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Air Quality

In emergency situations, air particulates and ozone pollution levels can rise and pose challenges to those with respiratory issues or allergies. The Arizona Department of Environmental Quality monitors air quality issues and reports them on its website at as well as through . You may also want to tune in to your local radio news station. In the event of an air quality situation, follow authority guidelines for limiting time outside.

Measuring the Air Quality Index

When we see that air quality is “good” or “unhealthy”, those public health categories are derived from the Air Quality Index (AQI).

  • Ground-level ozone

  • Carbon monoxide

  • Sulfur dioxide

  • Particle pollution, also known as particulate matter

  • Nitrogen dioxide

Some countries have a slightly different way of calculating their scores. For example, India also measures levels of ammonia and lead in the air. To make these readings more accessible, the AQI has a scoring system that runs from 0 to 500, using data collected from air monitoring stations in cities around the world. Scores below 50 are considered good, with very little impact to human health. The higher the score gets, the worse the air quality is. To make communicating potential health risks to the public even easier, ranges of scores have been organized into descriptive categories.

AQI Basics for Ozone and Particle Pollution
Daily AQI Color Levels of Concern Values of Index Description of Air Quality
Green Good 0 to 50 Air quality is satisfactory, and air pollution poses little or no risk.
Yellow Moderate 51 to 100 Air quality is acceptable. However, there may be a risk for some people, particularly those who are unusually sensitive to air pollution.
Orange Unhealthy for Sensitive Groups 101 to 150 Members of sensitive groups may experience health effects. The general public is less likely to be affected.
Red Unhealthy 151 to 200 Some members of the general public may experience health effects; members of sensitive groups may experience more serious health effects.
Purple Very Unhealthy 201 to 300 Health alert: The risk of health effects is increased for everyone.
Maroon Hazardous 301 and higher Health warning of emergency conditions: everyone is more likely to be affected.