What Is the AQI?

AQI LogoThe EPA and your State environmental agency measure pollution in the air. Then they use the Air Quality Index, or AQI, to tell the people about the air. An index can be a quick way to tell people how good or bad something is. The AQI uses colors, andnumbers, andwords to tell you about the air.

AQI Colors

These are the AQI colors. Each day the AQI is one of these colors. The colors tell you how healthy the air is to breathe that day. The colors go from Green to Yellow to Orange to Red to Purple to Maroon, each color telling you that the air is less clean than the color before. Green is the best air quality. When the AQI is green,the air is clean!

We see a lot of Yellow, Orange, and Red AQI colors in the summer when air quality often isn't at its best. Purple and Maroon are the worst air quality! Luckily we hardly ever see the AQI get to Purple. Because of people working to clean up the air, the AQI has not reached Maroon in many years! This is why Maroon is usually not shown with the AQI.

AQI Numbers

An index with numbers can be a quick way to tell people how good or bad something is. For example, you might say your school lunch is a 1 (very good) or a 5 (yucky). The Air Quality Index uses numbers from 0 to 500. These numbers are used to decide the AQI color. On days measuring less than 100, the air is clean. If the air is dirtier, the numbers get bigger. On days measuring more than 100, the air can be bad for you to breathe.

Here is how the AQI numbers match up with the AQI colors:

AQI Numbers Colors
0 to 50 Green
51 to 100 Yellow
101 to 150 Orange
151 to 200 Red
201 to 300 Purple
301 to 500 Maroon

Where is the AQI?

You can find the AQI in several places. If you have a computer connected to the Internet, go to www.airnow.gov. Type in your zip code or city to display a dial with the AQI for your area. Or type in a state to display a chart with a list of cities. The AQI for many, but not all, large cities can be found there. Look for your city and you will see if the air in your city today is clean or not.

You can find the AQI in the newspaper, often in the weather section. Sometimes the weatherperson on TV or the radio will talk about the AQI for today and may also tell you what tomorrow's AQI will be.

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