'Cleaner Air for London' are warning of unusually high levels of pollution in London today.

Experts from London Air at King's College London, released this explanation:

Over the weekend the air arriving will have mainly been over the North Sea for the last few days and will bring with it little pollution, however by Monday this path will have changed dramatically and will have followed a long track over continental Europe possibly bringing with it industrial and urban emissions. In the sunny conditions this will provide the base for photochemical reactions and both ozone and particulates may become 'moderate', with the chance of 'high' particulate depending on the exact make up of the imported pollution and strength of sun.

Advice for the general public is that anyone who experiences discomfort such as sore eyes, cough or sore throat should consider reducing activity particularly outdoors.

People with lung or heart problems, should reduce strenuous physical exertion, particularly outdoors, and particularly if they experience symptoms. People with asthma may find they need to use their reliever inhaler more often.