Vulnerable Londoners have been warned to reduce strenous physical activity due to high air pollution levels on Friday.
Authorities initially forecast an episode ranked 10 out of 10, which does not happen often in England.
However, this “very high” rating was dowgraded to “high” across most of the capital on Friday morning.
Large parts of North and West London are now ranked eight out of 10 for air pollution, while many other areas face ratings of seven.
This comes with advice from UK Air, part of the Department for Food, Environment and Rural Affairs, on how and when to change behaviours to protect yourself.
When ratings are “high” - which means a rating of seven to nine - such as on Friday, members of the public are told to consider reducing activity, particularly outdoors, if they find themselves “experiencing discomfort such as sore eyes, cough or sore throat”.
Stronger advice is issued for at-risk parts of the population, which includes adults and children with lung problems, and adults with heart problems.
These are told to “reduce strenuous physical exertion, particularly outdoors, and particularly if they experience symptoms”.
Older people are also advised to reduce physical exertion when high air pollution levels are forecast.
London saw an overall high ranking for air pollution just once last year, when UK air ranked levels at eight out of 10 on 31 March.
This happened more frequently in 2020, with the capital given a seven out of 10 ranking on five separate occasions throughout the year, and an eight of of 10 ranking one day in November.
In London, air pollution is “particularly high” between three to eight times a year, according to city hall.
Incidents of very high air pollution - ranked 10 out of 10 on the UK Air scale - happened on several occasions over the last two years, including in Yorkshire and Humberside in February 2019 and in the South East over the Easter weekend of the same year.
As Londoners were initially advised when this was forecast for Friday, all member of the public are advised to reduce physical exertion, particularly outside, in this case.
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