###### Abstract
The aforementioned regulations comprise general and specific requirements for the testing of motor vehicles and internal combustion engines as regards their emissions. In the case of particulate matter, the object of testing is the emission (mass) of particulates and the number of particulates. The physical quantities described below are assumed as criterion quantities [30; 31]. For vehicles with a reference mass of less than 2.61 Mg (passenger cars, light trucks and minibuses), the criterion quantities are as follows:  
* The specific distance particulate matter emission (\(\mathrm{b_{PM}}\))  
The specific distance particulate matter emission is the derivative of particulate matter emission (\(\mathrm{m_{PM}}\)) relative to the distance(s) travelled by the vehicle. \[\mathrm{b_{PM}}=\frac{\mathrm{m_{PM}}}{\mathrm{ds}}, \tag{1}\]
* The specific distance number of particulate matter (\(\mathrm{b_{PN}}\)):  
The specific distance number of particulate matter is the derivative of the particulate matter (PN) relative to the distance(s) travelled by the vehicle. \[\mathrm{b_{PN}}=\frac{\mathrm{PN}}{\mathrm{ds}}, \tag{2}\]  
For internal combustion engines of vehicles with a reference mass greater than 2.61 Mg (trucks and buses):  
* The specific brake emission of particulate matter (\(\mathrm{e_{PM}}\))  
The specific brake emission of particulate matter is the derivative of the emission of particulate matter (\(\mathrm{m_{PM}}\)) relative to the internal combustion engine work (L). \[\mathrm{e_{PM}}=\frac{\mathrm{m_{PM}}}{\mathrm{dL}}, \tag{3}\] \begin{table}
\begin{tabular}{c c} \hline \hline
**Identification Data** & **Issue Covered by the Legal Act** \\ \hline Commission Regulation (EC) & Type approval of motor vehicles with respect to emissions from light passenger and commercial vehicles (Euro 5 and Euro 6) and on access to vehicle repair and maintenance in-formation, European Commission (EC), Official J. \\
20 June 2007 & European Union, L 171, 2007. \\ Commission Regulation (EU) & Amending Regulation (EC) No. 692/2008 as regards \\
2016/427 of 10 March 2016 & emissions from light passenger and commercial vehicles (Euro 6), Verifying Real Driving Emissions, Official J. \\ European Union, L 82, 2016. \\ Commission Regulation (EC) No. 692/2008 as regards \\ Commission Regulation (EU) & emissions from light passenger and commercial vehicles (Euro 6), Verifying Real Driving Emissions, Official J. \\ European Union, L 109, 2016. \\ Supplementing (EC) No 715/2007 of the European \\ Parliament and of the Council on type-approval of motor \\ vehicles with respect to emissions from light passenger and commercial vehicles (Euro 5 and Euro 6) and on access to vehicle repair and maintenance information, amending \\ Directive 2007/46/EC of the European Parliament and of the \\ Council, Commission Regulation (EC) No 692/2008 and \\ Commission Regulation (EU) No 1230/2012 and repealing \\ Commission Regulation (EC) No 692/2008. Official Journal of \\ the European Union. L 175. \\ \hline \hline \end{tabular}
\end{table} 
Table 2: _Cont._The specific brake number of particulate matter (\(\mathrm{e_{PN}}\))  
The specific brake number of particulate matter is the derivative of the particulate matter number (PN) relative to internal combustion engine work (L). \[\mathrm{e_{PN}}=\frac{\mathrm{PN}}{\mathrm{dL}}, \tag{4}\]  
Figure 1 presents the limits of the specific brake emissions of particulate matter for stages Euro V and Euro VI tested by static WHSC (World Harmonized Stationary Cycle) and in the dynamic tests ETC (European Transient Cycle) for Euro V and WHTC (World Harmonized Transient Cycle) for Euro VI [30; 31]. The specific brake number of particulate matter is limited from stage Euro VI onwards. The progress is clearly visible in the protection of the environment against particulate matter emitted from self-ignition engines for heavy-duty vehicles--a twofold reduction in the limits for the emissions of particulate matter in the static test and a threefold reduction in the dynamic test.