Emissions of air pollutants in the UK – Particulate matter (PM10 and PM2.5)
Updated 22 February 2023
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1. Why are emissions of particulate matter estimated?
Particulate Matter (PM) is everything in the air that is not a gas and as such it is made up from a huge variety of chemical compounds and materials some of which can be toxic. Due to the small size of many of the particles that form PM some of these toxins may enter the bloodstream and be transported around the body, lodging in the heart, brain and other organs. Therefore, exposure to PM can result in serious impacts to health, especially in vulnerable groups of people such as the young, elderly and those with respiratory problems. As a result, particulates are classified according to size. The UK is currently focused on measuring the fractions of PM where particles are less than 10 micrometres in diameter (PM10) and less than 2.5 micrometres (PM2.5) based on the latest evidence on the effects of PM to health.
Both PM and precursor pollutants that can form it can travel large distances in the atmosphere. A small proportion of the concentrations of PM that people in the UK are exposed to come from naturally occurring sources such as pollen and sea spray (approximately 15 per cent). Another third is transported to the UK from other European countries. However, around half of UK concentrations of PM comes from anthropogenic sources in the UK such as wood burning, and tyre and brake wear from vehicles. As such, it is in the interest of the UK to identify and reduce these anthropogenic emissions where possible.
The Convention on Long Range Transboundary Air Pollution’s amended Gothenburg Protocol (CLRTAP) and the National Emissions Ceiling Regulations (NECR) require the UK to reduce emissions of PM2.5 by 30 per cent compared to emissions in 2005 by 2020 and in each subsequent year until 2029. The NECR also requires the UK to reduce emissions by 46 per cent compared to emissions in 2005 by 2030.
2. Trends in total annual emissions of PM10 and PM2.5 in the UK, 1970 to 2021
Figure 3: Annual emissions of PM10 and PM2.5 in the UK: 1970-2021
Note:
- ‘2020-2029 ERC’ refers to the UK emission reduction commitments, as set out in the National Emission Ceilings Regulations 2018/Convention on Long Range Transboundary Air Pollution. These commitments apply to PM2.5 only
Download the data for this chart in CSV format
Annual emissions of PM10 have fallen by 79 per cent since 1970, to 143.9 thousand tonnes in 2021. There was an increase of 8 per cent between 2020 and 2021.
Annual emissions of PM2.5 have fallen by 85 per cent since 1970, to 83.2 thousand tonnes in 2021. There was an increase of 6 per cent between 2020 and 2021.
The UK has seen a 28 per cent reduction in PM2.5 emissions between 2005 and 2021. Therefore, in 2021, the UK did not meet the 30 per cent emission reduction commitment required between 2020 to 2029 as set out in the NECR and the CLRTAP.
Levels of both pollutants generally decreased year-on-year between 1970 and the late-2000s. There are many reasons for this long-term decrease covering most emissions sectors, but the reduction in the burning of coal and improved emission standards for transport and industrial processes are major drivers. Since the late 2000s, annual emissions of particulate matter have fluctuated year-on-year. Considerable decreases in emissions from some sectors have been largely offset by increases in emissions from wood burning in domestic settings and from solid fuel burning by industry (particularly the burning of biomass).
3. Major emission sources for PM10 and PM2.5 in the UK
Figure 4: UK annual emissions of PM10 by 2021 major emission source: 1990, 2005, 2020 and 2021
Notes:
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Industrial processes refer to emissions from specific industrial processes, including some where fuel combustion is a necessary part of the process, such as the production of steel.
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Industrial combustion refers to emissions from industrial burning of fuels, either to generate energy, or to drive mobile machinery. This does not include emissions from combustion in the agricultural, forestry and fishing sectors, or emissions from institutional/commercial combustion.
Download the data for this chart in CSV format
Figure 5: UK annual emissions of PM2.5 by 2021 major emission source: 1990, 2005, 2020 and 2021
Notes:
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Industrial processes refer to emissions from specific industrial processes, including some where fuel combustion is a necessary part of the process, such as the production of steel.
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Industrial combustion refers to emissions from industrial burning of fuels, either to generate energy, or to drive mobile machinery. This does not include emissions from combustion in the agricultural, forestry and fishing sectors, or emissions from institutional/commercial combustion.
Download the data for this chart in CSV format
The burning of fuel used on industrial sites, either to generate energy, or to drive mobile machinery, is a major source of particulate matter emissions, accounting for 26 per cent of PM2.5 emissions and 16 per cent of PM10 emissions in 2021. Emissions from this have increased, largely due to the combustion of biomass fuels which increased by 379 per cent between 2010 and 2021 to represent 18 per cent of total PM2.5 emissions.
These increases have been partially offset by decreases in emissions from industrial processes, which accounted for 34 per cent of PM10 and 13 per cent of PM2.5 in 2021. Emissions from this source have decreased in the long term as the manufacturing output of chemical and steel industries have reduced in the UK, alongside improvements to emission controls for these processes. The largest source in this sector in 2021 was construction and demolition, followed by iron and steel production, dusts generated from spray coating processes, and the quarrying and mining of minerals other than coal.
Domestic combustion is a major source of particulate matter emissions in 2021, accounting for 16 per cent of PM10 emissions and 27 per cent of PM2.5 emissions. Most emissions from this source come from households burning wood in closed stoves and open fires. In the 1970s, 1980s and 1990s, coal use in domestic combustion was the largest source of particulate matter emissions; coal now accounts for a very small proportion of emissions from this source (13 per cent in 2021), while the use of wood as a fuel accounted for 75 per cent of PM2.5 emissions from domestic combustion in 2021. Emissions of PM2.5 from domestic wood burning increased by 124 per cent between 2011 and 2021, to represent 21 per cent of total PM2.5. emissions in 2021.
Road transport remains a major source of PM emissions (12 per cent of PM10 and 13 per cent of PM2.5 in 2021). Exhaust emissions have decreased markedly since 1996 due to stricter emissions standards (by 90 per cent for both PM10 and PM2.5). Non-exhaust road emissions (e.g. brake, tyre and road wear) represented 10 per cent of PM10 and PM2.5 emissions in 2021 and has remained largely unchanged between 1996 and 2021 (8 and 9 per cent lower for PM10 and PM2.5 respectively).
Levels and trends in emissions from specific sources are available for the period 1990 to 2021 through the statistical tables that accompany this release.
4. Sections in this release
Emissions of non-methane volatile organic compounds
Methods and quality processes for UK air pollutant emissions statistics (PDF)