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The AQI is an index 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. Ground-level ozone and airborne particles are the two pollutants that pose the greatest threat to human health.

The PM2.5 index describes the pollution level caused by "Fine particles," such as those found in smoke and haze, 2.5 micrometers in diameter and smaller. These particles can be directly emitted from sources such as forest fires, or they can form when gases emitted from power plants, industries and automobiles react in the air.

The Ozone index provides an indicator for Bad Ozone. In the Earth's lower atmosphere, near ground level, ozone is formed when pollutants emitted by cars, power plants, industrial boilers, refineries, chemical plants, and other sources react chemically in the presence of sunlight. Ozone at ground level is a harmful air pollutant.

How Does the AQI Work?

Think of the AQI as a yardstick 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 represents hazardous air quality.

An AQI value of 100 generally corresponds to the national air quality standard for the pollutant, which is the level EPA has set to protect public health. AQI values below 100 are generally thought of as satisfactory. When AQI values are above 100, air quality is considered to be unhealthy-at first for certain sensitive groups of people, then for everyone as AQI values get higher.

Understanding the AQI

The purpose of the AQI is to help you understand what local air quality means to your health. To make it easier to understand, the AQI is divided into six categories. Each category corresponds to a different level of health concern. The six levels of health concern and what they mean are:

index range
air quality
health concern
guidance
0-50
Good
Air quality is considered satisfactory, and air pollution poses little or no risk.
None.
51-100
Moderate
Air quality is acceptable; however, for some pollutants there may be a moderate health concern for a very small number of people. For example, people who are unusually sensitive to ozone may experience respiratory symptoms.
Unusually sensitive people should consider reducing prolonged or heavy exertion
101-150
Unhealthy for Sensitive Groups
Although general public is not likely to be affected at this AQI range, people with lung disease, older adults and children are at a greater risk from exposure to ozone, whereas persons with heart and lung disease, older adults and children are at greater risk from the presence of particles in the air.
People with heart or lung disease, older adults, and children should reduce prolonged or heavy exertion.
151-200
Unhealthy
Everyone may begin to experience some adverse health effects, and members of the sensitive groups may experience more serious effects.
People with heart or lung disease, older adults, and children should avoid prolonged or heavy exertion. Everyone else should reduce prolonged or heavy exertion.
201-300
Very Unhealthy
This would trigger a health alert signifying that everyone may experience more serious health effects.
People with heart or lung disease, older adults, and children should avoid all physical activity outdoors. Everyone else should avoid prolonged or heavy exertion.
301-500
Hazardous
This would trigger a health warnings of emergency conditions. The entire population is more likely to be affected.
  

 

Reference:AirNOW
above guidance is provided for reference only, use at your own risk
 
 
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