Pollutant Information: Ammonia
Category: Air pollutants
Ammonia (NH3) plays an important role in a number of different environmental issues including acidification, nitrification, and eutrophication. It also acts as a precursor to secondary particulate matter, therefore contributing to the related health impacts. The atmospheric chemistry of NH3 means that it can react with other chemicals to produce particles, which can be removed from the atmosphere by rain, or to produce other ammonia compounds, which can be transported long distances. As a result, NH3 emissions can impact on a highly localised level, as well as contributing to effects from long-range pollutant transport. Agriculture is the dominant source of emissions, with the sector accounting for 87% of total emissions in 2021. Emissions occur due to the use of nitrogen-based fertilizers and from livestock farming, and more than half of the agricultural sector emissions are related to cattle. Total UK emissions in 2021 were 13% lower than in 1990, and 5% lower than in 2005. The most significant causes of reductions between 1990 and 2005 were decreases in pig numbers, decreased use of nitrogen fertilizers, and the banning of crop residue burning. The lack of a reduction in overall NH3 emissions since 2005 is largely because of a reversal in the previous downward trend in emissions from fertilizer use, increasing emissions from dairy cattle, and growth in the spreading on agricultural land of digestates from anaerobic digestion of non-manure wastes. The growth in emissions from these sources has offset reductions that have occurred from road transport and from beef farming due to decreasing cattle numbers. The reduction in emissions from road transport is due to the fleet penetration of more modern petrol cars with improved catalytic converters compared with older cars, this more than offsetting a slight increase in emissions from diesel vehicles. A reduction in emissions of 11% from 2021 will be required for the UK to meet the National Emission Ceilings Directive and Gothenburg Protocol target for 2030.
Time series graph
|Direct Soil Emissions
|Increase in NH3 in recent years. Emissions closely linked to total N use and, more importantly the proportion of N applied as urea (which has a much higher NH3 EF). NH3 emmissons are also driven by the price of fertiliserz with 1997 being the lowest price year. The EU Nitrates directive/NVZs put restrictions on the use of nitrates.
|Decrease in emissions
|Direct soils emissions
|Introduction of large scale use of non-manure-based digestate spreading
|Increase in emissions
|Widespread increase in anaerobic digestion to make use of waste products and generate biogases to use as fuels, some of which is injected into the national natural gas network.
|Increase in emissions