Bank Holiday heatwave prompts air pollution warnings

Record-breaking May Bank Holiday temperatures have led to warnings high and moderate levels of ozone air pollution in London and parts of the south east of England.

On Monday (7 May) — temperatures in London soared to a high of 28.7C — a record peak for the early May bank holiday, following on from a sustained period of high temperatures across the country.

Soaring temperatures have led to warnings over high levels of air pollutants

This prompted London Air, the capital’s air quality forecasting and monitoring service run by the Environmental Research Group at King’s College London, to warn that the conditions were likely to lead to ‘extensive photo-generation of ozone’ as well as noting that high levels of particulate were expected in some areas.

High ozone levels are most common during summer months in Europe due to the warmer temperatures and higher levels of solar radiation.

Ozone is formed in the atmosphere from emissions of pollutants such as nitrogen oxides from vehicles, organic compounds and methane from agriculture, which react with sunlight. Once formed, ozone can remain in the atmosphere for many days.

Ground-level ozone pollution has been associated with risks including lung inflammation, decreased lung function and an increase in asthma attacks.

In its forecast, issued on Monday morning, London Air stated: “Long sunny periods and possibly the highest temperatures seen on this bank holiday weekend brings extensive photo-chemical generation of ozone.

“The forecast import of particulate has occurred but has stepped up overnight and now brings the chance of ‘High’. With no significant change in the weather into Tuesday this may last right through until a change in wind direction as we go into Wednesday.

“As forecast ‘moderate’ ozone was seen across the south on Sunday but the increased import levels seen in the particulate may also bring additional ozone precursors allowing more significant reactions , and there is a slim chance that ‘High’ may be seen in some locations, with generally ‘moderate’ across London in background locations.“

According to updates on the London Air website this morning, high levels of particulate pollution have been recorded in the capital today, in particular around Farringdon Street, Blackwall and Wembley, but these levels are forecast to drop by tomorrow.


A further warning was issued yesterday by the Department for Environment, Food and Rural Affairs (Defra) when the EU ozone public information threshold of 180 µg/m3 was exceeded in Bournemouth.

The exceedance prompted a warning on the website, in which the government warned those with breathing difficulties to take ‘sensible precautions’ to avoid exposure.

The warning stated: “Public Health England advises that some people are more sensitive to ozone than others and may begin to notice an effect on their breathing. People with asthma are not necessarily more sensitive but, if affected, can use their ‘reliever’ inhaler to alleviate symptoms.

“If affected, people are urged to take sensible precautions. In particular, avoiding exercise outdoors in the afternoon can reduce individual exposure to ozone.

“If the legal threshold for ozone is again breached, further alerts will be issued on our website.”

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