In a bid to improve air quality and lower air pollution, the European emission standards were first implemented in 1992. Since then, several iterations have been introduced – ranging from Euro 1 to Euro 6 – that directly target pollutants found in vehicle exhaust emissions, such as hydrocarbons and particulate matter (PM). These standards, although initially established by the European Union, are still in effect across the UK even after Brexit. They have even helped form new policies, such as the rollout of ULEZ zones in the UK. As a result, all new vehicles sold in the UK are obligated to meet these environmental standards. In this article, we’ll provide a comprehensive guide for Euro 1 to Euro 6.

The Beginnings: Euro 1 (1992)

Introduced in 1992, the Euro 1 standard marked the first EU-wide vehicle emission standards. This regulation primarily focused on limiting carbon monoxide (CO) and hydrocarbons (HC) from petrol engines, and it set a CO limit of 2.72 grams per kilometre for cars. Diesel vehicles under Euro 1 were required to meet a PM limit of 0.97 g/km, which was quite lenient compared to later standards.
A few of the main takeaways from the Euro 1 rollout was the introduction of catalytic converters – which are still a target for thieves – and bold new targets for emissions. This would eventually pave the way for a host of new policies and initiatives geared towards lowering different emissions beyond CO.

Euro 2 (1997): Tightening Limits

By 1997, Euro 2 standards reduced permissible levels of key pollutants for new cars sold in the EU. For petrol engines, the CO limit was reduced to 1 g/km, and for diesel, the focus remained on reducing PM emissions alongside tighter limits on CO and HC.
Euro 2’s fine-tuning of emissions standards also meant that unburned Nitrogen Oxide (NOx) was being graded alongside HC. The target at this time was 0.7g/km for both NOx and HC. To do this, new testing procedures were also brought in. These tests were more thorough and put significant pressure on car manufacturers to more eco-friendly design engines.

Euro 3 (2001) and Euro 4 (2006): The Shift Towards Lower Emissions

Euro 3 and Euro 4 standards, introduced in 2001 and 2006 respectively, brought significant reductions in emissions. Euro 3 slashed the allowable levels of HC and NOx for both petrol and diesel engines. For diesel, NOx limits were set to 0.5g/km, CO was 0.66h/km, PM was 0.05g/km. HC and NOx combined had a limit of 0.56g/km. Along with these changes, Euro 3 split the limits for HC and NOx for diesel vehicles and did not allow trucks or lorries to warm up before testing.
Euro 4, when rolled out in 2005, pushed these emission standards even further. The focus was on cleaning up emissions with a focus on NOx and PM. The new emissions limits for Euro 4 diesel vehicles included:
• NOx – 0.25g/km
• CO – 0.5g/km
• PM – 0.025g/km
• HC and NOx – 0.3g/km

Euro 5 (20011): Addressing Diesel Particulates

Recognising the increasing concern about air quality, particularly regarding diesel vehicles, Euro 5 targeted a substantial cut in PM emissions from diesel engines. One of the defining changes with Euro 5 was the rollout of diesel particulate filters (DPF) which captured 99 % of all PM in diesel vehicles. This innovation was instrumental in bringing new trucks and lorries into compliance with the lower emission standards. The new limits at this point included:
• NOx – 0.18g/km
• CO – 0.5g/km
• PM – 0.005g/km
• HC and NOx – 0.23g/km

Euro 6 (2015): The Current Standard

The latest in the series, Euro 6, was rolled out in 2015 and places much stricter limits on diesel emissions, particularly for NOx (0.08 g/km compared to 0.18 g/km in Euro 5). For petrol vehicles, the NOx limit was set at 0.06 g/km. This standard represents the toughest yet and includes limits for several other pollutants as well. The current standards for emissions are:
• NOx – 0.08g/km
• CO – 0.5g/km
• PM – 0.005g/km
• HC and NOx – 0.17g/km
A major reason for this change was the various studies linking NOx to respiratory issues in individuals. This prompted manufacturers to implement Selective Catalytic Reduction (SCR) technology into new vehicle models. This innovation injected a chemical into a vehicle’s catalyst and through the exhaust. This chemical could convert NOx into Nitrogen and water, greatly reducing emissions.
Another new technology that emerged around this time was specifically for lorries and was known as Exhaust Gas Recirculation. This allows the ECU in the vehicle computer to mix intake air with exhaust gas to lower the temperature it burns.

Emissions Standards are Bringing Us Closer to a Cleaner Future

The Euro standards have been instrumental in reducing vehicle emissions across the UK and Europe. Each progression brings us closer to cleaner, more sustainable transportation options. As the UK continues to focus on reducing vehicle emissions further, understanding these standards helps consumers make informed decisions about their vehicle purchases and environmental impact. Moving forward, we can expect continued innovations in vehicle technology and further tightening of emission standards as part of global efforts to combat air pollution and climate change.
If you have any questions about the latest Euro 6 emissions standards, or would like assistance in making your truck or lorry compliant with the latest standards, please contact our friendly team at James Hart Chorley Ltd today.