The Mayor of London issued a "Very High" air pollution alert on Monday, as people living in the U.K. capital suffered from high particulate matter pollution levels.
In a forthright statement, the Mayor or London Sadiq Khan said that the "shameful state of London's toxic air" had forced him to "trigger the first 'very high' air pollution alert" under a new alert system.
"This is the highest level of alert and everyone - from the most vulnerable to the physically fit - may need to take precautions to protect themselves from the filthy air," Khan added.
As of Tuesday, the alert was still in place, with Londoners advised to cut physical exertion outdoors.
According to authorities in London, the higher levels of pollution were a result of cold, calm and settled weather, with low wind speeds resulting in an inadequate dispersal of local pollutants.
Measures taken to raise awareness of the issue include air quality alerts being displayed at 2,500 bus countdown and river pier signs across the city, electronic updates in the entrances of London Underground stations and 140 road-side signs on some roads telling drivers to turn their engines off while stationary.
On Tuesday morning, the Department for Environment Food and Rural Affairs said that air pollution levels for the Greater London area were still "Very High". According to the World Air Quality Index, London's Air Quality Index for fine particulate matter was at 157, higher than Shanghai but lower than Beijing.
The issue of air pollution is a serious one. Last year, a report from the Royal College of Paediatrics and Child Health and the Royal College of Physicians found that exposure to outdoor air pollution was linked to roughly 40,000 deaths every year in the U.K.