Assessment of pollutant emission in Poland from various categories of transport

The present study refers to the emission of pollutants in Poland from different transport categories in the period 1990–2020 [Poland's Informative Inventory Report 2022]. The aim of the study was to assess the contribution of pollutant emissions from road transport to pollutant emissions from total transport methods.

The analysis was carried out with authorised results from the pollutant emissions inventory carried out by the National Centre for Emissions Management (KOBiZE) at the Institute of Environmental Protection – National Research Institute (IOŚ-PIB). The results obtained by KOBiZE are reported to the United Nations Economic Commission for Europe (UNECE) Convention on Long-Range Transboundary Air Pollution (CLRTAP) and to the European Union compliant with the Directive (EU) 2016/2284 of the European Parliament and of the Council of 14 December 2016 on the reduction of national emissions of certain atmospheric pollutants (the EU National Emission Ceilings Directive). Data included in the reports prepared by KOBiZE is also used in the reports published by Statistics Poland (GUS). The following categories [EEA/EMEP Emission Inventory Guidebook 2019, Poland's Informative Inventory Report 2021] were considered in the present study: –

road transport,

Along with the recommendations of the European Monitoring and Evaluation Programme - European Environment Agency (EMEP EEA) for reporting on the national annual emission of pollutants, the additional substances adopted are listed in Table 1 [EEA/EMEP Emission Inventory Guidebook 2019].

The emissions of pollutants harmful to health and those enhancing the intensification of the greenhouse effect in the atmosphere (the increase of greenhouse gases) are also reported.

In the present study, the pollutants harmful to the health of living beings were examined. The following substances were selected for the analyses carried out under the present study: –

nitrogen oxides,

There were two reasons behind the selection of the above substances. The first reason is that the emissions of nitrogen oxides, non-methane volatile organic compounds, particulate matter PM2.5, particulate matter PM10, total suspended particulate matter TSP, and carbon monoxide are related to the emissions of pollutants that are subject to the regulations for motor vehicles in force in Europe (commonly called ‘Euro’) [DieselNet: Engine & Emission Technology; Worldwide emission standards 2020/2021; Worldwide emissions standards heavy duty and off-highway vehicles. 2016/17]. The second reason is the issue of substances, the content of which is limited in fuels, such as lead and sulfur [DieselNet: Engine & Emission Technology; Worldwide emission standards 2020/2021; Worldwide emissions standards heavy duty and off-highway vehicles. 2016/17]. In actual fact, the presence of lead and sulfur in fuels has been radically reduced [Advanced Combustion and Emission Control Roadmap 2018; DieselNet: Engine & Emission Technology; Worldwide emission standards 2020/2021; Worldwide emissions standards heavy duty and off-highway vehicles. 2016/17].

The topics related to inventorying pollutant emissions from various source categories, with respect to pollutants harmful to the health of living beings, as well as greenhouse gases, have been developed in many centres worldwide [1990–2015 air pollutant emission inventory report; Air Quality Pollutant Inventories for England, Scotland, Wales and Northern Ireland: 2005–2019; Bebkiewicz et al. 2020b; Bebkiewicz et al. 2021; Bebkiewicz et al. 2021c; Bebkiewicz et al. 2021b; Bebkiewicz et al. 2020a; Chłopek et al. 2018b; EEA/EMEP Emission Inventory Guidebook 2019; Emissions of air pollutants from transport. European Environment Agency 2021; Ireland's Final Greenhouse Gas Emissions 2021; Kara et al. 2014; Keller 2010; Kurien et al. 2018; Lemana 2016; Lestari et al. 2020; Poland's Informative Inventory Report 2022; Progiou, Ziomas 2011; Saikawa 2012; UK Spatial Emissions Methodology 2019]. Most publications contain annual emission data for individual countries [1990–2015 air pollutant emission inventory report 2016; Advanced Combustion and Emission Control Roadmap March 2018; Air Quality Pollutant Inventories for England, Scotland, Wales and Northern Ireland: 2005–2019; Bebkiewicz et al. 2020b; Bebkiewicz et al. 2021a; Bebkiewicz et al. 2021c; Bebkiewicz et al. 2021b; Bebkiewicz et al. 2020a; Chłopek et al. 2018b; Ireland's Final Greenhouse Gas Emissions 2021; Poland's Informative Inventory Report 2022; Saikawa 2012] or centres [Bebkiewicz et al. 2020b; DieselNet: Engine & Emission Technology; Kara et al. 2014; Kurien et al. 2018; Lemana 2016; Lestari et al. 2020; UK Spatial Emissions Methodology 2019].

