Academic research funded by NERC looking at better scientific data on Heathrow area NO2 pollution



The BBC jumped the gun on this story – reporting that the study implies there would be no problem with air pollution from a Heathrow runway.  That is not a conclusion that can be justified from the study, as yet.  Below:

Heathrow runway ‘within EU pollution laws’

The study measured poisonous nitrogen dioxide (NO2) levels using 40 sensors in and around the airport.

It then used modelling to predict what would happen in the future.

Ministers will decide within weeks whether to enlarge Heathrow or rival Gatwick and the environmental impact will play a big part in that decision.

The work was led by the University of Cambridge and has no formal links to any airport or the government.

Prof Rod Jones from the University of Cambridge told the BBC: “If there is the development of a third runway, we expect there to be a marginal increase in NO2 coming from the airport itself, but that would be against the background of reduced NO2 from other traffic, because of Euro 6 engines and electrification of the traffic fleet.”

In other words, it comes down to traffic on the roads, rather than planes in the air, because that is where the bulk of the poisonous nitrogen dioxide gases come from.

As new, cleaner car, lorry and bus engines become more common, pollution levels should decline, wiping out any increase from a bigger Heathrow.

Sensor network

Prof Jones said using lots of smaller sensors, dotted in hard to reach places, gave them a clearer picture of what was going on.

“By deploying a network of sensors we can tell directly from the measurements, what’s been emitted locally from Heathrow airport and what’s been blown in, mostly from central London. That’s the real strength of the sensor network,” he said.

“The major result from this study is that we have tested the models far more critically than you can from a single measurement site.”

Currently, the air has climbed above European health limits at several sites near Heathrow. This work suggests that as cleaner engines kick in levels will fall again.

It is a conclusion that tallies broadly with previous research for the government, but that research relied on estimates, whereas this latest work used more accurate, real-world measurements.

Graphic showing the proposed Heathrow expansion.

Opponents think air quality is the Achilles heel for Heathrow expansion and could be where it is challenged in the courts. That is what happened the last time they wanted to build a third runway.

[….. more general stuff  on May etc ….. ]

This latest, million-pound research was funded by the Natural Environment Research Council (NERC) and alongside Cambridge, experts from the universities of Manchester and Hertfordshire, Imperial College London, CERC Limited and the National Physics lab where involved.

Heathrow helped them put the sensors up and British Airways provided some flight data, but neither handed over any money or were involved in the actual work.

Government silence

Last December, the government told the BBC it had to go away and double-check a few things before making a decision, claiming it was “subject to further consideration on environmental impacts and the best possible mitigation measures”.

I have asked, but they won’t tell me what they’ve been checking for nigh on a year. And I’m not the only one.


….. and there is more on other topics ….  and this version was slightly updated later in the day.


NERC funding:

NERC say “We are supported mainly by the Department for Business, Energy & Industrial Strategy (BEIS)”.  Its CEO is Professor Duncan Wingham.


See also:

New research on Heathrow air pollution not convincing

6 October 2016  (Client Earth)

Reports on new research have today suggested that Heathrow airport could build a new runway without breaking European pollution laws.

Reacting to the report ClientEarth CEO James Thornton said:

“When making the decision on Heathrow the government has a moral and legal duty to protect people’s health and ensure they have the right to breathe clean air.

“It shouldn’t base its decision on optimistic modelling at best and a naive view of the car industry that has proven time and time again it can’t be trusted to bring levels of air pollution down.

Heathrow air pollution must be cut drastically

“The government’s own report recently showed that diesel cars are emitting on average six times the legal limits when tested on the roads. They have even admitted one of the reasons we have toxic air is because car makers have failed to meet legal emissions limits.”

“Last year the UK Supreme Court ordered the government to draw up new plans that would bring air pollution in London within legal limits as soon as possible.

“Even without expansion, the area around Heathrow will continue to be in breach of legal pollution limits until 2025. Air pollution around the airport needs to be cut drastically before we can think about expansion.”

See earlier:


Updated air quality plan insufficient to address Heathrow challenge

Air pollution around Heathrow has been in breach of legal limits for many years and could prove a significant barrier to expansion. At the time of the Airports Commission’s recommendation this summer, the Government’s modelling indicated that breaches of the NO2 limit in London would continue until and perhaps beyond 2030. Under the Airports Commission’s plan a new runway could be operational by 2025, and would be likely to further worsen air quality in the Heathrow area.

Defra has, however, now published an updated air quality ‘plan’, drawn up in response to the Supreme Court ruling in April that the Government’s strategy would fail to achieve EU legal limits in the ‘shortest time possible’ and must be improved. Under the revised plan, NO2 would be within legal limits by 2025 throughout London.

But the difference compared with the earlier plan appears to relate almost entirely to new, more optimistic assumptions being made about emissions from diesel vehicles rather than to any new policies or strategies at a national level. The only significant new proposal relates to the formation by local authorities of Clean Air Zones, similar to the London Ultra Low Emission Zone, in which access to the most polluting vehicles could be restricted.

AEF considers both that the plan fails to demonstrate convincingly that the UK is taking sufficient action to meet legal limits, and that they will in any case need to be redrawn to take account of the emissions associated with Heathrow expansion, should Government give the project a green light. A decision on this is expected by the end of the year. We recently signed a joint letter to the Government about Heathrow expansion and air pollution.

