Growing Within Environmental Limits*

Expansion at Heathrow is not a choice between the economy and the environment – it must deliver for both.

*This page contains one (1) question located within the “Have your say” section at the bottom of the page.

As the airport is expanded and redeveloped, there will be an increase in aircraft movements and passenger numbers and, as our operations grow, this will result in some related effects.

The main effects of the growth in our operations relate to:

We propose to manage our growth through the use of an environmental framework. This approach, known as Environmentally Managed Growth, will require us to monitor, review and report on the effects of our growth and, in relation to surface access (traffic), air quality and aircraft noise, identify and commit to defined limits (also described as envelopes).

These limits will set out the maximum level of effect that we will be allowed to have as the airport grows. These clear limits will align with policies in the Airports NPS and would make sure that the tests which the Airports National Policy Statement (NPS) and our Development Consent Order (DCO) consent set out are adhered to into the long term. Whilst some people have doubted that these limits can be observed as the airport grows, we propose to commit to them.

If acceptable to the Secretary of State for Transport, the framework and limits will be part of our approval to grow, and we will be legally bound to remain within the published limits. The consultation document Environmentally Managed Growth explains our proposals in more detail. It includes a draft of the limits that might be adopted.

More detail on the essence of environmental limits

The essence of the environmental limits is explained below.

Surface access

The Airports NPS has two main requirements for surface access which are set out as targets. Heathrow must:

  • increase the proportion of journeys made to the airport by public transport, cycling and walking to achieve a public transport mode share of at least 50% by 2030, and at least 55% by 2040 for passengers; and
  • from a 2013 baseline level, achieve a 25% reduction of all colleague car trips by 2030 and a reduction of 50% by 2040.

As well as these requirements we are developing our plans to address the other Airports NPS requirements to provide mitigation measures to “minimise and mitigate” the effects of expansion on existing surface access and to take “all reasonable steps” to mitigate surface access effects during construction and operation.

Air quality

The Airports NPS makes clear that the Secretary of State will need to be satisfied that, with mitigation, the expansion of the airport will comply with legal obligations for air quality which have been set to protect human health and the environment.

Air quality standards in the UK come from the EU’s Ambient Air Quality Directive which sets limits for the main pollutants such as nitrogen dioxide, carbon monoxide and particulates. The UK must not exceed limits of these pollutants.

The limits we propose will ensure that we only increase the capacity of the airport if it does not:

  • cause a compliant zone to be non-compliant with air quality limit values; or
  • delay the date that a currently underperforming area will achieve compliance with the Air Quality Directive.

These limits will be embedded in our framework for Environmentally Managed Growth.

As well as these limits we will seek to minimise air quality levels below the limit values; this will be done in balance with the wider benefits of growing the airport.

Aircraft noise

The Airports NPS has three main requirements on noise for an expanded Heathrow:

  • Any noise management measures “should ensure the impact of aircraft noise is limited and, where possible, reduced compared to the 2013 baseline assessed by the Airports Commission”.
  • Permission for expansion should not be given unless the proposals:
  • avoid significant adverse impacts on health and quality of life from noise;
  • mitigate and minimise adverse impacts on health and quality or life from noise; and
  • where possible, contribute to improvements to health and quality of life.
  • There must be a progressive improvement in Heathrow’s noise performance.

Our framework proposes that a noise envelope defines limits for these requirements and suggests that may be by reference to contour areas or by using a quota count system. The noise envelope will control total noise emissions from the airport due to aircraft noise and will sit within the framework.

This noise envelope and these limits will be part of our framework for Environmentally Managed Growth. More information on this topic can be found on our noise page.

We also propose that the noise envelope including these limits should be regularly revised to become progressively tighter.

In this way airlines and the airport will be incentivised to develop quieter aircraft and to share the benefit of that with affected communities. To continue to grow our operations, we will need to continually improve our noise performance.


The Airports NPS contains a requirement that carbon emissions from the expansion of Heathrow must not have a material effect on the ability of Government to meet its carbon reduction targets, including carbon budgets.

Carbon emissions need to be considered in the context of the global nature of their effects and the action being taken at an international level by the aviation industry and nationally by the UK Government in their carbon policy. For this reason, the

Environmentally Managed Growth framework is proposing that Heathrow will commit to:

  • the implementation of specific mitigation measures to ensure expansion does not have a material effect on the ability of Government to meet its carbon reduction targets;
  • a mechanism for an ongoing review and reporting of carbon emissions involving independent oversight; and
  • taking appropriate additional action in the event that the above objective is threatened.

Monitoring the limits

To implement Environmentally Managed Growth, we will upgrade our current environmental monitoring regime for traffic, air quality, aircraft noise and carbon emissions to accurately report performance against the limits. Data will be published regularly online and a detailed Annual Monitoring Report will be published showing how the airport is performing in relation to the limits.

Independent scrutiny

We propose that an Independent Scrutiny Panel (the Scrutiny Panel) will be set up to oversee and facilitate the future growth of the airport. We are seeking views on how the Scrutiny Panel will be made up as part of this consultation. It could feature specialist representatives from organisations such as the Heathrow Area Transport Forum, the Heathrow Strategic Planning Group, the Independent Commission on Civil Aviation Noise, and other groups.

The Scrutiny Panel, with the right technical capability and resourcing, will review the Annual Monitoring Report and make sure the various commitments and limits are upheld. The Scrutiny Panel will be given full powers to enforce the limits against Heathrow and to hold us to account for environmental performance by requiring corrective action to be taken or mitigation to be put in place. The graphic above shows how monitoring the limits could work for Heathrow’s expansion.

More information

Our Environmentally Managed Growth document sets out further details, including describing how similar approaches have been taken at other international airports in Europe, how the proposed limits are developed and the way in which monitoring and the work of the Scrutiny Panel will be carried out.

With the framework in place, environmental performance will become central to the day to day operation and growth of the airport. Heathrow’s objective will be closely aligned with the objectives of affected communities – we will have to earn the right to grow.

Have your say

We are proposing to operate an expanded Heathrow within a set of strict environmental limits which would be monitored and enforced by an independent body.

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