The mayor wants greater powers to enforce compliance with the standards of the non-road mobile machinery low emission zone (NRMM LEZ), a scheme that uses planning powers to impose minimum emissions standards for machinery used on construction sites.

Although London has tough rules designed to ensure only modern low-emission machines are used, the mayor does not believe the scheme is being enforced properly because of stretched resources within local authorities.

Non-road mobile machinery such as construction excavators and bulldozers are the second largest source of ultra-fine particulate matter (PM2.5) emissions in London and the fifth largest source of oxides of Nitrogen (NOx). Sadiq Khan has said that tackling London’s air pollution is one of his top priorities.

Since September 2015, non road mobile machinery with engines of a net power from 37kW and 560kW used on any major development within Greater London is required to meet Stage IIIA emissions regulations as a minimum, or retrofit best available technology. Machines within the central activity zone or Canary Wharf have to meet Stage IIIB as a minimum. From 2020 any development site in Greater London will be required to meet Stage IIIB. Central London and Canary Wharf will need to meet Stage IV.

The mayor has already given local authorities £400,000 to enforce the zone but he wants to ensure that boroughs, or GLA bodies, have greater ability to apply the standards.

He also wants the rules of the NRMM LEZ to be applied retroactively to existing planning permissions and to other users of NRMM as the current regulations mean that more than 1,000 sites are not registered and activities such as roadworks and events are not covered at all.

Sadiq Khan also wants either the mayor, or another appropriate authority, to have the power to set minimum emission and technical standards for all NRMM used in London. This could be done by amending the GLA Act so that the mayor can use their powers to regulate NRMM in the same way as for road vehicles.

To support these powers, Mr Khan wants a DVLA-style national database for NRMM.

Sadiq Khan has written to environment secretary Michael Gove setting out the additional powers that he believes are required.

Mr Khan said: “Non-transport sources contribute half of the deadly emissions in London so we need a hard-hitting plan of action to combat them similar to moves I am taking to reduce pollution from road vehicles.

“With more than 400 schools located in areas exceeding legal pollution levels, and such significant health impacts on our most vulnerable communities, we cannot wait any longer and I am calling on government to provide the capital with the necessary powers to effectively tackle harmful emissions from a variety of sources.”