The pertinent studies [Emissions of air pollutants from transport. European Environment Agency 2021; Keller 2010] contain forecasts of pollutant emissions from transport.

The subject literature also includes the methodology used in the emissions inventory [1990–2015 air pollutant emission inventory report 2016; Air Quality Pollutant Inventories for England, Scotland, Wales and Northern Ireland: 2005–2019; Chłopek et al. 2018a; EEA/EMEP Emission Inventory Guidebook 2019; UK Spatial Emissions Methodology 2019]. In Poland, the pollutant emissions inventory carried out by KOBiZE at IOŚ-PIB uses the methodology recommended by EMEP EEA [EEA/EMEP Emission Inventory Guidebook 2019]. The methodology is legitimately described in the article [Chłopek et al. 2018a]. The team of authors from IOŚ-PIB has carried out comprehensive, up-to-date analyses of pollutant emissions from road transport. The studies [Bebkiewicz et al. 2020b; Chłopek et al. 2018] comprised the analyses of the emission of greenhouse gases in 1988–2017. The studies [Bebkiewicz et al. 2021b; Bebkiewicz et al. 2020a] concerned the analysis of road transport emissions of substances harmful to the health of living beings, and above all, particulate matter emissions. The studies from Bebkiewicz et al. (2021b; 2020a) focused on the influence of road vehicle operating conditions on emissions. In Bebkiewicz et al. (2021b), the effects on pollutant emissions from the following vehicle operation conditions were examined: urban, rural, highways, and expressways.

Whereas in Bebkiewicz et al. (2021b), the effect of thermal condition of internal combustion engines on pollutant emissions was examined. The authors from IOŚ-PIB have not yet published any papers containing the results of the studies on the inventory of pollutant emissions from the categories of transport other than road transport. As a matter of fact, this topic has not been dealt with in the subject literature. An exception is the paper Emissions of air pollutants from transport. European Environment Agency 2021, which presents an overview of the shares of pollutant emissions from different transport categories in European countries – averaged for the reporting years – and refers to the changes in the relative annual emissions of the studied pollutants from the total transport over the period of 1990–2017.

The present study focused on changes in the national annual emissions of selected pollutants from specific transport categories in Poland in the period 1990–2020. There were also examined the shares of the national annual emissions of the pollutants from the transport categories under the study in the national annual emission from the total transport. Furthermore, the sensitivity of the annual national pollutant emission in terms of the transport categories and the substances emitted was assessed using an analysis of the coefficient of variation in the annual national pollutant emissions.

Figures 1–8 present process in the national annual emissions (E_a) of the examined substances from the specific transport categories in the years 1990–2020.

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Even with the substantial intensification of transport [Poland's Informative Inventory Report 2022], the national annual emissions of the pollutants under the study show a decrease over the consecutive years of the study period. This is particularly noticeable in the case of carbon monoxide and non-methane volatile organic compounds, i.e. the products of incomplete and half-finished combustion of fuels in engines, as well as in the case of sulfur compounds and lead compounds. The decrease in emissions of incomplete and half-finished combustion products is due to the implementation of numerous technical solutions in internal combustion engines, enabling the formation of the combustible mixture in the cylinders, with precise composition and spatial uniformity adjusted to the engine type (spark ignition engines, spark ignition engines for combustion of mixtures, compression ignition engines), as well as thanks to the use of the catalytic exhaust gas after-treatment systems [Advanced Combustion and Emission Control Roadmap 2018; DieselNet: Engine & Emission Technology Online; Kurien et al. 2018; Lemana 2016; Worldwide emission standards 2020/2021; Worldwide emissions standards heavy duty and off-highway vehicles. 2016/17]. The introduction of the latter solution was demanded to radically reduce sulfur and lead contents in fuels, as the presence of these substances in fuel put catalytic reactors at risk of destruction. Lead and sulfur compounds have adverse effects on the active surface of catalytic reactors. Obviously, changes in the levels of sulfur and lead compounds contained in fuels resulted in changes in fuel composition and the technology used for its production, e.g. application of isoalkane additives to petrols (reformed petrols) so as to ensure sufficient resistance to engine knock.

Essential reductions in the national annual emissions of sulfur compounds since 2005 and of lead compounds since 2001 have occurred as a result of new limits for sulfur and lead contents in fuels.

Reduced contents of sulfur and lead compounds in fuel have resulted in the environmental benefit – a significant decrease in the emissions of these compounds.

