As London experiences very sunny weather with high temperatures, the Mayor of London has triggered a ‘high’ air pollution alert for ozone today, for tomorrow (Friday).
The Mayor of London, Sadiq Khan, said: "Air pollutants are reacting with the strong sunshine we are experiencing today leading to high levels of ozone pollution. For that reason, I am issuing a ‘high’ air pollution alert for tomorrow. This means people with heart and lung problems and particularly those displaying COVID-19 symptoms should avoid physical exertion.”
Notes to editors
The Mayor’s Duty Forecaster Service is provided by Imperial College London.
This is the 16th time the air quality alert system has been used since Sadiq Khan became Mayor: one time for ‘Very High’ and 15 for ‘High’, including today’s alert.
Public Health England advice for coping during high temperatures can be read here: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/615548/Beat_the_heat_leaflet_2017.pdf
Why are you declaring a high pollution alert?
This is an ozone pollution alert driven by strong sunshine from dawn to dusk and temperatures reaching 36C. These conditions promote the formation of ground-level ozone as imported and locally emitted pollutants react photochemically in the strong sunshine. We expect tomorrow to be a moderate as weather conditions change.
What is the health advice for ‘high’ pollution?
The Government’s Committee on the Medical Effects of Air Pollutants (COMEAP) advises that adults and children with lung problems, and adults with heart problems, should reduce strenuous physical exertion, particularly outdoors, and particularly if they experience symptoms. People with asthma may find they need to use their reliever inhaler more often. Older people should also reduce physical exertion. Anyone experiencing discomfort such as sore eyes, cough or sore throat should consider reducing activity, particularly outdoors.
When was the last high air pollution episode?
Episodes of pollution with high concentrations occur a few times per year in London, but very high pollution episodes are rare.
The last high pollution episode was on Thursday 25th June 2020. Prior to that, London had not experienced a high or very high pollution episode since 22nd April 2019.