This post is by Professor Martin Williams of the Environmental Research Group at King’s College London. He was previously chairman of the Executive Body of the UNECE Convention on Long Range Transboundary Air Pollution.
At this time of year it’s customary to present awards for achievements over the previous year. If there was an award for Air Pollutant of the Year then nitrogen dioxide would surely win.
Nitrogen dioxide (NO2) has hit the headlines on several fronts. The government is facing possible infraction proceedings from the European Commission and, following action by Client Earth, is under an obligation from the UK’s Supreme Court to produce a plan for achieving the EU limits on NO2 in the shortest possible time.
The UK’s advisory body on the health effects of air pollutants (COMEAP), has followed up the World Health Organisation’s conclusion that there is evidence for large effects of NO2 on health, independent of the impact of PM2.5 particles. Before Christmas, COMEAP promised there would be a full report in the New Year on its analyses of the published data but, in the interim, it has confirmed there’s a risk.
No drop in diesel emissions over 20 years
The VW scandal has also been primarily about NOx and NO2, and the revelations have shed light on why there has been little reduction in real world emissions from diesel vehicles over the past 20 years or so.
Defra’s consultation on the government’s plan for NO2 concentrates, understandably, on a relatively narrow aspect of air quality policy: achieving legal compliance for this one pollutant in a narrow range of mostly roadside locations. While a national framework for Clean Air Zones is welcome, it’s not yet clear how Defra will enforce the plan. The implementation of Clean Air Zones is left to the local authorities, with no obvious sanction if they decline to impose them, do it too late or make them weaker than needed to achieve compliance.
Compliance by 2020 looks challenging
There is also some doubt over whether Clean Air Zones will be sufficient to turn the UK’s vehicle fleet round in time to achieve compliance by the dates Defra suggest. Compliance by 2020 in areas other than London is challenging, requiring the full implementation of Clean Air Zones and a turnover of the vehicle fleet within four years.
For London, the timeframe of projected compliance by 2025 – which is only nine years away – also looks challenging. These doubts arise not least from the fact that modelling behaviour change and purchasing decisions, on which the plan is predicated, is difficult and appears to be based on expert judgement (see table 6.7 of the Draft Evidence Annex of the Defra Consultation). Monitoring progress is essential, both in terms of policy implementation and understanding concentrations of NO2.
Focus is too limited to improve health
Although achieving the limit values for NO2 will result in some public health benefits, the current plan is too narrowly focused on relatively small areas in just a few cities to provide the optimum benefits to health. A more comprehensive strategy for air quality across the whole of the UK is needed, to provide the maximum feasible benefits to human health.
Legal limits do not represent ‘safe’ levels below which no adverse effects occur and so strategies should be considered which go further. These should take a holistic view of transport and its impact on air quality and health, going beyond the establishment of Clean Air Zones, and looking more widely across all government departments at how to promote cleaner options for vehicle purchasing and use, and encourage more journeys by walking, cycling and public transport. Urban planning schemes, such as pedestrianisation, could also play an important role in improving air quality.
A broader, longer term strategy should also encompass policies to meet the Climate Change Act target of 80 per cent reduction on CO2 equivalents by 2050. Achieving this in concert with optimal air quality policies would deliver the biggest improvement in public health impacts from air pollution since the 1956 Clean Air Act.