London mayor Sadiq Khan told MPs last week that the T-Charge introduced in October was a loss maker for TfL but is important in changing behaviour and a precursor to the Ultra Low Emission Zone (ULEZ).

“Half of the bad-quaity air in London comes from transport, and 88% of that comes from diesel. Roughly speaking, 34,000 vehicles a month would be caught by the T-Charge. Not all of them are coming to London every day and paying the additional fee, which is good – we are not trying to make money; we are trying to change behaviour.

“The ULEZ will initially cost us. Over a period of time it will bring in revenues, but we will ring fence that money for clean air. We will not divert that money anywhere else,” Khan told members of the Air Quality Inquiry.

Khan also claimed businesses were broadly supportive of the earlier ULEZ start date, which had been consulted on extensively and had come forward by 17 months, despite concerns raised by the RHA and FTA.

He added that TfL would consult on extending the zone to all of London for HGVs shortly.

The RHA previously stated that the early launch date for the ULEZ is a “means of quickly bringing in revenue to cover the mayor’s other plans for the city”.

Chief executive Richard Burnett also warned that half the UK HGV fleet may not be Euro-6-compliant by the time it comes in.

While Khan did not speak about HGVs, he conceded that there will be an impact on vans, something the FTA had warned about.

He told MPs the first stage of the ULEZ would likely affect 70,000 vans that are not Euro-6 compliant, “which is why I’ve been lobbying government for a diesel scrappage scheme”, he added.

Khan said a targeted scheme to help poorer residents and smaller business would cost the government £500m over two years.

“This means that businesses could get the assistance they need to move away from the most polluting vehicles,” he said.