LONDON (AP) — Cold, still weather in London prompted the mayor to issue a "very high" air pollution alert for the first time Monday, while thick freezing fog caused numerous flight delays and cancellations at London Heathrow and other area airports.
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 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 Tuesday.
Separately, travelers were advised Monday to check their flight status before going to the airport after roughly 100 flights were cancelled and many more were delayed.
The Met Office forecasting service said visibility at Heathrow had been reduced to roughly 100 meters (110 yards), leading to an overall slowdown in operations.
It issued a severe weather warning for London and most of southern England as driving conditions were also hazardous and slippery.
Conditions at Gatwick, London City and Stansted airports were also difficult with limited visibility.