UK residents have been warned to reduce outdoor activities in certain areas, as the country experiences severe air pollution that is expected to worsen during the week.

The dangerous episode that began at the weekend is caused by a rare combination of Saharan dust, emissions from local vehicles and industries, and particles from continental Europe. It highlights the country’s struggle to control its chronic air pollution, which has remained at illegally high levels since 2010.

According to the environment department, and the Met Office, the national weather service, the pollution is expected to be worst across northern England — including Leeds, Liverpool and Manchester, three cities that have been racing to produce air-pollution control plans in line with a government directive.

On Tuesday morning the air quality in London was on par with Beijing, one of the most polluted capitals in the world, according to data from AirVisual, an app. It prompted the mayor’s office to trigger an alert across the city’s entire transport network.

“The high levels of pollution expected over the next few days is evidence of the scale of London’s air quality crisis and is exactly why the mayor is taking hard-hitting measures to clean it up,” said a spokesperson.

The forecast comes at a time of mounting disputes between city mayors and the central government about how best to tackle the problem — and who should pay for the strict measures required clean it up.

Each year about 40,000 premature deaths in the UK are linked to air pollution, according to a study from the Royal College of Physicians. Air pollution experts say the current pollution episode, which is the worst since the so-called Beast from the East winter storm last March, is likely to increase hospital admissions.

Alexander de Meij, founder of MetClim, an air pollution and weather forecaster, said the current pollution episode could last until Thursday, even longer than the environment predicts. “It is a rare phenomenon because of the Saharan dust,” he said, adding that local pollution and European pollution were contributing factors.

The environment department’s website shows a forecast of “very high” air pollution, a 10 on a scale of 1-10, in parts of northern England on Wednesday. It also shows a band of “high” air pollution. The environment department and the Met Office both declined to comment.

While the current episode is exacerbated by weather conditions, it underscores the UK’s broader failure to bring pollution into line with legal limits.

Over the past few years the government has asked three dozen of the biggest and most polluted cities to figure out how to clean up their air. Some, such as Manchester, Birmingham and Leeds, have proposed plans: these include charging commercial vehicles for access and requests for tens of millions of pounds in state funding.

However, many of the cities have missed deadlines to submit their plans.

Sadiq Khan, the mayor of London, and the heads of more than a dozen other cities say the government is not doing enough to help them comply with the directive, and have asked for a £1.5bn vehicle scrappage fund to help replace the most heavily polluting vehicles.

“We are doing what we can with one hand tied behind our back because of the lack of resources,” Mr Khan told the Financial Times. “Resources are crucial.”

The UK’s air pollution has been at illegally high levels since 2010, primarily due to nitrogen dioxide emitted by diesel vehicles, and the country is facing the threat of EU fines as a result.

However, bringing nitrogen dioxide levels under control often requires reducing the number of diesel vehicles on the roads — policies that can be unpopular in cities where many businesses and families rely on their diesel cars.

© Paul Ridsdale/Alamy

The conflict between the government and the mayors tasked with the clean-up came to a head in Bristol, which last week missed another deadline to submit its air-pollution plan to the environment department.

Officials in the department had threatened Bristol with legal action if it missed the February 21 deadline, and Thérèse Coffey, the environment minister, said she was “disappointed that they failed to deliver”.

Craig Cheney, Bristol’s deputy mayor, said the city was still working on its plan, adding that implementing a daily charge for highly polluting vehicles could end up hurting the poorest residents the most. “We’ve got the responsibility, but we haven’t had any funding,” he said.

The government has a £275m implementation fund, which was recently increased from £255m, to help cities enact their plans and a £220m clean air fund to minimise the impact on local businesses. Mr Khan’s office is not eligible for these funds.

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Asked about the level of funding and support for the local governments, the environment department said: “While air quality has improved significantly in recent decades, we recognise that there is more to do . . . The strategy includes a wide range of measures to improve air quality over the coming years, such as giving new powers to local authorities to tackle air pollution.”

Simon Alcock, the head of UK public affairs at ClientEarth, the legal non-profit organisation that successfully sued the government over its air-pollution plan, said the government had “passed the buck” on improving air quality.

“You have a hodgepodge of cities doing different things,” he said. “We are worried they [the cities] may be hiding behind the lack of action in government to avoid doing things in their cities.”

He added: “It is a public health crisis, it is also a consumer scandal. You can’t tinker at the edges, you need to see some real funding, some real support.”

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