Air Quality Index (AQI)

What is the Air Quality Index?

The Air Quality Index (AQI) is a tool for reporting daily air quality. It tells you how clean or polluted your air is and what associated health effects might be a concern for you. The AQI focuses on health effects you may experience within a few hours or days after breathing polluted air. It takes all the monitored pollutants and relates them to a single-scale value to indicate air quality. See the AQI guide below for details.

• AQI Guide for Ozone and Particle Pollution

How does the AQI work?

Think of the AQI as a scale that runs from 0 to 500. The higher the AQI value, the greater the level of air pollution and the greater the health concern. For example, an AQI value of 50 represents good air quality with little potential to affect public health, while an AQI value over 300 indicates hazardous air quality. Florida rarely has AQI values greater than 100 and has never officially had a value greater than 200.

An AQI value of 100 generally corresponds to the national air quality standard for the pollutant, which is the level the U.S. Environmental Protection Agency (EPA) has set to protect public health. AQI values below 100 are generally thought of as satisfactory. AQI values near or just above 100 indicate air quality is considered to be unhealthy for certain sensitive groups of people. Higher AQI values indicate the air quality is unhealthy for everyone. For more information on the AQI visit EPA's AIRNow website.

What is the federal standard?

The federal Clean Air Act directs EPA to establish a health-based standard for an acceptable concentration level of several pollutants, including ozone and particle pollution in the atmosphere. This site reports the continuous data concentrations for these two pollutants.

The new federal standard for ozone has been established at a level equivalent to 70 parts per billion averaged over any eight-hour period. An area will be considered in violation (not meeting the standard) if the average of the annual fourth highest maximum daily eight-hour average ozone concentration at any ozone monitor for a three-year period exceeds 70 parts per billion.

The particulate pollution posted on this page is fine particle concentrations. The standard for fine particles or Particulate Matter 2.5 (PM_2.5), has two parts: One is annual and one is daily. The level of the annual standard is 9.0 µg/m³ annual arithmetic mean and 35 µg/m³ for a 24-hour average. The annual standard is violated if the three-year average is above 9.0 µg/m³. The 24-hour standard is violated if the three-year average of the annual 98th percentile of daily averages at a site is above 35 µg/m³.

Air Quality Guide for Ozone and Particle Pollution

Air Quality Category	Health Impacts	Air Quality Index	Ozone Concentration (ppm) 1	Ozone Concentration (ppb) 2	Particle Pollution Concentration (µg/m3) 3
Good Image	No health impacts are expected when air quality is in this range.	0 to 50	0.0 to 0.054	0 to 54	0.0 to 9.0
Moderate Image	Ozone: Unusually sensitive people should consider reducing prolonged or heavy exertion outdoors. Particle Pollution: Unusually sensitive people should consider reducing prolonged or heavy exertion.	51 to 100	0.055 to 0.070	55 to 70	9.1 to 35.4
Unhealthy for Sensitive Groups Image	Ozone: Active children and adults, and people with respiratory disease should limit prolonged outdoor exertion. Particle Pollution: People with heart or lung disease, older adults and children should avoid prolonged or heavy exertion.	101 to 150	0.071 to 0.085	71 to 85	35.5 to 55.4
Unhealthy Image	Ozone: Active children and adults, and people with respiratory disease, such as asthma, should avoid all outdoor exertion: everyone else, especially children, should limit outdoor exertion. Particle Pollution: People with heart or lung disease, older adults and children should avoid prolonged or heavy exertion. Everyone else should reduce prolonged or heavy exertion.	151 to 200	0.086 to 0.105	86 to 105	55.5 to 125.4
Very Unhealthy Image	Ozone: Active children and adults, and people with respiratory disease, such as asthma, should avoid all outdoor exertion: everyone else, especially children, should limit outdoor exertion. Particle Pollution: People with heart or lung disease, older adults and children should avoid all physical activity outdoors. Everyone else should avoid prolonged or heavy exertion.	201 to 300	0.106 to 0.200	106 to 200	125.5 to 225.4

¹ 8-hour average in parts per million 

² 8-hour average in parts per billion

³ 24-hour daily average