As of the 1st Jan 2005, new vehicles sold in Europe have needed to comply with the Euro 4 Emissions standard, this stage of the Euro's standard requires harmful emissions to be halved from the previous Euro 3 requirement.

In order to meet the new standards, all heavy good vehicles need to reduce the amount of NOx (Nitrous Oxides) they emit.

Euro 5 is effective as of October 2009. The new limits outlined in Euro 5 are even more stringent than before, in fact almost half of the previous standard.

Vehicle manufacturers are opting for SCR (Selective Catalytic Reduction) as the preferred technology to meet the demands set out by Euro 5. This involves incorporating the urea into an aqueous solution called AdBlue. The alternative is EGR (Exhaust Gas Recirculation) but this technology has its limits and at present will not be able to meet the demands of Euro 6 due in 2012

There are a number of advantages with SCR technology as around 85% of the nitrous oxide is converted into water vapour and nitrogen. (the air we all breath is approximately 74% nitrogen). Fuel savings of approximately 6% can be achieved using the SCR method. This has encouraged many of the leading manufacturers to concentrate their efforts on developing SCR vehicles in their range. With fuel pump prices now at a record high, support for SCR is growing fast.

Concern has been identified at the outset though as AdBlue is highly susceptible to contamination unless handled correctly, which has led to some dispute surrounding the creation of new ISO standards, who should be involved and how should they be implemented.

At present the AdBlue solution is produced in Europe and shipped to the UK, although there are plans to create production plants in the UK none are available to date.

Sceptics are using these considerations to argue the long term suitability of the AdBlue concept in the UK's Market.

However unless an alternative cleaner fuel solution is made available before October next year all modern fleet operators will have to adopt this new technology sooner or later.

The transport industry are encouraging the authorities to develop new standards to help guide consumers through this new technology.