The goal is to meet air pollution limits set by the World Health Organization and the European Union. Just five days into 2017, London had already broken the city's air pollution limits for the year. (London Taxi Company)"Taxi drivers are welcoming them is because they're aware. Since 2000, nitrogen dioxide levels have remained stubbornly above the WHO's legal limit. To further push drivers toward electric vehicles, current Mayor Sadiq Khan is extending Johnson's ultra low emission zone.

Source: CBC News April 14, 2017 09:14 UTC