Conventional pollutant emission limits
European Union (European Commission, Parliament, Council, and Member States)
Current Standard
Euro VI, Stage E. Regulation (EC) No 595/2009 implemented by Regulation (EU) No 582/2011.
Applicability
Rigid and tractor trucks of categories N2 and N3, with an axle configuration of either 4×2 or 6×2, and a technically permissible maximum laden mass exceeding 16 tonnes.
History
Europe first introduced heavy-duty vehicle emission standards in 1988. The “Euro” track was established in 1992 with increasingly stringent standards implemented every few years. The heavy-duty Euro standards are numbered using Roman numerals (e.g. Euro I, II….V), whereas light-duty standards use Arabic numbers (e.g. Euro 1, 2…5). Testing is performed on engines alone rather than on complete vehicles, and limit values are expressed in terms of grams per kilowatt-hour (g/kWh) rather than grams per kilometer traveled (g/km).
Many countries have since developed regulations aligned in large part with the European standards; the following are some of the most important rulemaking steps in the heavy-duty engine regulations:
Euro I and II
Euro I standards were introduced in 1992 and followed by the introduction of Euro II regulations in 1996. These standards applied to both truck engines and urban buses; the urban bus standards, however, were voluntary.
Euro III, IV, and V
In 1999, the EU adopted Directive 1999/96/EC, which introduced Euro III standards (2000), as well as the Euro IV/V standards (2005/2008). The directive set voluntary emission limits that are slightly more stringent than Euro V standards for enhanced environmentally friendly vehicles (EEVs).
The following directives were important additions or amendments to the original standards:
- Defeat Devices – In 2001, the European Commission adopted Directive 2001/27/EC which prohibited the use of emission “defeat devices” and “irrational” emission control strategies. This directive would reduce the efficiency of emission control systems when vehicles operate under normal driving conditions to levels below those determined during the emission testing procedure.
- Amended Euro IV and V – Directive 2005/55/EC, adopted by the EU Parliament in 2005, introduced durability and on-board diagnostics (OBD) requirements, and restated emission limits for Euro IV and Euro V, originally published in 1999/96/EC. In a “split-level” regulatory approach, the technical requirements pertaining to durability and OBD—including provisions for emission systems that use consumable reagents—were described by the Commission in Directive 2005/78/EC.
When the Euro IV and Euro V standards were adopted, regulators expected the stringent PM emission standards to require the use of DPFs (Diesel Particulate Filters) in commercial heavy-duty vehicles. However, by tuning their engines for high levels of NOx and fuel economy, and relatively low levels of PM emissions, manufacturers were able to comply with the Euro IV and V emission standards without the use of DPFs. These manufacturers used selective catalytic reduction to lower tailpipe NOx emissions to meet Euro IV and Euro V standards. However, this compliance strategy did not reduce emissions of the smallest and most hazardous particles to the same degree as DPFs.
Euro VI
Euro VI emission standards were introduced by Regulation (EC) No 595/2009 and implemented by Regulation (EU) No 582/2011, the latter establishing all technical details. The regulations have been amended several times since their original adoption to introduce additional elements for the various implementation steps.
Compared to the previous emission standards (Euro V), Euro VI adjusts the emissions limits, extends the durability provisions, and introduces several important new elements. These include:
- New transient and stationary duty cycles. The World Harmonized Transient Cycle (WHTC) and the World Harmonized Stationary Cycle (WHSC);
- Particle number (PN) emission limits;
- New testing requirements—including off-cycle and in-use PEMS testing;
- Stricter OBD requirements;
- Ammonia (NH3) concentration limits.
Technical Standards
Euro I-VI
The following table contains a summary of the emission standards and their implementation dates. Dates in the tables refer to new engine type approvals; the dates for all vehicle sales and registrations are in most cases one year later. Unlike the U.S. program, where engine models must be recertified every year, EU type approvals only occur once per emission level (e.g. Euro V). As part of the Euro VI regulation, particle number (PN) limits were added and should be met in addition to the PM mass-based limits.
