Cut agricultural ammonia emissions

The additional cost for farmers to reduce ammonia emissions is only a small percentage of the total volume of subsidies that flow to the agricultural sector through the Common Agricultural Policy.

According to the European Environment Agency (EEA), excessive levels of fine particulate matter (PM) are responsible for 431,000 premature deaths every year in the EU. The key legislation for reducing PM levels in Europe is the EU National Emission Ceilings (NEC) directive, which covers not only emissions of primary, directly emitted PM, but also emissions of PM precursor gases, including ammonia, sulphur dioxide, and nitrogen oxides, which react in the atmosphere to form tiny particles of ammonium sulphate and ammonium nitrate.

In a recent article in the Lancet, a group of European health and nitrogen scientists points out that these secondary inorganic aerosols (SIA) can make up as much as 50 per cent of the total fine particle concentration in the air, and that the contribution of ammonia emissions often represents 10–20 per cent of PM levels in densely populated areas in Europe. In areas with intensive livestock farming, this share is even higher. Moreover, ammonia speeds up atmospheric reactions of primary sulphur dioxide and nitrogen oxide emissions, which results in larger concentrations of total SIA.

But what are the health effects of these secondary particles, and which precursor emissions are most important?

According to the authors, twenty years of research has not shown that any single particle components contribute more to health risks than others, which means that health benefits can be expected from all efforts to reduce PM concentrations in the air.

The proposal for a new NEC directive includes targets for future reductions in emissions of all three SIA precursors, but at very different percentages. From the base year 2005 up to the first target year of 2020, total EU emissions of sulphur and nitrogen oxides should be reduced by 59 and 42 per cent respectively, while those of ammonia should be cut by only 6 per cent.

Larger reductions are proposed for 2025 and 2030, but the disparity between sulphur and nitrogen oxides on the one hand and ammonia on the other hand remains. It is pointed out that this is hard to defend scientifically, because to achieve the needed reduction in PM concentrations all precursor gases need to be cut. More importantly, abatement of ammonia is a key factor for abating SIA because ammonia reductions contribute more to lowering PM concentrations than do reductions of sulphur and nitrogen oxides.

More than 90 per cent of the total ammonia emissions in the EU originate from farming, especially livestock farming. The social cost of all nitrogen pollution in the EU member states has been estimated at €75–485 billion per year, of which close to half is attributed to health damage from SIA air pollution.

Abatement measures come at a cost, but the total cost for agriculture of the proposed emission controls in 2030 is a mere 2–3 per cent of the total air pollution emission control costs in the EU in that year (about €2.5 billion per year out of €92 billion per year).

This cost is also a small percentage of the total volume of subsidies of about €60 billion that flow from the EU budget to the agricultural sector through the Common Agricultural Policy.

It is concluded that in view of the contribution of agriculture to PM concentrations, the health damage caused by air pollution from agriculture is estimated to be far greater than is the burden placed on this sector by the current proposal for a new NEC directive.

Moreover, as the EU starts to promote the circular economy, there is a strong case to reduce ammonia emissions as part of innovation to increase economy-wide nitrogen use efficiency. And, according to the authors, there is a major business opportunity in improving emission reduction and recycling technologies that further strengthen the case for revision of the NEC directive.

Christer Ågren
Source: Article by Bert Brunekreef, Roy Harrison, Nino Künzli, Xavier Querol, Mark Sutton, Dick Heederik, Torben Sigsgaard in the Lancet Respiratory Medicine, published online 8 October 2015.

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