"With nearly 10,000 Londoners dying early every year due to air pollution, tackling poor air quality is a public health emergency that requires bold action."

Older vehicles that drive in the central London Congestion Charge zone need to meet minimum Euro emission standards or pay an additional daily charge. This is on top of the Congestion Charge.

The T-Charge aims to improve air quality in London, in particular with regard to nitrogen dioxide (NO2) and particulate matter, both of which have an adverse effect on human health.

We already have a number of schemes planned that address this, including the Ultra Low Emission Zone (ULEZ), new licensing requirements to reduce emissions from taxis and private hire vehicles and improvements to our bus fleet. However, more needs to be done to ensure that we continue to tackle pollution effectively and address public health concerns as London's economy and population grows.

The T-Charge (officially known as the Emissions Surcharge) aims to discourage the use of older, more polluting vehicles driving into and within central London.

It is the first step towards the introduction of the Ultra Low Emission Zone (ULEZ), a 24-hour charging zone in central London for older vehicles.