episodes occurring across the country.

He said: “There is no question people should be warned. Quite frankly, this is a massive public health failing by the government and the Mayor. Both say that they want the public to be made more aware of pollution, but they are going out of their way not to do so. I think they are avoiding the issue and trying to keep it out of the public eye.”

Speaking to AirQualityNews, a spokeswoman for Defra said that as yet only moderate levels of ozone had been recorded across the capital by the government and any high ozone readings would be publicised immediately.

She said: “If there is an episode of smog we would issue alerts in the form of an information bulletin, but we haven’t reached high ozone levels yet. Defra would also issue a bulletin at the beginning of the smog season, although there is no legal requirement for us to do so. We have monitoring stations across the country which are updated throughout the day.”

(Amended May 31. Note: The airTEXT services forecasts air quality, rather than monitoring air quality).

Related links

Cambridge Environmental Research Consultants
Clean Air in London


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Colin Roberts
Colin Roberts
12 years ago

Thanks for starting this information service. It is especially important for London as we have such awful air quality and the GLA is failing to protect us.

12 years ago

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