This indicator shows changes in the emissions of the 5 key air pollutants: sulphur dioxide (SO2), fine particulate matter (PM2.5), nitrogen oxides (NOx), non-methane volatile compounds (NMVOCs) and ammonia (NH3). Air pollution has negative impacts on human health and the environment. Long-term exposure to particulate matter contributes to the risk of developing cardiovascular diseases and lung cancer. As well as being emitted directly, particulate matter can be formed in the atmosphere from reactions between other pollutants, of which SO2, NOx, NMVOCs and NH3 are the most important. NOx and NH3 emissions can be deposited in soils or in rivers and lakes, for example, through rain. Resulting nutrient nitrogen deposition affects the nutrient levels and diversity of species in sensitive environments, for example, by encouraging algae growth in lakes and water courses and by producing ozone (O3) which damages crops and leads to impacts on wildlife through enhanced nutrient levels.
This indicator is an assessment of pressures on the atmosphere caused by the emissions of 5 key pollutants, which when concentrated in the air or deposited have impacts on human health and ecosystems.
Readiness and links to data
Emissions data are published annually in the Air Quality Pollutant Inventories 2005-2020.
Notes on indicator
Consultation with the devolved administrations led to the agreement to limit updates to historic devolved administration air pollutant inventories to 2005 as this is the base year for legally binding emissions reductions commitments. This also allows more resource to be allocated to the development of more recent years of the time series for which there is better access to updated methods and data. A UK-wide historic time series of emissions remains available back to 1970, published as part of Defra’s annual emissions reporting each February.
Figure A1: Emissions for five key air pollutants in England, 2005 to 2020
Table A1: Emissions for five key air pollutants in England, 2005 to 2020
Trend description for A1
Emissions for all 5 key air pollutants (NH3, PM2.5, NOx, NMVOCs and SO2) in England have fallen over the latest 15 years for which annual, country-level data are available. Emissions of SO2 have seen the greatest reductions, falling by 84% between 2005 and 2020. Emissions of NOx, NMVOCs and PM2.5 have also fallen considerably, by 63%, 43% and 34% respectively; and emissions of NH3 have fallen by 10% over the same period.
More recently, the trends in annual emissions of NH3, PM2.5 and NMVOC have levelled off.
Assessment of change
Assessments for 4 of the air pollutants measured by the A1 indicator (PM2.5, NOx, NMVOCs and SO2) have shown an improvement in the most recent short, medium and long-term time periods. However, although emissions of NH3 are also assessed as improving over the long term, more recent fluctuations have resulted in an assessment of ‘little or no change’ over the medium and short term. More detailed reporting mentioned in the ‘Readiness and links to data’ section for this indicator may provide insights into the factors behind this change in NH3 emissions. This assessment does not consider whether any improvement is on a sufficient scale for meeting targets. Projections towards air emissions targets set at a UK scale are available to supplement this assessment.
Change since 2018 has also been assessed. There has been a decrease (improvement) in the emissions of all 5 air pollutants included within this indicator. However, this result is based on only 3 data points so should be considered as indicative and not evidence of a clear trend.
Further information on this assessment, along with details on the methodology, is provided in the Assessment background page. Summaries by 25 Year Environment Plan goal and information on indicator links are presented in the Assessment results pages.
Table A1: Assessment of change
|Component||Subcomponent||Period||Date range||Percentage change||Smoothing function||Assessment of change|
|A1||NH3||Short term||2014 to 2019||0.86||Loess||Little or no change|
|A1||NH3||Medium term||2009 to 2019||0.40||Loess||Little or no change|
|A1||NH3||Long term||2005 to 2019||-7.39||Loess||Improvement|
|A1||NMVOCs||Short term||2014 to 2019||-5.20||Loess||Improvement|
|A1||NMVOCs||Medium term||2009 to 2019||-22.42||Loess||Improvement|
|A1||NMVOCs||Long term||2005 to 2019||-41.49||Loess||Improvement|
|A1||NOx||Short term||2014 to 2019||-27.72||Loess||Improvement|
|A1||NOx||Medium term||2009 to 2019||-43.82||Loess||Improvement|
|A1||NOx||Long term||2005 to 2019||-59.20||Loess||Improvement|
|A1||PM2.5||Short term||2014 to 2019||-5.22||Loess||Improvement|
|A1||PM2.5||Medium term||2009 to 2019||-14.85||Loess||Improvement|
|A1||PM2.5||Long term||2005 to 2019||-31.93||Loess||Improvement|
|A1||SO2||Short term||2014 to 2019||-56.85||Loess||Improvement|
|A1||SO2||Medium term||2009 to 2019||-70.63||Loess||Improvement|
|A1||SO2||Long term||2005 to 2019||-82.60||Loess||Improvement|
Note that assessment categories for short, medium and long term were assigned based on smoothed data so percentage change figures in Table A1 may differ from unsmoothed values quoted elsewhere. Percentage change refers to the difference seen from the first to last year in the specified date range.