What is the air quality index? [Video]

NORFOLK, Va. — Air quality can become an issue when wildfires spark across the U.S. and Canada or when densely populated areas use a lot of fossil fuels.

Let’s talk about how scientists measure air quality. The air quality index measures the amount of pollutants that are present in the air. It specifically takes into account these five pollutants: 

The air quality index is measured on a scale of zero to 500. The higher the number, the worse the air quality is. Any number 50 or under is considered “good” air quality.

The air quality can become worse when wildfire smoke spreads from the source of the fire to other parts of the continent. Additionally, when the sun heats the …