January 14, 2019

expert reaction to Defra’s clean air strategy

Reactions to Defra’s clean air strategy which sets out plans to manage sources of air pollution.

Prof Mark Sutton, Environmental Physicist at the Centre for Ecology and Hydrology (CEH), said:

“This is the most significant document on controlling ammonia emissions that UK government has ever produced.  It proposes a suite of regulations, permitting and financial support mechanisms, which, if adopted, would substantially reduce UK ammonia emissions with major expected benefits for both vulnerable ecosystems and human health.

“For the last 25 Years, it has often felt like ammonia was the forgotten pollutant, the Cinderella of UK air pollution policy.  The 2019 Air Quality Strategy indicates that this is about to change, as Defra now grasps the ammonia challenge.  Yet there is still much to do.  In order for the ambition to survive parliamentary and wider debate, and to actually enter legislation, CEH and other research organisations will need to continue providing underpinning scientific evidence to support the process.

“The proposals for ammonia already draw strongly on the analyses provided by CEH and our partners in the UNECE Geneva Air Convention.  As one of the co-chairs of the UNECE ‘Task Force on Reactive Nitrogen’, I am really pleased to see that the multi-actor consensus we have developed over the last 10 years on measures to reduce ammonia emissions is strongly reflected in the Air Quality Strategy.

“Concerning low-emission technologies, the Number-One method agreed by the UNECE Task Force on Reactive Nitrogen is low-emission manure spreading, which countries like the Netherlands, Belgium and Denmark have already shown to be central in reducing ammonia emissions.  In the case of liquid manures or ‘slurry’ – a mixture of urine and animal faeces – this is likely to mean an effective prohibition of the old ‘splash plate’ method, where slurry is spread all over the field surface.  Instead of retaining this 1950s technology, the Air Quality Strategy will foster innovation through a range of more precise slurry spreading methods, as recommended by the UNECE.  These typically apply slurry in narrow, evenly-spaced bands or inject it into the soil.  Such low-emission methods will also be required for the liquid ‘digestate’ that remains after anaerobic digestion, where there is further potential to develop innovation in more ambitious nutrient recovery methods.

“There is one caveat that should not be forgotten.  As Mr Gove recognises in his Foreword to the Air Quality Strategy, ‘ammonia emissions from agriculture are also increasing’.  This relates especially to increasing cattle population following the 2015 ending of EU milk quotas, to increasing urea fertilizer usage and to increasing poultry numbers.  The proposed commitment to require low-emission approaches for urea is therefore highly relevant, while Defra will also need to ensure that possible future increases in livestock numbers do not cancel out the benefits of adopting low-emission technologies.”

Prof Ian Colbeck, Professor of Environmental Science, University of Essex, said:

“It’s encouraging to see the Government recognising the importance of PM2.5 and aspring to meet the WHO guidelines.  It’s not clear how the Government plans to achieve them and it looks like we’ll have to wait for another report.  However air pollution doesn’t recognise international boundaries so legislation in Europe will also be required.  Britain can’t do this alone.”

Dr Maria Neira, Director for Public Health and the Environment at WHO, said:

“The United Kingdom’s Clean Air Strategy inaugurates the race for a cleaner environment – a competition in which health is a primary winner.  WHO applauds the United Kingdom’s determination to enact major changes that will protect people’s health and the environment.

“The reduction of the 7 million premature deaths annually associated to air pollution must fuel our ambition for similar Clean Air Strategies across the world.”

Prof Alastair Lewis, Professor of Atmospheric Chemistry, National Centre for Atmospheric Science, University of York, said:

“The wide range of simultaneous actions being proposed, and sectors and pollutants being targeted, is a reflection that further improving air quality in the U.K. is getting harder and harder, now the big industrial and combustion sources are under control.

“Whilst road transport emissions remain a critical source of pollution in U.K. cities they are on a gradual downwards trajectory for both NOx and PM.  The rate of adoption of electric vehicles may be proceeding only slowly, and uncertainty remains over their non-exhaust emissions, however the national strategy for reducing road transport emissions is likely to be ultimately effective, if a somewhat lengthy and drawn out process over two decades.

“Whilst road transport has already seen recent reductions in emissions, domestic and agricultural releases of air pollution stand apart and have quietly been increasing in recent years.  Greater use of fertilisers, popularity of wood burners, and the use of solvents in the home now make up a substantial fraction of national emissions, although they have received far less publicity.  We don’t yet think of our homes or food as a source of air pollution in the same way we do our cars, but we should do.

“The emphasis placed on reducing ammonia and volatile organic compounds reflects the multiple benefits that would likely accrue if emissions declined.  Less ammonia and NMVOC (Non-Methane Volatile Organic Compounds) would mean less PM2.5 and ozone being formed outdoors, less damage to plants and crops, and would lead to lower personal exposures to pollution indoors as well.

“The adoption of the WHO targets as an aspiration is highly laudable, and sets the U.K. apart in the scale of its ambition.  The full evidence on reductions needed to attain the tougher WHO 10 microgram/m3 guidelines for PM2.5 is to be published later, but one would anticipate that there are likely to be some urban areas of the U.K. where this could be close to impossible to achieve.  Explaining to those living in the centre of our biggest cities that perhaps the target will never be met where they live will be a unenviable job.  Even in a fully electrified future, a city centre combination of PM from transport friction, from dust, from construction, from cooking, and even from natural sources may, in combination bust the limit.”

‘Clean air strategy 2019’ was published by Defra at 00:01 UK time on Monday 14 January 2019, which is also when the embargo will lift.  

Declared interests

Prof Ian Colbeck: “None.”

Prof Alastair Lewis: “No specific interests to declare.  I am a member of AQEG, Defra’s scientific expert group but I don’t see that as a conflict.”

None others received.