Sources and emissions of air pollutants in Europe

Trends in air pollutants emissions, 2005-2020

Total emissions^[1] of all pollutants in the EU-27 declined in 2020, maintaining the overall downward trend observed since 2005. Figure 1 shows the trend in total emissions of the main air pollutants, indexed as a percentage of their value in the reference year 2005 and set against gross domestic product (GDP) as a percentage of the 2005 value. 

From 2005 to 2020, emissions of particulate matter with a diameter of 10 micras (μm) or less (PM₁₀) and 2.5μm or less (PM_2.5) fell by 30% and 32%, respectively. Notably, ammonia (NH₃) had the lowest reduction in emissions of only 8% over this period. Ammonia is an important precursor gas that contributes to the formation of secondary particulate matter. Furthermore, emissions of methane (CH₄) declined by only 17%. CH₄ is a potent greenhouse gas that drives climate change and is also an ozone (O₃) precursor. The principal source of both NH₃ and CH₄ emissions is the agriculture sector.

By contrast, emissions of sulphur dioxide (SO₂) fell significantly from 2005 to 2020, with a decrease of 79%. This was mainly due to the reduced use of coal over the period. Major reductions were also seen for nitrogen oxides (NO_X), black carbon (BC), carbon monoxide (CO) and non-methane volatile organic compounds (NMVOCs), with declines of 48%, 46%, 42% and 31%, respectively. 

Figure 1. 2005-2020 Trends in EU-27 emissions of NH₃, CH₄, primary PM₁₀, NMVOCs, primary PM_2.5, CO, BC, NO_X and SO₂, as percentages of 2005 levels, set against EU-27 GDP as a percentage of 2005 GDP

The EEA briefing ’National Emissions reduction Commitments Directive reporting status 2022’ summarises progress towards reducing emissions of key air pollutants regulated under EU legislation at the EU and Member State levels. The biggest challenge for the period 2020-2029 will be reducing ammonia emissions: 11 Member States need to further cut emission levels. Looking forward to 2030, almost two thirds of Member States will need to reduce emissions of ammonia, nitrogen oxides and fine particulate matter to meet their 2030 commitments.

Figure 2 shows trends in the total emissions of heavy metals and benzo[a]pyrene (BaP) in the EU-27, indexed as a percentage of their value in the reference year 2005 and set against EU-27 GDP as a percentage of the 2005 value. Emissions of nickel (Ni) and arsenic (As) fell by more than 60% (64% and 62%, respectively), while mercury (Hg), lead (Pb) and cadmium (Cd) emissions fell by 51%, 49% and 40%, respectively. Emissions of BaP fell by only 18%.

Figure 2. 2005-2020, Trends in EU-27 emissions of BaP, cadmium, lead, mercury, arsenic and nickel, as percentages of 2005 levels set against EU-27 GDP as a percentage of 2005 GDP

During the period 2005-2020, emissions showed a significant absolute decoupling from economic activity. Absolute decoupling occurs when an environmental impact variable, such as air pollutant emissions, remains stable or decreases, while GDP increases, leading to lower emissions of key air pollutants for each unit of GDP produced annually.

Both Figures 1 and 2 show that EU-27 air pollutant emissions declined between 2005 and 2020, while EU-27 GDP increased. However, because of the lockdowns implemented to stop the spread of COVID-19, and the subsequent decrease in some economic activities, GDP fell in 2020. The greatest decoupling is seen for SO₂, followed by NO_X, BC, CO and certain metals (Ni, As and Hg).

The decoupling of emissions from economic activity may be the result of a combination of factors, such as increased regulation and policy implementation, fuel switching, technological improvements and improvements in energy or process efficiencies. The increase in the EU’s consumption of goods produced outside the EU also plays a role in falling domestic emissions. 

Main sources of air pollutants in 2020

The economic sectors that are the upstream sources of air pollutant emissions vary by pollutant. Figure 3 depicts the contributions of the main source sectors to the emissions of key air pollutants in the EU-27 in 2020.

• The primary source of particulate matter, both PM₁₀ and PM_2.5, was energy consumption in the residential, commercial and institutional sector. It was responsible for 44% and 58% of emissions, respectively. The manufacturing and extractive industry, and the road transport sector, were also significant sources of both pollutants, while agriculture was an important source of PM₁₀.
• The agriculture sector was the principal source of NH₃, responsible for 94% of emissions.
• The agriculture sector also contributed more than half, 56%, of all CH₄ emissions. The waste sector was the second-largest source of CH₄ at 27%.
• The road transport sector was the main source of emissions of NO_X emissions, responsible for 37%, followed by agriculture at 19%, and the manufacturing and extractive industry at 15%.
• Energy consumption in the residential, commercial and institutional sector was the main source of CO and BC emissions, contributing to 46% and 37% of total emissions, respectively.
• The manufacturing and extractive industry sector was the main source of NMVOCs, responsible for 47% of emissions. Agriculture was the second-largest contributor at 27%.
• Energy supply was the principal source of SO₂ emissions at 41%, with the manufacturing and extractive industry sector being the second-largest contributor at 37%.

Figure 3. Contributions to EU-27 emissions of BC, CO, NH₃, NMVOCs, NO_X, primary PM₁₀, primary PM_2.5, SO₂ and CH₄ from the main source sectors in 2020

Figure 4 shows the contribution that the main source sectors made to EU-27 emissions of heavy metals and BaP in 2020. 

• The manufacturing and extractive industry sector was the principal source of all heavy metal emissions, except nickel. This sector was responsible for 60% of lead, 54% of cadmium, 44% of mercury and 42% of arsenic emissions.
• For arsenic and mercury, the energy supply sector was the second-largest source of emissions, responsible for 39% and 38% of total emissions, respectively. The residential, commercial and institutional sector was the third most important for both pollutants at less than 10%.
• For lead, the second-largest source of emissions was road transport, at 17% of emissions, followed by the residential, commercial and institutional sector, at 12% of emissions.
• For cadmium, the residential, commercial and institutional sector, and the energy supply sector, were the second and third most important sources, responsible for 22% and 15% of total emissions, respectively.
• The energy supply sector was the main source of nickel emissions, responsible for 42%, with the manufacturing and extractive industry sector, and the non-road transport sector, contributing 27% and 18% of emissions, respectively.
• The residential, commercial and institutional sector was the primary source of BaP emissions, responsible for 85%.

Figure 4. Contributions to EU-27 emissions of arsenic, BaP, cadmium, mercury, nickel and lead from the main source sectors in 2020