Mayor Sadiq Khan has triggered a “high” air pollution alert in London.
It is the seventh time the air quality alert has been used in 13 months, once for “very high” and six times for “high”.
The alerts will see warnings displayed at bus stops, river piers and dot matrix message signs on the busiest main roads.
Mr Khan said: “The shocking and illegal state of London’s filthy air means once again I am triggering a ‘high’ air pollution alert today under my new comprehensive alert system.
“Safeguarding the health of Londoners from toxic air is an important priority for me as mayor. I am implementing the boldest policies of any city in the world, which includes introducing the T-charge next month to tackle emissions from the oldest polluting vehicles and bringing forward the Ultra-Low Emission Zone and even tighter standards in April 2019.”