Many modern technologies and methods have been developed to reduce amount of NO x emissions since these gases readily react with common organic chemicals to form variety of toxic products like nitric acid vapors and nitro arenes. Some of the control techniques are:

• Exhaust Gas Recirculation(EGR) is being widely used in many vehicles.

• Selective Catalytic Reduction (SCR) and Selective Non – Catalytic Reduction (SNCR) are now being used in diesel trucks and cars.

• Water injection technology, in which water is introduced into the combustion chamber.

• Catalytic Converters

• Lean $NO_{x}$ traps (LNT) are $NO_{x}$ adsorber catalysts

• Three way catalysts (TWC) which are basically palladium-rhodium or tri-metal formulations to reduce $NO_{x}$ to nitrogen.