- Last Updated on Friday, 27 July 2012 14:00
Associated topic: greenhouse effect
Emissions monitoring period: since 1990
Data source: CITEPA / SECTEN format - April 2012
Source of the pollutant
Although not traditionally included in the NOx group, nitrous oxide (N2O) is a nitrogen compound containing oxygen. Agriculture is the main source of N2O emissions, especially from nitrogenous inputs in the form of mineral fertilisers or animal manure spread on arable farmland.
A small share of N2O emissions is from road traffic, particularly from vehicles fitted with catalytic converters, and from some industrial processes such as the manufacture of adipic acid, glyoxilic acid and nitric acid.
Effect of the pollutant
N2O is used in health care as an anaesthetic. In large doses, it causes euphoria and problems with sight and hearing. It has a sedative effect and also causes vertigo, anxiety and digestive problems (nausea and vomiting). Finally, it can cause neurological problems (trembling, uncoordinated movements).
In environmental terms, nitrous oxide is a powerful greenhouse gas. It has a Global Warming Potential (GWP) of 310, i.e. 310 times the GWP of CO2, the reference greenhouse gas (GWP for CO2 = 1) (GWP values from the Intergovernmental Panel on Climate Change (IPCC)'s second assessment report published in 1995). Among the greenhouse gases covered by the Kyoto Protocol, nitrous oxide is the third largest contributor to global warming after carbon dioxide (CO2) and methane (CH4).
Classification of the sub-sectors with the highest emission levels* (excluding Land Use, Land Use Change and Forestry or LULUCF)
|Classification||Sub-sectors||Share of the sub-sector in total national emissions in mainland France (%)|
*: one sector (out of six: energy transformation, manufacturing industry, residential/tertiary, agriculture/forestry, road and other transport) is broken down into sub-sectors.
Emissions and trends (including LULUCF)
|Minimum observed:||196 kt in 2010|
|Maximum observed:||302 kt in 1997|
|Emissions in 2010:||196 kt|
Measurement unit: kt (kilotonne)
N.B.: Emissions include those from combustion and from processes.
In 2010, N2O emissions excluding LULUCF in mainland France amounted to 191 kt. Emissions from LULUCF in 2010 are estimated at 4.7 kt, or 2.5% of total emissions from all the other sectors.
All sectors of activity contribute to N2O emissions, in variable proportions. Whatever the year under consideration, the main source is agriculture/sylviculture (crops and livestock), accounting for 87% of all emissions in mainland France (excluding LULUCF). N2O emissions from the sector are from nitrogenous inputs in the form of mineral fertilisers and animal manure spread on arable farmland.
The manufacturing industry (including chemicals and waste treatment) accounted for 7% of total N2O emissions (excluding LULUCF) in 2010. These emissions are mainly from the manufacture of chemicals (especially nitric and adipic acid, accounting for 64% of emissions from this sub-sector), which produced 57% of emissions from the sector as a whole in 2010, and waste treatment (27.5%), of which 58% are from water treatment and 34% from composting.
The other sources are relatively marginal: the residential/tertiary sector (3%), road transport (2%), energy transformation (1%) and other transport modes (0.1%).
From 1990 to 2010, N2O emissions dropped by 35% (-101 kt). This decline was in the manufacturing and agriculture/sylviculture sectors. Emissions in the other sectors remained relatively stable from 1990 to 2010.
The largest drop in N2O emissions was observed in the manufacturing industry (-73 kt, i.e. -84%). This is accounted for by large reductions in certain industries, especially in the manufacture of adipic, nitric and glyoxylic acid. The manufacturing industry's share thus dropped from 30% of the French total in 1990 to 7% in 2010.
Since 1990, N2O emissions from the agriculture/sylviculture sector have been falling (-30kt, i.e. -15% from 1990 to 2010) as a result of to reductions in mineral fertiliser inputs and manure spreading (intensified dairy production). Despite this, the sector's share of total N2O emissions in France, excluding LULUCF, increased from 1990 to 2010 (67% in 1990 as against 87% in 2010). The estimated increase in 2011 is accounted for by a massive increase in fertiliser purchases at the start of the 2010-2011 campaign, in response to forecasts of high cereal prices in 2011.
N2O emissions from road transport have been on the rise since 1990 (+1.1 kt, or 38%) following the gradual introduction of catalytic converters. This is only a relative increase as road transport accounts for merely 2% of total N2O emissions in 2010. The drop observed in 2009 is accounted for by the lower sulphur content in fuel (from 50 ppm to 10 ppm). The slight rise in 2010 (0.2 kt, or +5%) is the result of an increase in traffic.