What does the term "NOx" stand for in relation to vehicle emissions?

The term "NOx" stands for nitrogen oxides, which is a collective term for nitric oxide (NO) and nitrogen dioxide (NO2). These gases are significant pollutants that contribute to atmospheric issues such as smog and acid rain, as well as having harmful health effects. In the context of vehicle emissions, NOx is a byproduct of combustion processes at high temperatures, where nitrogen from the air reacts with oxygen. Understanding NOx is crucial for regulating emissions and implementing control technologies in vehicles to minimize their environmental impact.

Nitric oxide and nitrous oxide refer to specific compounds but do not encompass the broader category that NOx represents, which includes both nitric oxide and nitrogen dioxide. Non-oxide compounds do not pertain to nitrogen oxides at all, making them irrelevant in this context. Therefore, the choice of nitrogen oxides accurately captures the full scope of what NOx refers to in relation to vehicle emissions.