| Tier | Date | Test |
CO (g/kWh) |
HC (g/kWh) |
NOx (g/kWh) |
PN (#/kWh) |
PM (mg/kWh) |
Smoke (m-1) |
|---|---|---|---|---|---|---|---|---|
| Euro I | 1992 (< 85 kW) | R-49 | 4.5 | 1.1 | 8.0 | – | 612 | – |
| 1992 (> 85 kW) | 4.5 | 1.1 | 8.0 | – | 360 | – | ||
| Euro II | October 1996 | 4.0 | 1.1 | 7.0 | – | 250 | – | |
| October 1998 | 4.0 | 1.1 | 7.0 | – | 150 | – | ||
| Euro III | Voluntary EEV (October 1999 to January 2013) | ESC & ELR | 1.5 | 0.25 | 2.0 | – | 20 | 0.15 |
| October 2000 | ESC & ELR | 2.1 | 0.66 | 5.0 | – | 100 | 0.8 | |
| Euro IV | October 2005 | 1.5 | 0.46 | 3.5 | – | 20 | 0.5 | |
| Euro V | October 2008 | 1.5 | 0.46 | 2.0 | – | 20 | 0.5 | |
| Euro VI | January 2013 | WHSC | 1.5 | 0.13 | 0.4 | 8.0×1011 | 10 | – |
| Note: EEV – enhanced environmentally-friendly vehicles | ||||||||
| Tier | Date | Test |
CO (g/kWh) |
NMHC (g/kWh) |
CH4a (g/kWh) |
NOx (g/kWh) |
PN (#/kWh) |
PMb (mg/kWh) |
|---|---|---|---|---|---|---|---|---|
| Euro III | Voluntary EEV (October 1999 to January 2013) | ETC | 3.0 | 0.40 | 0.65 | 2.0 | – | 20 |
| October 2000 | ETC | 5.45 | 0.78 | 1.6 | 5.0 | – | 160 | |
| Euro IV | October 2005 | 4.0 | 0.55 | 1.1 | 3.5 | – | 30 | |
| Euro V | October 2008 | 4.0 | 0.55 | 1.1 | 2.0 | – | 30 | |
| Euro VI | January 2013 | WHTC | 4.0 | 0.16c | 0.5 | 0.46 | 6.0×1011 | 10d |
| Notes: (a) For gas engines only (Euro III-V: NG only; Euro VI: NG + LPG). (b) Not applicable for gas-fueled engines at the Euro III-IV stages. (c) THC for diesel engines. (d) PN limit for gas engines applies for Euro VI, Step B and later. |
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Testing
The steady-state engine test used until Euro II, ECE R-49, was replaced by two cycles in 2000, during the Euro III stage. The two replacement tests, still in use today, are the European Stationary Cycle (ESC) and the European Transient Cycle (ETC). Smoke opacity is measured through the European Load Response (ELR) test. Since Euro VI, emissions have been tested through the World Harmonized Stationary Cycle (WHSC) and the World Harmonized Transient Cycle (WHTC).
The Euro VI standards introduced off-cycle laboratory testing and on-road testing with portable emissions measurement systems (PEMS). The testing requirements for type-approval include:
- WHSC + WHTC test for diesel engines; WHTC test for positive ignition engines;
- Off-cycle emission (OCE) testing over the WNTE control area of the engine map;
- On-road PEMS vehicle test.
Additionally, the Euro VI regulation introduces in-service conformity (ISC) on-road PEMS testing. The testing is conducted over a mix of urban, rural, and motorway conditions. The exact trip composition depends on the vehicle category. ISC testing is required within 18 months of the first registration of an engine type in the EU, on any vehicle that has accumulated a minimum of 25,000 km. EU VI-E incorporates a cold start requirement, with emissions evaluations beginning at a lower temperature.
To evaluate compliance, the emissions are averaged using the moving averaging window (MAW) method. Under the MAW method, mass emissions are calculated for subsets of a complete data set, called windows. The window size is defined by the work, or CO2 emissions, over the window, which must be equal to those of the WHTC. The windows are deemed valid for compliance purposes if the following conditions are met:
- The window’s average power is above a certain threshold (see table 3 for reference);
- The coolant temperature is above a certain threshold (see Table 3 for reference);
- Regeneration of the aftertreatment system (e.g., the DPF) does not take place.
A vehicle is deemed compliant if the average emissions of at least 90% of all valid windows are below the ISC limit. The ISC limit is a function of the type-approval limit over the WHTC, multiplied by a conformity factor (CF).
The Euro VI provisions for ISC PEMS testing are phased-in over several implementation steps. The corresponding stages of the emission standards are referred to as Euro VI-A through Euro VI-E. Starting in Euro VI-E, PEMS testings must be carried out using a cold start, with emissions evaluations beginning at a lower temperature of 30°C, and a conformity factor of 1.63 is set for PN.
| Step | Implementation dates | ISC PEMS Requirements | ||||||
|---|---|---|---|---|---|---|---|---|
| New types | All vehicles | Last possible registration |
PEMS power threshold |
Cold start required in PEMS | Min. coolant temperature |
CF gaseous pollutants | CF PN | |
| A | Jan. 2013 | Jan. 2014 | Aug. 2015 | 20% of max. power | Nob | 70°C | 1.50 | – |
| B (CI) | Jan. 2013 | Jan. 2014 | Dec. 2016 | |||||
| B (PI) | Sept. 2014 | Sept. 2015 | Dec. 2016 | |||||
| C | Jan. 2016 | Jan. 2017 | Aug. 2019 | |||||
| D | Sept. 2018 | Sept. 2019 | Dec. 2021 | 10% of max. power | ||||
| E | Jan. 2021 | Jan. 2022 | – | Yesc | 30°C | 1.63a | ||
| Notes: (a) For PI engines and dual-fuel engines, the conformity factor for PN applies from 2023.01 for new types, and from 2024.01 for all new vehicles.
(b) evaluation starts when coolant temperature reaches 70°C (c) evaluation starts when coolant temperature reaches 30°C |
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Durability
Effective since October 2005 for new type approvals, and since October 2006 for all engine sales and registrations, manufacturers should demonstrate that engines comply with the emission limit values for useful life periods that depend on the vehicle category, as shown in the following table:
| Vehicle Category† | Period* | |
|---|---|---|
| Euro IV-V | Euro VI | |
| N1 and M2 | 100,000 km / 5 years | 160,000 km / 5 years |
| N2 N3 ≤ 16 ton M3 Class I, Class II, Class A, and Class B ≤ 7.5 ton |
200,000 km / 6 years | 300,000 km / 6 years |
| N3 > 16 ton M3 Class III, and Class B > 7.5 ton |
500,000 km / 7 years | 700,000 km / 7 years |
| † Mass designations (in metric tons) are the maximum technically permissible mass * km or year period, whichever is sooner |
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Effective October 2005 for new type approvals and October 2006 for all type approvals, type approvals also require confirmation of the correct operation of the emission control devices during the normal life of the vehicle under normal conditions of use, also known as “conformity of in-service vehicles properly maintained and used.”
Fuel quality
The Euro III and Euro IV standards were preceded by the introduction of more stringent fuel regulations that required a minimum diesel cetane number of 51 (in 2000), a maximum diesel sulfur content of 350 ppm (2000), 50 ppm (2005), and a maximum petrol (gasoline) sulfur content of 150 ppm (2000) and 50 ppm (2005). Ultralow-sulfur diesel and gasoline fuels (≤ 10 ppm S) became available in 2005 and were mandatory beginning in 2009.
On-board diagnostics (OBD)
Starting with Euro IV standards, on-board diagnostics (OBD) systems are mandated in all new heavy-duty vehicles. OBD systems are an important element of the emission control system that enables the identification of malfunctioning components. OBD systems monitor a certain set of components and pollutants at regular intervals, defined by the in-use performance ratio (IUPR). The OBD system only alerts of the presence of malfunctions that would cause emissions to exceed OBD threshold limits (OTL).
Euro VI standards expand the performance monitoring requirements to now include a wider set of components monitored, and stricter IUPR and OTLs provisions. These provisions are phased-in over several implementation steps:
| Step | NOx OTL (g/kWh) |
PM OTL (g/kWh) (CI & DF only) |
CO OTL (g/kWh) (PI only) |
IUPR | Reagent quality monitoring |
Additional OBD monitors |
|---|---|---|---|---|---|---|
| A | 1.5 | Performance monitoring | – | Phase-in | Phase-in | No |
| B (CI) | ||||||
| B (PI) | – | 7.5 | – | |||
| C | 1.2 | 0.025 | General (UNECE R49) |
General (UNECE R49) |
Yes (UNECE R49) |
|
| D | ||||||
| E |
Links
Regulatory Documents
1987 regulation, laying the framework for Euro standards:
Euro I/II standards:
Euro III/IV/V standards:
Directive 1999/96/EC
Directive 2005/55/EC (amended Euro IV and V)
Directive 2005/78/EC, implementing Directive
Euro VI:
Consolidated version of main act (including all amendments), Regulation (EC) No 595/2009
Consolidated version of implementing act (including all amendments), Regulation (EU) No 582/2011
