CEH's Professor Mark Sutton was recently invited to provide evidence to Parliament on the impacts of air pollution. Defra is consulting on how the UK can meet European Union requirements for limiting emissions of nitrogen dioxide.

The Environment, Food and Rural Affairs Committee asked Mark Sutton, as well as Professor Paul Wilkinson, London School of Hygiene & Tropical Medicine, and Professor Martin Williams, London School of Hygiene and Tropical Medicine, to act as expert witnesses in a committee session on 9 December 2015.

This is the recording of the evidence session.

Further information

Transcript of the oral evidence session

Written evidence from Mark Sutton provided to the EFRA Committee in advance of the oral evidence session.

Defra's responsibilities for air quality inquiry


Key excerpts from Mark Sutton's oral evidence:

'On the ecosystems aspect... if we express it in terms of the area of the United Kingdom where ecosystems are at threat of nitrogen deposition, it is 62% of the area. 89% of the special areas of conservation have exceedance over part of their area. That is the scale of the area threat to our ecosystems. In terms of the changes, we have loss of biodiversity, flowering plants going out, algae coming in and colonising, green, gloopy slime on trees—lots of changes.'

'It is worth adding that, in terms of those legal limits linked to human health effects and air pollutants, we do not really have that with the ecosystems side.'

'Essentially, the emissions are as gases, be they NOx from a car or ammonia from a cow... In the case of the hotspots on agriculture and ammonia, it is the livestock rather than the cropping. The fertilisers emit some, but it is only about 20%. It is 80% from the pigs, the poultry, the cattle. Once it gets up into the atmosphere, it slowly mixes and the different compounds form the particles... Others in Europe are getting our pollution; we are getting theirs.'

'In terms of effects, it is fair to say that the biggest ecosystem effects you see out there are more from the farms in the hotspots than they are from the roads. One reason for that is simply that the roads are a big long line source and better distributed than the farm, which is often a point source. The other thing is that the ammonia can reach the ground more quickly; it is more soluble. Just because of those physical issues, the ammonia ends up having a bigger impact.'

'Coming on to the ozone, we have the nitrogen oxides reacting with volatile organic compounds, some of which are from combustion sources, some of which are natural, producing the ozone. That is primarily rated as a crop problem. It is a problem for agriculture, because it means the crops are growing less, producing less yield.'

'As I said in my evidence, one thing is to think of it as not just a problem for agriculture, but an opportunity for agriculture. I put in there some of those fertiliser values. Across Europe, €18 billion worth of nitrogen pollution goes up into the atmosphere per year. That is the fertiliser value, as compared to the common agricultural policy: let us say €55 billion. This is real stuff that is useful to keep in the farming system. If the farming part of that was €12 million, that is 25% of the CAP going up in smoke off the farm—bad for the environment, bad for the farmer. There really are opportunities there, and there are measures, which we might talk further on, that a farmer can do, where it will be profitable for him to take action.'

'One thing that is developing is this whole nutrient recycling and reuse market. I was recently in the Po valley, where they are doing this. They are doing it in Brittany as well. Someone will take your manure at a small price; they will de-gas the ammonia and put it together with sulphuric acid to make ammonium sulphate—fresh fertiliser. They will get biogas at the same time. Then you have your processed manure back with a lower nitrogen to go into the field. It is driving an economic market with opportunities.'

'In the world, $40 billion a year worth of NOx is going up into the atmosphere as fertiliser value.'



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