The emission class (EU stage) regulates permissible exhaust gas limit values for diesel engines in mobile machinery and equipment (NRMM — Non-Road Mobile Machinery). Since January 2019, Stage V applies to new machines, imposing the strictest requirements for particle number, particle mass, nitrogen oxides (NOx), hydrocarbons (HC), and carbon monoxide (CO).
The development proceeded through several stages: Stage I (1999), II (2001), IIIA (2006), IIIB (2011), and IV/V (2014/2019). Each stage significantly tightened limit values — Stage V reduces particles by over 97% compared to unregulated engines. Compliance requires diesel particulate filters (DPF), SCR catalytic converters (AdBlue), and diesel oxidation catalysts (DOC).
For construction contractors, emission class is also economically relevant: many municipalities and clients require minimum emission classes in tenders (often Stage IIIB or V). For work in city centers, tunnels, or enclosed halls, emission class can determine contract award. Retrofit solutions (retrofit-DPF) allow upgrading of older machinery.