Air Quality Index

You can’t always see pollution. The visual appearance of an inversion is much the same regardless of air quality. This is one reason the DEQ maintains an Air Monitoring Center to determine air quality conditions and the Division of Air Quality (DAQ) scientists use the information from these monitors to assess daily air quality, issue health advisories and announce voluntary and mandatory actions to reduce emissions. Advisories are based on the Air Quality Index (AQI).

Being fully informed about air quality will allow you to make choices that protect your health and reduce your emissions when air quality is poor. Accessing this information is quick and easy. Here’s how to get started:

Adjust Your Activities

The EPA has published a guide to particle pollution that provides useful information about the health effects of particulates and how to avoid exposure.Use the AQI forecasts to plan your activity level on poor air quality days.

If the day’s level is orange or worse, modify your plans. Avoid prolonged or heavy exertion outdoors, particularly in high traffic areas. Have children play indoors during recess. Use filters and air cleaners that are designed to reduce indoor particulate levels.

Index Levels

The DAQ provides information to residents concerned about the health impacts of particulate levels through the Air Quality Index.


The AQI is a color-coded tool that helps residents understand the health impacts of local air quality. It is divided into six categories that correspond to different levels of health impacts based on EPA numerical values for five major pollutants regulated by the Clean Air Act: ground-level ozone, particulate matter, carbon monoxide, sulfur dioxide, and nitrogen dioxide.For each of these pollutants, the EPA has established national air quality standards to protect public health. The color codes correspond to air quality conditions. Green is good, yellow is moderate, orange is unhealthy for sensitive groups, red is unhealthy for all groups. Purple and maroon signal very unhealthy and hazardous air quality conditions, respectively.

Watch for Division of Air Quality Action Alerts

The DAQ issues action alerts when pollution is approaching unhealthy levels. These alerts proactively notify residents before pollution build-up so they can begin to reduce their emissions. When pollution levels reach 15 µg/m3 for PM2.5, DAQ issues a ‘yellow’ or voluntary action day, urging Utah residents to drive less and take other pollution reduction measures. At 25 µg/m3, 10 µg/m3 below the EPA health standard, DAQ issues a “red” or mandatory advisory prohibiting burning of wood and coal stoves or fireplaces.