Cold weather leads to ‘very high’ air pollution for London

Cold weather thought to have contributed to ‘very high’ levels of air pollution measured in capital today (December 12)

A sustained period of cold weather across the UK has seen air pollution reach ‘very high’ levels in London and South Wales – the fourth time it has reached this level in 2013.

Defra has reiterated its health advice to those affected by the pollution episode, advising adults and children with lung or heart problems and the elderly to avoid strenuous activity.

The capital has been shrouded in fog on both Wednesday and Thursday mornings

The capital has been shrouded in fog on both Wednesday and Thursday mornings

It has also advised people to reduce physical exertion, particularly outdoors, if experiencing symptoms such as a cough or sore throat.

Defra’s pollution forecast for South Wales has been downgraded to ‘high’ this evening, but remained ‘very high’ in London as of 5pm.

Meanwhile, ‘moderate’ levels of pollutants PM10 and PM2.5 were recorded at a number of monitoring sites located in roadside and industrial locations by the London Air Quality Network. One kerbside location in the City of London also measured a ‘high’ reading for PM2.5.


Evidence of the conditions have been visible across the capital with a thick layer of fog shrouding the city on both Wednesday and Thursday mornings. This has also lead to travel delays at some airports and train stations across the city.

In its air quality forecast summary, published at around lunchtime today (December 12), the Department stated: “Cold weather will cause moderate pollution in some areas and high and very high levels of particulates are likely in London, South East and South Wales this morning.”

Its outlook for the week added: “Cold weather may cause localised moderate or high levels of pollution near busy roads but levels are expected to be low in most areas. Saharan dust deposits may affect any part of the UK towards the end of the week but this is unlikely to affect pollution levels.”

It is thought that showers expected to happen on Friday and Saturday will ease some of the pollution around the capital.

Defra forecasts also highlighted Saharan dust deposits as being likely to affect the UK towards the end of the week, but states that this is ‘unlikely to affect pollution levels’.

According to campaign group Clean Air in London, there have been 14 smog episodes in 2013, compared to 12 last year. Director and founder of the campaign group, Simon Birkett, has previously called for a government warning to be issued every time high pollution levels are monitored.


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Roland Gilmore
Roland Gilmore
10 years ago

Rather than blaming “cold weather”, DEFRA should know that an essential condition for fog to form is a lack of wind (to blow the pollution away). Simon is quite right to insist that DEFRA issue government warnings when pollution levels look likely to become “high”. They have the modelling software so it is not an onerous task.

10 years ago

I don’t quite understand. Do you mean that people turned their heating up higher than usual owing to the cold, thus creating more fine particle pollution – which, together with road traffic emissions, lingered in the air as there wasn’t much breeze to disperse it? If so, then don’t you mean smog not fog?

And why weren’t UK towns and cities further north affected by this “cold weather-plus-pollution” event?

I’m curious! Thank you again for the excellent site that you produce. Josephine

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