Understanding the Air Quality Index

Air Quality Index (AQI) measures the air quality in ranges from 0 to 500.

The higher the level of air pollution, the higher the AQI.

Air Quality Index (AQI)

The AQI meter displays a couple of useful metrics. The first type of information shown is the air quality. This is represented by both a number, 0-300 and a corresponding color. The chart below describes the meaning of the numbers and their colors as they relate to the AQI. In the example above, the AQI rating is 112, orange, which is considered unhealthy for sensitive groups.

AQI

Good (green)

0-50

Air quality is satisfactory and air pollution causes little or no risk.

Moderate (yellow)

51-100

Air quality is acceptable; however, there may be a risk for some people, particularly those who are unusually sensitive to air pollution.

Unhealthy for Sensitive Groups (orange)

101-150

Members of sensitive groups may experience health effects. The general public is less likely to be affected.

Unhealthy (red)

151-200

Members of sensitive groups may experience health effects. The general public is less likely to be affected.

Very Unhealthy (purple)

201-300

Health alert: The risk of health effects is increased for everyone.

Hazardous (maroon)

301+

Health warning of emergency conditions; everyone is more likely to be affected.

Pollutants

The second metric on the AQI meter is the pollutant indicator, with the pollutant code displayed below the date and time. The chart below shows the pollutants.

03 — Ground-level ozone

The most at-risk group includes people with lung disease, children, older adults, people who are active outdoors, people with certain genetic variants, and people with limited intake of certain nutrients.

PM 2.5 — Particle matter

Particles that have diameters of 2.5 micrometers or less. Most at-risk groups include people with heart or lung disease, older adults, and children.

PM 10 — Particle matter

Particles that have diameters of 10 micrometers or less. Most at-risk groups include people with heart or lunch disease, older adults, and children.

CO — Carbon monoxide

The most at-risk group is people with heart disease.

S02 — Sulfur dioxide

Most at-risk groups include people with asthma, children, and older adults.

N02 — Nitrogen dioxide

Most at-risk groups include people with asthma, children, and older adults.