Why is air quality measured?

Many organisations around the world measure air quality in different ways.  For example, NASA uses satellites orbiting the earth to take pictures of particles and gases or specific polluting events like wildfires or volcanic eruptions.

These records allow us to track the changes in air quality and predict trends and problems that may occur.  For example, tracking the direction of plumes of volcanic ash after an eruption allows planes to change course and can save lives on the ground by evacuating people from areas that may be at risk