Pollutant Information: Nitrous Oxide 

About Nitrous Oxide

Category: Greenhouse gases

Nitrous oxide (N2O) contributes to climate change due to its positive radiative forcing effect and the gas has a relatively high impact, with a global warming potential (GWP) of 298 compared with a figure of 1 for carbon dioxide. The agriculture sector dominates emissions of N2O: emissions from agricultural soils in 2014 account for 64% of total UK emissions, and other agricultural sources add another 7%. Other important sources in 2013 include road transport and power generation. Historically, industrial processes have been a significant source, due to emissions from the manufacture of chemicals – nitric acid and, in particular, adipic acid. In 1998 the sole UK manufacturer of adipic acid commissioned an abatement unit, leading to the significant reduction in the contribution to total emissions from that plant. That process subsequently closed in 2009. The contribution of road transport to total N2O emissions is small, but there was an overall increase in N2O emissions between 1990 and 1999 from this source. This was due to the introduction of catalytic converters, since N2O was formed as an unwanted by-product in reducing NOx, in particular by the early generation of cars with catalytic converters. Total emission levels have fallen by 55% since 1990.

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Time series graph


Notable events

Start year End year Sector Information Impact
2000 2011 Agriculture - Soils Decrease in synthetic fertiliser application to soils for crop growth. The EU Nitrates directive/NVZs put restrictions on the use of nitrates. Decrease in emissions
1991 1993 Industrial Processes Industrial nitric and adipic acid plant closures. Decrease in emissions
1998 1998 Industrial Processes Abatement installed at the adipic acid plant to comply with IPPC regulations. Decrease in emissions