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With the introduction of policy measures in recent decades, the emissions of most air pollutants from transport in the EU-27 have decreased. Reductions in the road transport sector account for the greatest share of this progress, while emissions from the shipping and aviation sectors increased with some pollutants. The dramatic reduction in transport volumes linked to the COVID-19 pandemic led to significant reductions in emissions for 2020, but this is likely to be temporary. An upturn in pollution from transportation is already visible for 2021 alongside the rebound in transport volumes.
Figure 1. Emissions of pollutants from transport in EU-27
Pollutants emitted by transport activities contribute to ambient air pollution and put significant pressure on the environment and human health in Europe. Significant policy efforts, although with differences across modes, have addressed transport-related air pollution in recent decades and have led to some notable improvements.
For instance, the Ambient air quality Directive set limits or target values for concentrations of pollutants in the ambient air, while the NEC Directive sets emission reduction commitments on total national emissions for five air pollutants (NOx, SO2, NMVOC, NH3 and PM2.5). Recently, the European Commission proposed a revision of the Ambient air quality Directive, to more closely align air quality standards with WHO guidelines, while putting the EU on a trajectory to achieve the zero pollution ambition by 2050.
Emissions from the transport sector are further regulated by vehicle emissions standards and fuel quality requirements . Local and regional air quality management plans, including initiatives such as low-emission zones and congestion charges in cities, are active in many areas. SOx and NOx emissions from international shipping are regulated by Annex VI to MARPOL Convention of the International Maritime Organisation. SOx requirements are transposed in EU law by the Directive on sulphur content in certain liquid fuels including marine fuels.
Together, such policies have delivered progress in reducing the emissions of many pollutants from the transport sector. Between 1990 and 2021 (thus including COVID-19 pandemic effects) across the EU-27, emissions of nitrogen oxides (NOx) from transport decreased by 53%, sulphur oxides (SOx) by 83%, carbon monoxide (CO) by 89%, methane (CH4) and non-methane volatile organic compounds (NMVOCs) by 64% and 89% respectively. At the same time, between 2000 and 2021, EU-27 transport emissions of particulate matter (including non-exhaust emissions) with particle diameter of 10µm/2.5µm or less (PM10/2.5) decreased by 47%/56% respectively.
The onset of the COVID-19 pandemic had an influence on these figures, due to the significant contraction in transport volumes during 2020 and 2021. Indeed, the same reductions calculated between 1990 (2000 for PM) and 2019 were considerably lower for some pollutants: 42% for NOx, 60% for SOx, 87% for CO, 74% for CH4, 88% for NMVOCs, 39% for PM10, 47% for PM2.5.
At the same time, two air pollutants have demonstrated substantial growth in recent decades. Between 1990 and 2021, transport emissions of ammonia (NH3) increased by 109% (136% in 1990-2019) while nitrous oxide (N2O) increased by 28% (39% in 1990-2019). Although transport contributions of NH3 emissions are limited compared to agriculture and other sectors, their impact on air quality, especially within cities, is reported to be very high . N2O, while a powerful greenhouse gas, is also currently considered a dominant ozone depleting substance .
Figure 2. Variations (1990-2021) in the emissions of pollutants from transport by mode in EU-27
Although most pollutant emissions declined since 1990, the situation is heterogeneous across transport modes. This in part reflects differences in the stringencies of emissions standards.
Road transport has significantly reduced its pollutant emissions, with the exception of the compounds NH3 and N2O. Their recent increase is mostly due to new catalytic systems for the reduction of NOx . For PM, reductions are smaller due to an increase in non-exhaust emissions such as brakes and tyre abrasion. These will become more relevant with decarbonisation of the sector and increase in vehicle mass due to batteries.
The reduction of pollutant emissions seen in aviation in 2021 is mostly due to the pandemic. If calculated for 1990-2019, none of the pollutants reported decreased for international aviation. Only CO and NMVOC would have shown a large reduction (>20%) in domestic aviation. This can be partially explained by the difference in demand evolution and the technology used in domestic and international aviation. It is important to note that domestic and international labels for both aviation and shipping refer to Member States (i.e. within the borders of member states or crossing them).
Similar considerations hold for the maritime sector, especially international navigation. CH4, CO, N2O, NH3, NMVOC, NOx were all between 11% to 57% higher in 2019 than 1990 levels. For domestic navigation, all pollutants decreased between 64% to 2% in 2019.
The mobility system contributes to air pollution emissions and additional information on its relative contribution to the overall situation in Europe can be found consulting the interactive data viewer.