National inventory system
The National Inventory System (NIS) is a requirement of the GHG Inventory only. However, the benefits of the system apply to the AQ inventory also.
PM1.0 (Finer particulates)
Particulate matter with an aerodynamic diameter of less than 1.0 and 0.1 micrometres (µm) is referred to as PM1.0 and PM0.1 respectively. There is no requirement to report emissions of these particle sizes under the NECR or UNECE Gothenburg Protocol, but emissions are estimated as a fraction of PM10 emissions. Combustion sources of particulates are generally more significant sources of these finer particle sizes than non-combustion sources. The health effects of these particle sizes are not well-understood, but ultra-fine particles in
PM0.1 (Finer particulates)
Particulate matter with an aerodynamic diameter of less than 1.0 and 0.1 micrometres (µm) is referred to as PM1.0 and PM0.1 respectively. There is no requirement to report emissions of these particle sizes under the NECR or UNECE Gothenburg Protocol, but emissions are estimated as a fraction of PM10 emissions. Combustion sources of particulates are generally more significant sources of these finer particle sizes than non-combustion sources. The health effects of these particle sizes are not well-understood, but ultra-fine particles in
Sulphur hexafluoride
Sulphur hexafluoride (SF6) is a greenhouse gas and has a very high radiative forcing effect and a GWP of 22,800 compared with a figure of 1 for carbon dioxide. Emissions occur due to its use in a small number of applications. Annual emissions have decreased by 74% since 1995. The largest source is related to the use of SF6 for electrical insulation (83% of the total in 2022). Emissions arise during the manufacture and filling of electrical switchgear and from leakage and during maintenance throughout the equipment’s lifetime.
PFCs
Perfluorocarbons (PFCs) contribute to climate change due to their positive radiative forcing effect. Perfluorocarbons have a range of global warming potentials (GWP), which are much higher than that of carbon. However, the small quantities emitted mean that despite the high GWP values of the individual gases, the total contribution to GWP weighted greenhouse gas emissions in the UK is small.
NF3
Since the 2015 inventory submission (with emission estimates for 1990-2013), the Kyoto Protocol basket of greenhouse gases has been expanded to include nitrogen trifluoride (NF3). Total estimated emissions are very small, contributing less than 0.0001% to total UK emissions of greenhouse gases in 2022. Emissions arise from use of NF3 for electronics.
HFCs
Hydrofluorocarbons (HFCs) contribute to climate change due to their positive radiative forcing effect. Hydrofluorocarbons have a range of global warming potentials (GWP), which are much higher than that of carbon. However, the small quantities emitted mean that despite the high GWP values of the individual gases, the total contribution to GWP weighted greenhouse gas emissions in the UK is small.
PM1.0 and PM0.1 (Finer particulates)
Particulate matter with an aerodynamic diameter of less than 1.0 and 0.1 micrometres (µm) is referred to as PM1.0 and PM0.1 respectively.
PM can be emitted directly from a source (primary PM) or formed through the interaction of other pollutants (secondary PM). The National Atmospheric Emissions Inventory estimates emissions of primary PM only.
Methane
Methane contributes to climate change due to its positive radiative forcing effect, and is the second most significant greenhouse gas in the UK after CO2. The major emitting sources in recent years are enteric fermentation, landfilling of wastes, and leakage from the gas distribution system. Historically, coal extraction was also a very significant source of methane emissions, but this source has declined as coal-mining activity in the UK has reduced. Emissions from all major methane sources have declined, contributing to the overall reduction of 62% since 1990.
Carbon Dioxide as Carbon
Carbon dioxide contributes to climate change due to its positive radiative forcing effect and it is the most significant greenhouse gas emitted in the UK. Total emissions are dominated by those from power stations, refineries and other users of fossil fuels (including transport, domestic and industrial sectors). Fuel combustion contributed more than 94% of carbon dioxide emissions in 2022, excluding net carbon stock changes in Land Use Land Use Change and Forestry (LULUCF).