We have submitted comments (some by way of the online form and some, given the limitations of this format, directly to the Environment Minister) arguing that Defra should:

  • Set out in detail why its previous forecasts for emissions from diesel vans were wrong and what gives it confidence that the new, much more optimistic, figures are accurate
  • Commit to redrawing the air quality plan to take account of the impact of Heathrow expansion should the Government give the project its approval.
  • Make clear that planning consent should not be granted to a project (a) that will worsen air quality in an area where breaches to either current or likely future air quality limits are already anticipated or (b) where there is a significant risk of it causing breaches to either current or likely future limits.

Download: AEF comments on Defra’s “consultation on draft plans to improve air quality: tackling nitrogen dioxide in our towns and cities” 



AEF said: 

From “Comments from the Aviation Environment Federation on Defra’s “consultation on draft plans to improve air quality: tackling nitrogen dioxide in our towns and cities”, September 2015


The relevance of this work for potential expansion at Heathrow

Our interest as an organisation is limited to the environmental effects of aviation, which includes the air pollution associated with both aircraft and airports (including surface access for both people and freight).

While emissions even at lower levels than those currently legislated for by the EU can harm health, and we support measures to improve air quality around all UK airports, it is only on the roads around Heathrow that emissions are known to consistently breach legal limits.

The Government is nevertheless currently considering whether or not to accept the advice of the Airports Commission (AC) to expand the airport – a development that would, the AC admits, worsen air quality compared with baseline forecasts.

At the time of the AC’s final publication, such breaches were anticipated to continue beyond the opening date of a new runway, with emissions very significantly over the annual mean NO2 limit of 40μg/m3 .

The unmitigated forecast for 2030 at Bath Road is, based on Defra modelling, 47.4 µg/m3 without expansion or 48.7 µg/m3 if a North West runway was to be built1 . (Table 9.4, Airports Commission Final Report, July 2015 )

An effective package of mitigation measures beyond those currently anticipated, the Commission says, could collectively reduce NO2 by 2.4 to 3.6 µg/m3 .

But this would clearly still leave the Bath Road site significantly in breach of the legal limit. The new figures published with the Defra consultation closing today now anticipate emissions being below 40 µg/m3 at all receptor sites by 2025 – a very marked difference from the previous estimate.

Our concerns about this in relation to the possibility of an expansion of Heathrow airport are follows.

1. We cannot, for the reasons set out above, feel confident in the re-forecast of emissions from diesel vans (which are responsible for a significant proportion of emissions around Heathrow), that are now expected to bring about this dramatic improvement, without further evidence. Our concern is compounded by the fact that significant improvements in air quality around Heathrow have been forecast in the past, and have failed to materialise.

Defra should, in our view, to set out in detail

(i) why its previous forecasts were so significantly wrong

(ii) what now gives it confidence in the new forecasts, and

(iii) what policy measures, such as appropriate planning controls, will be put in place if the new forecasts turn out to be optimistic.


2. The work presented by Defra for consultation does not include modelling of the impact of a third Heathrow runway on NO2 levels. Even if the new forecasts prove correct and emissions at Bath Road are below 40µg/m3 by 2025, a year before a new runway could be operational the AC estimates, it is clearly very possible that a new Heathrow runway could push them back over the limit. Should the Government announce in December  [it did not] that it supports Heathrow expansion, we suggest that this plan and consultation will need to be redrawn to consider the impact of that decision, modelling emissions associated with construction and use of the runway and any associated increase in road traffic. The modelling will need to extend beyond 2030, as the runway is predicted to be operating below its maximum capacity at that point. [so air pollution levels are likely to get worse as the use of the runway increases].

3. The Airports Commission has argued that the new runway should go ahead even if emissions remain in breach of health-based legal limits and even if expansion would compound the problem, as long as there is at least one other site in London where air quality is worse still, such that the Heathrow project did not strictly ‘delay compliance’. It cites advice from the Highways Agency as following a similar approach in relation to road building. This suggests a potential approach whereby instead of regarding the limit values as an absolute requirement across all areas of a zone, planning decisions could be taken on the basis of a cynical reading of the EU law that allows an increase in harm to public health. The legality of this approach has meanwhile been challenged by Robert McCracken QC in advice to Clean Air in London 2 ( ).

We very much hope that Defra will make clear that planning consent should not be granted to a project (a) that will worsen air quality in an area where breaches to either current or likely future air quality limits are already anticipated or (b) where there is a significant risk of it causing breaches to either current or likely future limits.


AEF also said:

Are Heathrow’s concessions enough to address the impacts of a third runway?

In this article, we look at the key commitments, reflecting what impact they would have on the environmental impacts of a third runway, which the Airports Commission described as ranging from adverse to significantly adverse. We highlighted in our blog following the Airports Commission’s final report that many of the proposed concessions failed to adequately deal with the environmental challenges of a new runway.

[Only the section on air pollution is copied here …] 


Air quality

  • Airports Commission recommendation: Additional operations at an expanded Heathrow must be contingent on acceptable performance on air quality. New capacity will be released when it is clear that air quality at sites around the airport will not delay compliance with EU limits.
  • Heathrow: Agree to this recommendation and state that the airport is taking further steps through an ultra-low emissions zone for airport vehicles, developing plans for an emissions charging scheme, and support the Environment Agency scrutinising their plans

AEF has argued that the Airports Commission’s recommendation that expansion should not be allowed to “delay compliance” with the legislation was as a result of an inability to demonstrate that the Heathrow area – which has exceeded air quality limits for many years – could in fact be brought into compliance with legal air quality law if a third runway was built.

Rather than accepting the condition proposed by the Airports Commission, AEF believes permission for a new runway should only be given if it can be proven that this is compatible with bringing air pollution in the Heathrow area within legal limits. The issue of whether other locations in London are forecast to breach legal limits should not be used as an excuse for failing to bring the Heathrow area into compliance with the law.


… full AEF statement here