A very high air pollution warning has been issued for London for the first time under the new system set up by London Mayor Sadiq Khan.
The rise has been attributed to cold, calm and settled weather, meaning winds are not dispersing local pollutants. A spike in pollution on Sunday was the highest level recorded since April 2011.
Thick freezing fog caused numerous flight delays and cancellations at London Heathrow and other area airports, reports said.
The London air monitoring team at King's College London said pollution in the capital was at ‘black’ -- the highest level, meaning people should reduce physical exertion outdoors.
It said that the cold weather and absence of wind allowed emissions across the whole of southeast England to build up over the weekend. The rise in pollution was caused by a combination of traffic pollution and wood burning, it added.
Officials warned that many other places across Britain were also suffering from high levels of pollutants known as particulate matter and the problem is expected to continue.
The Met Office forecasting service said that visibility at Heathrow had been reduced to roughly 100 meters (110 yards), leading to an overall slowdown in operations.
Conditions at Gatwick, London City and Stansted airports were also difficult with limited visibility.
