EU cities with highest annual mean NO2 levels (μg/m3)
40 μg/m3 is the level considered safe for human health by the EU
But Pencharz said that the data cited was not representative, because other cities have fewer monitoring stations and submit less data. London had more monitoring stations than Paris or Rome, for instance, with 157 sites compared to 32 in Paris, 13 in Rome, 17 in Berlin and 19 in Amsterdam, in 2011. He also said other cities frequently sited their monitoring stations away from some of their main polluting sites, and therefore were not as reliable as the UK.
The mayor’s office said: “More monitoring stations means we can do the responsible thing and place our monitoring stations directly in the most polluted roads. Some cities place their monitoring stations in vast green parks or traffic-free courtyards, hence the lower figures they report. That’s why Oxford Street records comparatively high levels of pollution than for many other cities – but to say it is the worst of any place on Earth is misleading.”
Martin Adams of the European Environment Agency confirmed that member states could pick the data they wanted to submit on air quality, provided that it met certain criteria and a minimum number of sampling stations were included. “That is the flexibility that member states have,” he told the Guardian. “That is the responsibility of member states – to choose the monitoring stations [from which they submit data].”
Pencharz also said London was leading the world’s cities in improving air quality. He has said that emissions of NOx have fallen on average by a fifth since Johnson was elected, and the number of Londoners living in areas that break EU limits for the gas had been halved.
NO2 can contribute to breathing difficulties, and is a particular problem for young children, older people and susceptible adults, such as those with existing respiratory conditions. Diesel-fuelled vehicles are a major source of the pollutant, and London is facing hefty fines from the European Union for flouting NO2 limits.
Johnson unveiled plans on Tuesday to double the current congestion charge for drivers of diesel-powered vehicles. He said that diesel was worse for air pollution than alternatives including petrol, electric vehicles and other transport. The new plans – which must be put out to consultation before they can be adopted – would not come into force until 2020.