What is NOx? Why do we care?

• A. Because it's a pollutant. It is produced when nitrogen and oxygen combine in high temps.
• B. A fuel additive that prevents corrosion.
• C. A colorless gas used for inerting.
• D. A lubricant for pumps

Answer: (A)

NOx refers to nitrogen oxides, mainly nitric oxide (NO) and nitrogen dioxide (NO2). These pollutants form when nitrogen in the air reacts with oxygen during high-temperature combustion, such as inside engines, furnaces, or power plants. They don’t form much at ambient temperatures, but the high heat of burning fuels enables the reaction.

We care because NOx is a pollutant that affects air quality and health. It contributes to smog and the formation of ground-level ozone, irritates the lungs, and can worsen asthma and other respiratory conditions. It also plays a role in acid rain and environmental damage. For these reasons, industries limit NOx emissions and use control methods like optimizing combustion conditions, exhaust gas recirculation, selective catalytic reduction, and low-NOx burners.