Quick Scoop: What is NOx emissions?

NOx emissions are releases of nitrogen oxides into the air, mainly nitric oxide (NO) and nitrogen dioxide (NO2). These gases are common air pollutants formed during combustion, especially in vehicles, power plants, boilers, and other high-temperature industrial processes.

Why it matters

NOx emissions contribute to smog, ground-level ozone, acid rain, and respiratory health problems such as worsened asthma and reduced lung function. They can also damage vegetation, ecosystems, materials, and buildings.

Common sources

• Road transport, especially engines.

• Shipping and other fuel-burning transport.

• Power generation and boilers.

• Industrial processes with very high temperatures.

Simple example

When fuel burns at high temperature in a car engine, nitrogen and oxygen in the air can react and form NO and NO2. Together, those pollutants are counted as NOx.

In one sentence

NOx emissions are harmful nitrogen-oxide pollutants from combustion that affect air quality, health, and the environment.

Bottom line: NOx is short for nitrogen oxides, and reducing it is important because it helps cut smog, ozone, acid rain, and breathing-related harm.

[9][3][1]