A new website lets Londoners see levels of pollution on any street. 'Airview' uses monitoring stations across the capital to visualise the air we breathe.
Animation above shows pollution on Oxford Street (courtesy airview.blueair.com)
Last week London's mayor Sadiq Khan issued the first "very high" pollution alert.
The capital was hit by extreme particulate pollution which built up in the long period of cold settled weather.
Find out the pollution level for your part of London here.