NOx is a toxic air pollutant from the exhaust of diesel-powered engines. It contributes to the formation of smog, ozone layer depletion and acid rain and is a threat to the environment.
 

NOx is a problem due to the growing number of diesel-powered trucks and passenger cars throughout the world.

 

To encourage car and truck manufacturers to find and implement NOx reducing solutions, a number of laws have been passed, both in the EU and in the US, establishing limits for NOx levels in exhaust.

The concentration of NOx in the air above major cities has been alarmingly high for many years and is still increasing.