Air pollution warnings have been issued across the UK as local emissions, poor-quality air from the continent, and light winds combine to create potentially hazardous conditions.

Mayor of London Sadiq Khan issued a high pollution alert for the capital in Tuesday, while the government’s air quality information service found particulate matter in the East Midlands and West Midlands to be particularly high.

Similar warnings have been issued this week for towns and cities across the north of England, including Leeds, as well as Scotland and Northern Ireland.

The mayor’s office said there had been poor air quality in London since Sunday evening as a result of local emissions which have failed to disperse and particle pollution from Germany and France.

Pollution in the capital was expected to worsen on Tuesday, prompting an alert will be broadcast across 2,500 bus stop and river pier signs and at entrances to all 270 Tube stations. Roadside message boards on the busiest main roads will flash instructions to drivers to switch engines off when stationary.

New Delhi toxic smog pushes air pollution to peak levels Show all 14 1 /14 New Delhi toxic smog pushes air pollution to peak levels New Delhi toxic smog pushes air pollution to peak levels India's Rashtrapati Bhawan is partly visible due to smog as traffic plies on Rajapth. Smog levels spike during winter in Delhi, when air quality often eclipses the World Health Organization's safe levels AP New Delhi toxic smog pushes air pollution to peak levels Cooler air traps pollutants -- such as from vehicles, building sites and farmers burning crops in regions outside the Indian capital -- close to the ground AP New Delhi toxic smog pushes air pollution to peak levels A man wearing a protective mask walks amidst smog in the early morning in New Delhi Reuters New Delhi toxic smog pushes air pollution to peak levels Indian people receive treatment for respiratory problems at a hospital in New Delhi AFP/Getty New Delhi toxic smog pushes air pollution to peak levels Buildings shrouded in smog Reuters New Delhi toxic smog pushes air pollution to peak levels A combination of pictures showing people wearing face masks to protect themselves against air pollution AFP/Getty New Delhi toxic smog pushes air pollution to peak levels Indian workers are seen in the morning smog as they clean a lane littered with remains of firecrackers AP New Delhi toxic smog pushes air pollution to peak levels Smog envelopes the horizon in New Delhi AP New Delhi toxic smog pushes air pollution to peak levels Motorists on a busy road amid heavy smog AFP/Getty New Delhi toxic smog pushes air pollution to peak levels A man cycles past a government building amid heavy smog AFP/Getty New Delhi toxic smog pushes air pollution to peak levels Commuters are seen amid heavy smog in New Delhi AFP/Getty New Delhi toxic smog pushes air pollution to peak levels An Indian shepherd walks along his herd of sheep amidst heavy smog AFP/Getty New Delhi toxic smog pushes air pollution to peak levels A train moves through heavy smog EPA New Delhi toxic smog pushes air pollution to peak levels A pedestrian crosses a road near the Indian President's house AFP/Getty

It is the 101th time the air quality alert system, which also involves social media and text alerts, has been used since Mr Khan became mayor in May 2016.

Last year he announced the launch of an ultra-low emission zone, in which drivers of polluting vehicles pay extra charges, in a bid to tackle toxic air.

Tuesday was forecast to bring continued local emissions and the arrival of air from the northern Europe that is even more toxic because it is bringing pollution from a working weekday rather than weekend.

A cloud of Saharan dust was also predicted to worsen air quality in the coming days.

Adults with heart or lung problems and children with lung problems are warned to reduce strenuous physical exertion, particularly outside, during high pollution, while people with asthma may need to use their inhalers more often.

Support free-thinking journalism and attend Independent events

A spokeswoman for the Mayor of London said: “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.

“April’s launch of the world’s first Ultra Low Emission Zone (ULEZ) in central London is expected to reduce harmful emissions in the zone by around 45 per cent.

“The Mayor is also cleaning up the capital’s bus and taxi fleets, rolling out rapid charging infrastructure and delivering improvements to schools in some of London’s most polluted areas.”