###### Abstract  
The aim of this study is to investigate the environmental hazards posed by solid particles resulting from road transport. To achieve this, a methodology used to inventory pollutant emissions was used in accordance with the recommendations of the EMEP/EEA (European Monitoring and Evaluation Programme/European Economic Area). This paper classifies particulates derived from road transport with reference to their properties and sources of origin. The legal status of environmental protection against particulate matter is presented. The emissions of particulate matter with different properties from different road transport sources is examined based on the results of Poland's inventory of pollutant emissions in the year 2018. This study was performed using areas with characteristic traffic conditions: inside and outside cities, as well as on highways and expressways. The effects of vehicles were classified according to Euro emissions standards into the categories relating to the emissions of different particulate matter types. The results obtained showed that technological progress in the automobile sector has largely contributed to a reduction in particulate matter emissions associated with engine exhaust gases, and that this has had slight effect on particulate matter emissions associated with the tribological processes of vehicles. The conclusion formed is that it is advisable to undertake work towards the control and reduction of road transport particulate matter emissions associated with the sources other than engine exhaust gases. particulate matter; TSP; PM2.5; PM10; road transport; environmental protection +
Footnote †: journal: Applied Sciences  
12 May 2021  
Accepted: 28 June 2021  
Submitted: 30 June 2021  
the scope of a single study. Therefore, it was decided to use the standard produced by the pollutant emission inventory procedure, in accordance with the 2006 IPCC Guidelines for National Greenhouse Gas Inventories and the EEA/EMEP Emission Inventory Guidebook 2019 [8]. In this procedure, all aspects of the formation of solid particles in connection with the operation of motor vehicles are included in a systemic and contractual manner as a standard in the inventory of pollutant emissions. Particulate matter is defined as a mixture of fine particles suspended in a gaseous dispersive phase such as air [5; 6; 14; 15; 16; 17; 18]. Particles are classified by their conventional dimensions, which depend on their average aerodynamic diameter. They are distinguished as [5; 6; 7; 8; 19; 20; 21; 22; 23]:  
* total suspended particles (TSP)--with an average aerodynamic diameter of less than 300 \(\upmu\)m;
* fine particles PM10--with an average aerodynamic diameter of less than 10 \(\upmu\)m;
* fine particles PM2.5--fine inhalable particles with an average aerodynamic diameter less than 2.5 \(\upmu\)m and colloidal fragmentation;
* ultrafine particles PM1--with an average aerodynamic diameter of less than 1 \(\upmu\)m, practically invisible, distinguished in tests on internal combustion engines (particles with an average aerodynamic diameter of less than 100 nm, called nanoparticles, are separated from PM1; sometimes solid particles with dimensions smaller than 50 nm are also distinguished). Particulate matter emissions from road transport are modeled depending on the characteristics of motor vehicles, including their intended use and conventional size, environmental quality of internal combustion engines as regards their emissions, and traffic conditions [6; 7; 8; 10; 11; 21; 23; 24; 25]. Particulate Matter Environmental Hazards and the Protection of Environment against Particulate Matter Emission from Road Transport--Legal Status  
Particulate matter has adverse effects both on human health and the natural environment [5; 9; 14; 26; 27], including soil, water and living organisms. Once the air contains more water vapor, the aerosol's hygroscopic growth causes an increase in PM that results in poorer visibility and promotes the formation of fog and cold smog [28].