Legislation and Technology

In order to reduce air pollution, European legislation is setting tighter limits on emissions from Diesel Vehicles. Two of the main pollutants are Oxides of Nitrogen (NOx) and Particulate Matter (PM).

In 1990, the first of these Standards, Euro 0, came into effect with NOx limits of 14.4 and PM limits of 1.1, both measured in g/kwh. The current Euro III standard, effective from 2001, has reduced these limits to 5 and 0.1 respectively.

The imminent Euro IV standard, due for implementation from 1st October 2006, cuts PM by a further 80% to 0.02g/kwh and NOx to 3.5g/kwh. In 2009 Euro V standards become compulsory, with no further reduction in PM levels but a further decrease in NOx levels to 2g/kwh. This will mean that a single Euro 0 vehicle emits the same amount of PM as 55 Euro IV’s.



These drastic reductions impose serious technological challenges for Engine manufacturers, since reducing NOx in the combustion chamber increases particulates and vice versa.

Engine Manufacturers have therefore adopted two main technologies to cope with reductions of pollution levels. The first is called Exhaust Gas Recirculation or EGR. This involves cooling a percentage of the exhaust gas and feeding it back into the combustion chamber to burn at a lower temperature, thus reducing NOx formation. The PM pollutants are then reduced in the exhaust system via a particulate filter.

Although this system requires no additive, limitations on chassis space mean that larger engines cannot use the system. Due also to the burning of carbon-rich exhaust gases, oil drain intervals will be shorter.

The second is an after treatment system called Selective Catalytic Reduction or SCR. In this system the PM emissions are controlled within the combustion chamber and NOx is reduced in the exhaust gases by using a reagent called AdBlue. This is injected directly into the exhaust gas and via a chemical reaction in a Catalyst converts pollutants such as NOx into environmentally friendly Nitrogen and Water. The advantage of this system is that it offers fuel economy benefits and can be adapted to cope with Euro V emission levels very easily. The AdBlue is dosed typically at 4-5% by volume of the rate of diesel for Euro IV, and 5-6% for Euro V standards.

AdBlue FAQs:

What is AdBlue?

AdBlue is a non-toxic aqueous urea solution used to chemically reduce NOx-emission from heavy-duty diesel powered vehicles. AdBlue is neither explosive nor harmful to the environment and is classified under the minimum-risk category of transportable fluids. AdBlue as supplied through Yara’s Air1® is guaranteed to meet the DIN V 70070 standard and complies with ISO and CEFIC regulations to safeguard the correct functioning of your vehicle’s SCR system.

What are Euro IV and Euro V?

Euro IV and Euro V are standards set by the EU, to control emission of pollutants from heavy-duty vehicles. NOx, particulate matter (PM), hydrocarbons (HC) and carbon monoxide (CO) are the components regulated. The Euro IV standard will be implemented from Oct. 2005 to Oct. 2006 and Euro V from Oct. 2008 to Oct. 2009. Emission limits for NOx is 3.5 g/kWh in Euro IV and 2.0 g/kWh in EuroV.

What is SCR technology?

SCR stands for Selective Catalytic Reduction which indicates that only NOx and no other oxidised species (thus selectively) is chemically reduced to elemental nitrogen and water on a purpose-built catalyst. Most major European heavy-duty vehicles manufacturers have decided to use this technology to meet the new emission legislation. The main components of the SCR system are the SCR catalyst, the AdBlue injection unit, the AdBlue tank and the AdBlue dosing control unit. The harmful NOx molecules in the exhaust are converted to harmless nitrogen and water. This happens when NOx reacts inside the catalyst with the ammonia in the AdBlue, is injected into the exhaust pipe upstream of the catalyst where its urea molecules react with heat and water to form the ammonia needed.

What is Air1®?

Air1 is a brand developed by Yara to ensure you a secured supply of the high-quality AdBlue needed in your SCR system. Yara has formed a partnership with Europe’s largest chemical distributor, Brenntag, to ensure the supply of AdBlue through the Air1 concept all across Europe.

What advantages does Air1®offer?

Air1® offers AdBlue supply from Yara, Europe’s largest producer of urea, the active ingredient in AdBlue. We can ensure high security of supply from several production plants.

How much does AdBlue cost?

The price of AdBlue may vary according to quantities delivered, but it is estimated to be roughly half the gross price of diesel per litre. Reduced fuel consumption of SCR equipped vehicles is expected to more than compensate for the cost of AdBlue.

How much AdBlue will I need?

It is expected that the average AdBlue consumption will be about 4% by volume of diesel consumption for Euro IV and about 6% for Euro V. Roughly this amounts to an AdBlue consumption of 1.7 litres per 100 km of highway driving.

Make an Enquiry:

+44 (0) 1744 813535

or complete the following short form:

Your Name (required)

Your Email (required)


Your Message