Defra will focus on ‘nitrogen dioxide thresholds’

Rory Stewart tells Parliament that government measures will seek to reduce ambient NO2 rates below 40 micrograms per cubic metre

The potential air pollution impact of a mooted third runway at Heathrow is a “totally separate question” to the government’s current focus on nitrogen dioxide thresholds, according to the UK’s air quality minister.

Speaking in Parliament last week (March 17), Defra minister Rory Stewart outlined his Department’s objective to focus on ‘nitrogen dioxide thresholds’ in the battle to bring the UK’s air pollution problem in line with UK targets.

Rory Stewart, Defra's minister for air quality

Rory Stewart, Defra’s minister for air quality

The minister was asked by the Labour MP for Brentford and Isleworth Ruth Cadbury what the government would do to achieve legally binding targets for air pollution in the event that a third runway is built at Heathrow Airport.

The UK is currently one of several EU Member States in line for potential infraction proceedings due to its failure to meet air quality since 2010.


The government submitted a revised plan in December which outlined the government’s proposals to meet the air quality targets, including measures to introduce clean air zones in five cities.

Responding to the question on the impact of a new runway at Heathrow on air pollution, Mr Stewart said: “The current objective is to focus on nitrogen dioxide thresholds and ensure that we reduce ambient air quality rates below 40 micrograms per cubic metre. Heathrow is a totally separate question that must be assessed independently by the Environment Agency and our air quality monitors, to see whether ambient air quality targets are met.”

The minister was also asked why the air quality plan focussed in particular on five cities, and he added: “In those five cities, the ambient air quality level of 40 micrograms per cubic metre is due to be exceeded. Therefore, our objective is to ensure that by 2020, in Birmingham, Leeds, Nottingham, Derby and Southampton, we drop that level below 40 micrograms per cubic metre.”


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