In UK, a very high air pollution warning has been issued for London for the first time under a new alert system. Warnings are being issued at bus stops, roadside signs and Tube stations under the new system set up by London Mayor Sadiq Khan. <br/><br/>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.