Nitrogen oxides (NOX) are different nitrogen gases: Nitric oxide (NO) y nitrogen dioxide (NO2). The term NOX refers to both gases combination because of the easy mutual conversion when oxygen is present.
From a formal aspect, nitrogen oxides are comprised of the following compounds: NO, NO2, N2O2, N2O4, N2O, N2O3, N2O5 and NO3, the latter being unstable.
All of them are contaminant gases, so NOX emissions must be treated to avoid their impact on the environment, such as:
Part of NOX emissions are caused by natural reasons (bacterial decomposition of organic nitrogen, wildfires, volcanic activity, storms, etc.). However, the most important production is anthropogenic: fossil fuels use and combustion engine vehicles exhaust.
Learn more about selective catalytic reduction of NOx in our blog.