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Boilers, combined heat and power plant (CHP) and diesel generators all contribute to air pollution in the Square Mile.

Deconstruction and construction activities also can negatively impact air quality if not appropriately managed. Wood burning outside the City boundary also impacts on London PM10 levels.

The following sections show how building​s and development activity can reduce their impact on air quality and reduce exposure to air pollution. This includes:

  • using technology that doe​s not require combustion
  • if boilers are required, low NOx plant should be installed (<40mg/kWh)
  • if CHP is required, low NOx plant must be used and it's impact on air quality must be assessed before it's installed (as detailed in the City of London Air Quality SPD)
  • solid fuel such as wood, biomass and coal are discouraged due to the negative impact on particulate levels
  • diesel generators should not be used to provide electricity to the National Grid or to a building other than in an emergency
  • chimneys associated with all combustion plant must terminate at high level, in order to aid dispersion, and away from places where people spend time
  • all non-road mobile machinery, including that used in street works, should meet the latest Euro Standard as a minimum​​​

Air Quality Supplementary Planning Document (SPD)

So developers can minimise emissions and exposure to air pollution, the City Corporation has produced an Air Quality SPD. It was formally adopted on 25 July 2017 following public consultation. The City of London Air Quality SPD (3MB) is accompanied by a:

The SPD provides City Corporation detailed guidance relating to the GLA's London Plan Air Quality Policies and the City Corporation's Local Plan Air Quality Policies.

An Equalities Impact Assessment (200KB)and Strategic Environmental Assessment Screening Statement (60KB)​ have been produced which demonstrate the SPD has a largely neutral or positive impact.

Additional City Corporation SPD's and consultations can be found on the Supplementary Planning Document webpage.

Chimney Height Approvals and Generator Emissions​

Several measures are in place to minimise boiler, CHP and generator emissions.​ Newly installed boilers and CHP must meet low NOx emission​ limits; see the City Corporation's Air Quality SPD (above) for more guidance. The City of London has also produced a short guidance note aimed at minimising emissions from standby generators (270KB).

Clean Air Act 1993

Some chimneys serving furnaces or boilers require approval from the City of London Corporation before they are used. This is to ensure that the proposed chimney is high enough to allow adequate dispersion of the flue gases. Approval is required for chimneys serving commercial or industrial furnaces or boilers used to burn the following fuels:

  1. Pulverised fuel
  2. Any other solid matter at a rate of 45.4 kilograms/hour or more.
  3. Any liquid or gaseous matter at a rate of 366.4 kilowatts/hour or more

Chimney height approval is required in addition to any other necessary permissions e.g.​ planning permission or building regulation approval.

Chimney height applications

Download a chimney height application form (44KB) or contact the City of London for an application form. The City of London will to determine the application within 28 days of receipt. There is no charge.

Applicants should use the 3rd Edition of the Clean Air Act Memorandum on Chimney Heights for guidance in order to establish the height of any proposed chimney. This document is published by Her Majesty's Stationery Office (HMSO).

Minimising impact during Deconstruction and Construction - NRMM and Code of Practice

The City Corporation has recently revised it's Code of Practice for Deconstruction and Construction. There is a dedicated air quality chapter which incorporates City Corporation and appropriate Greater London Authority requirements.

The City Corporation's Code has recently been updated and the document​ includes the requirement for appropriate Non Road Mobile Machinery engines to meet the Euro Stage IIIB and to be registered on the dedicated NRMM website. A NRMM Practical Guide (4MB) has also been produced which provides further guidance.

Further details regarding managing construction site emissions and NRMM emission research projects can be found via the London Low Emission Construction​ Partnership website.

Environmental Permits

Certain industrial activities have the potential to contribute to air pollution. Local authorities, along with the Environment Agency, are required to regulate them to ensure that they are using best practice to minimise emissions to air. This responsibility is detailed in the Environmental Permitting (England and Wales) Regulations 2010.

Part A1 processes

Part A1 processes are very large operations such as power stations. These are regulated by the Environment Agency. There are no Part A1 processes in the City of London.

Part B and A2 processes

Both Part B and Part A2 operations are regulated by local authorities. The Part B regulatory system is known as Local Authority Pollution Prevention and Control (LAPPC). The Part A2 system is Local Authority Integrated Pollution Prevention and Control (LA-IPPC). Local authorities deal with about 80 different types of installation including:

  • dry cleaning
  • vehicle respraying
  • furniture manufacture
  • cement batching
  • petrol stations

There are currently three Part B regulated processes in the City of London. They are listed below. Further information about these operations has been placed on a public register, which is free to view at the City of London Walbrook Wharf Office on Upper Thames Street.

Part B regulated processes operations
Reference Operator Address Date of issue
01/DC/CL City Slickers​ 34 - 36 Lime Street, London EC3M 7AT​ 5 April 2007
02/DC/CL​ City Slickers​ 57-60 Aldgate High Street, London, EC3N 1AL ​ 5 April 2007
04/DC/CL Four Seasons 10 Trinity Square, London, EC3N 4AJ 12 April 2019

If you intend to operate a process that requires a Part B or Part A2 authorisation, you will need a permit. Please contact the Air Quality Team.

Smoke Control in the City of London

The City of London is a Smoke Control Area, under Section 18 of the Clean Air Act 1993; see other Smoke Control Areas across London and the UK. If you use an open fire, stove, or other wood or coal burning appliance in the City of London, read this practical guide (325KB).

In a Smoke Control Area, it is an offence to emit smoke from the chimney of a building, a furnace or any fixed boiler. It is also an offence to use an 'unauthorised fuel' unless it is used in an 'exempt' appliance; the fuel used must also be the fuel specified for that exempt appliance. As well as a list of authorised fuels, the list of exempt appliances can be found on the Defra website.

Restaurant grills and log burning ovens: Charcoal grills are not listed as an exempt appliance and only certain charcoal is listed as an authorised fuel. However, a gas fired or electric grill is permitted. Traditional pizzas can also be cooked inside an ‘exempt’ appliance.

The maximum fine is £1,000 for each offence.

In addition, any appliance producing cooking fumes must be appropriately ventilated to outside air. Appropriate ventilation is one which doesn’t cause a nuisance to neighbours; this generally means filtered mechanical extract ventilation with an outlet at high level.

If you need more information please visit the website links above or email the Air Quality Team

Further Inform​ation and Contact Details

​The Institute of Civil Engineers has produced a report into Civil Engineering Solutions to London's Air Pollution (2.5MB).

Further details regarding managing construction site emissions and NRMM emission research projects can be found via the London Low Emission Construction​ Partnership website.

Contact the City of London:

Switchboard: 020 7606 3030

Email: Air Quality Team: