Research by campaigners has found an improvement of over 40% in local air quality around Heathrow Airport in the three months to the end of May 2020, compared with the same period in 2019.

Using data from Air Quality England, Stop Heathrow Expansion has found that five air quality monitors around Heathrow which breached the maximum legal limit in March–May 2019 have shown an average 41% improvement in the same period in 2020 while the country was in lockdown.

UK air quality laws state that nitrogen dioxide concentrations must not average 40 micrograms of NO2 per cubic metre per year.

Of the sites highlighted in Table 1, the three Hillingdon sites breached legal limits from, January–December 2019. The sites in Slough and Hounslow recorded breaches throughout the year, with as 45.7 MG recorded at the Hounslow monitor in April 2019.

The lockdown has ensured readings of one monitor, located on Heathrow’s Northern Perimeter Road, show a whopping 50% improvement in local air quality. Another site located outside Cherry Lane Primary School, close to the M4 motorway, saw a 46% reduction in nitrogen dioxide emissions, from 44.1 MG in March–May 2019 to a safer 23.9 MG in the same period in 2020.

Tim Johnson, Director of Aviation Environmental Federation, said: “During lockdown, communities around airports and under flight paths have come to appreciate the extent to which their lives were impacted negatively by aircraft noise and emissions before the pandemic.

“They will not want to lose the relative tranquility and clean air that have characterised the last three months, and they, together with environmental organisations, are calling on Government to ensure a green recovery that protects many of these benefits.”

A monitor within the Slough borough, on a key road linking Heathrow to Slough, saw a 35% increase in local air quality – from an illegal reading of 41.2 MG in 2019 to 27.2 MG in 2020. 

Similarly, a monitor on the A4 within Hounslow saw a 36% reduction in nitrogen dioxide, from an average of 39.6 in 2019 – with individual months such as March and April 2019 showing concentrations of 40.0 and 45.7 MG respectively – to just 25.4 in March – May 2020.

Geraldine Nicholson, from Campaign Group Stop Heathrow Expansion, said: “Heathrow expansion would lead to a huge detriment of local air quality. As we have seen during lockdown, local air quality around Heathrow has improved with the lack of planes and associated road traffic. 

“We have to ensure that our air quality is not allowed to return to previously unsafe levels. A major step to achieving that would be for Heathrow to scrap its expansion plans and focus on maintaining this improvement in local air quality once operations increase at and around the airport.”

This substantial improvement in local air quality around Heathrow is due to the reduced airport operations and a 97% reduction in passenger traffic.  This is due to reduced number of planes damaging the local atmosphere. Substantially reduced the number of private car journeys. Reduced the number of cargo-related HGV movements on the local road network.

Stop Heathrow expansion is calling for Government to adopt the World Health Organisation guidelines on nitrogen dioxide limits.

Table 1 - Pollution Data Comparison ’19-20


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