Blue Air is an aqueous urea solution used with the Selective Catalytic Reduction technology (SCR) of heavy-duty diesel vehicles to reduce emissions of oxides of nitrogen (NOx) from the exhaust system. 

Blue Air is a non-toxic aqueous 32.5% urea solution used to chemically reduce NOx emissions from heavyduty diesel powered vehicles. It is not a dangerous good, nor harmful to the environment, and is classified in the minimum-risk category of transportable fluids. Blue Air can simply be washed off with water should it be spilled on an operator’s hand.

Blue Air is neither a fuel, nor a fuel additive and needs to be used in a dedicated tank on the heavy-duty vehicle. It is replenished in a similar way to refueling diesel (about 4-5% by volume of diesel consumption for ADR 80/01 and about 5-6% for ADR 80/02).

There are different vehicle emission standards around the world, setting specific emission limits for the four main pollutants: Oxides of Nitrogen (NOx), Particulate Matter (PM), Carbon Monoxide (CO), and Hydrocarbons (HC). The use of SCR and Blue Air technology addresses the NOx component of these standards, and commenced with the introduction of Euro IV.