Greenhouse gas emissions and air pollutant from transport.

Trends in emissions of greenhouse gases and pollutants from the transport sector have been balanced since 1990. More information on emissions trends from the transport sector in Slovakia.

Total emissions

Transport is a major source of greenhouse gases and air pollutants. Despite the improving efficiency of in-vehicle engines over the last decade, road transport in particular, is a major source of emissions of carbon dioxide (CO2), nitrogen oxides (NOx), carbon monoxide (CO), particulate matter (PM) and copper.

The overall increase in demand for passenger and freight transport, insufficient compliance with and control of specified emission standards in the past, led to the non-compliance of preconditions towards the goal of reducing emissions. A good example is the average NOx emissions from diesel engines of the EURO 5 emission standards when tested in real operation. Here, emissions were at about the same level as previous technologies set by older standards, and in some cases even exceeding the limits set by standards before the Euro standard. Thus, these emissions did not decrease much, which means that the reduction was not as high as expected.

Total greenhouse gas emissions from the transport sector in the last year (2020) accounted for 19% of all greenhouse gas emissions in Slovakia, which is 7 069 Gg CO2  eq. The increase in these emissions compared to the base reference year 1990 is more than 3.6%. Between years 2019 and 2020 the first emission decreasion was observed (3.6%) due to the COVID pandemic. Road transport has the largest share on transport sector - almost 94%.

NOx emissions are mainly produced by the combustion of diesel. In 2020, it was 18 Gg, which is about 33% of all nitrogen oxide emissions in Slovakia. Despite the high values, Slovakia has managed to reduce these emissions by 50% over the last 15 years, while the reduction compared to 1990 is 58%. This reduction is mainly due to the improvement of in-vehicle engine technology and the partial electrification of rail transport. Slowing down the reduction of these emissions was a fraud known as the "diesel gate". As part of this fraud, the on-board computer of certain vehicles was supposed to temporarily reduce the emissions produced by the engine by changing the engine settings in order to meet the emission limits (mentioned above) during the tests.

To a lesser extent, transport is responsible for emissions of other pollutants such as carbon monoxide (CO) and dust, especially 2.5 micrometres particles (PM2,5). Their current share in total emissions in Slovakia is about 6% for PM2,5 and 3% for CO, in the case of carbon monoxide it has significantly decreased in the last 15 years (up to 93%). In the case of particles, this decrease is "only" 65%. In absolute values, it is 13.69 Gg for carbon monoxide and 0.98 Gg for particulate matter. Behind the significant reduction in carbon monoxide emissions is again an increase in the efficiency of fuel combustion in vehicle engines. Dust emissions are difficult to reduce, as they are mainly produced by tire, road and brake system wear. The brake systems are also responsible for high copper values. Emissions of copper particles from the braking system are approximately 7 tonnes, annually. The production of dust particles and copper is thus significantly affected by the driving style.


Trends in emissions by individual types of fuels

Trends in emissions of greenhouse gases and pollutants from the transport sector by individual types of fuels have been balanced since 1990. More information on emissions trends from the road transport sector - combustion by types of fossil fuels in Slovakia.


Emissions by fuels

Combustion of diesel (65%), petrol (19%) and natural gas (6%) and, in terms of pollutants, biofuels (5%) have the largest share in emissions. Aviation fuels and LPG together account for about 1.5% of transport fuel consumption. A significant share of diesel is due to its use in several modes of transport, such as road, rail and shipping. The share of biomass-based fuels is increasing every year, which is due to the obligation to mix biofuels into fuels used in road and rail transport.