As far as nitrogen oxides and particulate matter are concerned, the progress in the reduction of their emissions is slower when compared to carbon monoxide and organic compounds. In the case of carbon monoxide and organic compounds, there still occur difficulties in catalytic treatment of exhaust gases so as to decrease the emissions of these substances [Advanced Combustion and Emission Control Roadmap 2018; Kurien et al. 2018; Lemana 2016; Worldwide emission standards 2020/2021; Worldwide emissions standards heavy duty and off-highway vehicles. 2016/17].

It is noteworthy that practically all emissions of lead compounds originate from road transport as spark ignition engines fuelled with petrol containing lead compounds are used in this transport category. Other transport sectors use mainly compression ignition engines. In the case of carbon monoxide emissions, the situation is similar to that with lead compounds – carbon monoxide emissions come mainly from spark ignition engines, i.e. mainly from road transport.

Figures 9–16 show changes in the shares of the national annual emissions of the pollutants from the transport categories under the study in the national annual emission from the total transport.

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In the case of nitrogen oxides, the foremost source of emissions is the category of road vehicles, followed by mobile machinery. The dominance of the share of nitrogen oxides emission in the case of road vehicles results, first of all, from the number and the intensity of use of means of transport in this category [Poland's Informative Inventory Report 2022]. Mobile machines are powered by compression ignition engines, most often with environmental properties because their pollutant emissions are much higher than those of automotive vehicle engines [DieselNet: Engine & Emission Technology Online; Worldwide emissions standards heavy duty and off-highway vehicles. 2016/17].

In the case of non-methane volatile organic compounds and carbon monoxide, a similar pattern is observed. However, the dominance of the emissions of non-methane volatile organic compounds and carbon monoxide from road vehicles is higher when compared to nitrogen oxides. Trends analogous to that of of nitrogen oxides are observed in the shares of the national annual emissions of sulfur oxides.

As for the share of the national annual emissions of particulate matter, in the 21st century, there has been observed a trend toward increasing. At the same time, there has occurred a tendency to decrease for the share of the national annual emissions from mobile machines.

The share of the national emission of lead shows a significant step change in 2000, which resulted from the introduction of petrol with trace contents of lead compounds (‘unleaded petrol’) into the operation of motor vehicles. Yet, high lead compound contents have remained in traditional aircraft fuel.

In Figures 17 and 18, a different presentation layout was used to better visualise the influence of individual indicators, show the coefficient of variation of the national annual emission of the pollutants under the study from individual transport categories.

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Figure 18

The coefficient of variation of a quantity characterises the sensitivity of this quantity to other physical quantities or categories of sets for which the coefficient of variation is determined. The coefficient of variation of the national annual emission of the examined pollutants from particular transport categories varies considerably, both for the types of substances and for the categories of transport.

The mean value of the coefficient of variation of the national annual emission is smallest for nitrogen oxides and for air transport means, and highest for sulfur oxides and water transport means.

Based on the results of the present study on the national annual emissions in Poland over the period 1990–2020, the following conclusions can be formulated: 1)

Transport is a sector with very dynamic development patterns [Poland's Informative Inventory Report 2022]. It poses an obvious threat to the environment, primarily due to the emissions of pollutants. At the same time, efforts have been made to improve the performance of transport means – in particular, their engines – with respect to environmental impacts. This is particularly evident in the case of the effectiveness of the measures taken to reduce pollutant emissions from internal combustion engines. Figures 19 and 20 show schematically the values of the specific emissions of nitrogen oxides and particulate matter from compression ignition engines of vehicles with the reference mass higher than 2.61 Mg (trucks and buses) observed in static tests (the European Stationary Cycle [ESC] for Euro V regulations and the World Harmonized Stationary Cycle [WHSC]) for Euro VI regulations, as well as in dynamic tests (the European Transient Cycle [ETC] for Euro V regulations and the World Harmonized Transient Cycle [WHTC]) for Euro VI regulations

Changes were made for the test methods at the level of Euro VI emissions. The ESC static test was replaced by the WHSC test and the ETC dynamic test by the WHTC test. Nevertheless, the test results are comparable.

Figure 19

Figure 20

The analysis of the national annual emissions of pollutants from transport in Poland over the period 1990–2020 unambiguously confirms the effectiveness of rational measures aimed at reducing the harmful impact of transport on the environment. This is possible not only as a result of technical measures taken with respect to the construction of means of transport and, above all, the internal combustion engines that drive them, but also due to the improvement of consumables, chiefly fuels. An important role is also played by organisational activities in transport, mainly the rationalisation of transport works. These activities are aimed at reducing, as far as possible, the need to use transport, and they include the partial replacement of matter transport by transmission of information, i.e. through information networks.