Will Health Effects from emissions from Heathrow Expansion be felt just within 2 kilometres?

The Airports Commission had as its study area, for the effects of Heathrow expansion, an area of just 2 kilometres from the boundary of the expanded airport. Chris Grayling wrote to the chair person of the Transport Committee on the 23rd February 2018 saying that:

“The DfT’s approach assessed the health impacts on populations living within 2km of the expanded airport using updated relationships between pollutant concentrations and mortality, published by DEFRA …………..The study area, which captures over 98% of additional emissions that could occur from expansion, was determined by the Airports Commission’s consultants to include those locations where expansion was expected to make a significant contribution to ambient pollution levels”

Is this figure of 98% emissions capture within 2 km of the boundary true or false?

Well; the London Assembly have collated a lot of air quality data, which has been in the public domain for some years. King’s College London have been instrumental in collating much air quality data. The data is available by Borough and as an “apportionment tool” to tell us the relevant sources (including aviation) of pollution at any spot in the greater London area. The website is at


Go into Richmond Old Deer Park and you might think that the majority of NOx there is from nasty smelly diesel lorries roaring down the A316 to the M3. You would be wrong. According to the Data Apportionment Tool, no less than 77.7% of NOx in Richmond Old Deer Park by the side of the A316 comes from aviation. So; let’s go a bit further away from Heathrow and see what happens:

Let us go to Kew / North Sheen, 11km from touch-down and look forward to 2020:

Put the co-ordinates into the tool and:

We are shown that 57.7% of NOx comes from aviation. There is a pie chart too:

The legal limit is an annual mean of 40 micrograms per cubic metre. There is a NOx map:

and a map of NO2 only

which show that in 2020 there will be areas particularly close to the roads that will breach the legal limits. That is with two runways at Heathrow and 57% of the NOx coming from aviation.


Let us go further away to Putney, which is under the flight path but is over 15 kilometres from touch-down at Heathrow:

Put in the co-ordinates to the calculation tool and:


We find that aviation is still contributing to 33% of the NOx emissions. Putney is worse off than Kew though because total emissions are greater and therefore the breaches are more severe. The total emissions, of which aviation contributes 33%, is bigger. The NO2 map is:

and the NOx map is:


Heathrow itself is way over the permitted limits and is predicted to be so in 2020 and 2030.

The 2020 map:

and the 2030 map is only a little better:

And all that is just from two runways!

Aviation apportionment readings stretch back to Clapham Junction and beyond

So Mr Grayling: why are you telling us and the Transport Committee that 98% of emissions from an expanded Heathrow would be captured within 2 kilometres of the airport boundary?

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  1. Charles Mitchell
    17th October 2018

    I am convinced that if any airport expansion is warranted, which is probably doubtful given the latest greenhouse gas/temperature rise warnings, it should be at Gatwick.

  2. Gerald Morgan
    17th October 2018

    Brilliant. Many thynks

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