Learn About The AQI
If you notice pollution or smog on the horizon, you might think that your town is having a bad air quality day. In order to accurately measure just how clean or dirty our air is requires more than just a visual assessment. Instead, something called the Air Quality Index, or AQI, is used to measure and report the daily air quality. In addition to letting people know how healthy or hazardous the outside air is, the AQI also informs citizens what types of health issues they may experience after being exposed to unhealthy air.
In general, the Environmental Protection Agency calculates the AQI for five major sources of air pollution – all of which are regulated by the Clean Air Act. These are: ground-level ozone, particulate pollution, sulfur dioxide, nitrogen dioxide and carbon monoxide. Of these five, ground-level ozone and airborne particles are the biggest problem in terms of their impact on our health. To understand how the AQI works, envision a really long number line that goes from zero to 500. The higher an AQI value is, the more pollution the air contains and the more hazardous it is to our health.
To help make the AQI as visual and easy to understand as possible, the different ranges of numbers have also been given their own colors; for example when the AQI is in the zero to 50 range, it means that air quality is good, which is symbolized by the color green. An AQI that is in the 51 to 100 range indicates a “moderate” level of health concern, and it’s represented by the color yellow. On days when the air is a lot dirtier and filled with some or all of the five contaminants, the AQI would be in the “red” range of 151 to 200.
The absolute highest it can go is 301 to 500; on these days the air would be truly hazardous to health and it would be represented by the color maroon. Each category also corresponds to a different amount of concern for people who are breathing in the outside air. For example, a “moderate” AQI of 51 to 100 means that while the air quality is acceptable for most people, people who are especially sensitive to ozone might experience some breathing issues. By the time the AQI hits 151 and above, nearly everyone who breathes the air can expect to experience health issues, especially those with respiratory issues.