Emission trends of ammonia NH3

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EEA-32 ammonia emissions have decreased by 20% between 1990 and 2005. The agricultural sector remains the major source of ammonia emissions (93% of total 2005 emissions).

These emissions derive mainly from the decomposition of urea in animal wastes and uric acid in poultry wastes. Emissions depend on the animal species, age, weight, diet, housing systems, waste management and storage techniques. The majority of the reduction in emissions is due to the combination of reduced livestock numbers across Europe (especially cattle), and the lower use of nitrogenous fertilisers. Emissions from road transport, although relatively small have been rising as a result of the increasing use of three-way catalytic converters in the vehicle fleet (this is due to an unwanted reaction involving hydrogen which reduces NO to NH₃.

However, emissions are projected to fall in the future as the second generation of catalysts (which emit lower levels of NH₃ than the first generation catalysts) penetrate the vehicle fleet.

NH₃ emissions have also declined in countries outside the European Union (EFTA-4 and CC-3) between 1990 and 2005. Again this is primarily due to reductions which have occurred in the agricultural sector as a result of decreasing animal numbers.