Thursday brings an air quality warning to Chicago. The air quality index is in the 101-150 range, an orange warning for ozone indicating the air quality conditions are Unhealthy for Sensitive Groups.
But what exactly does this mean? How might you change your day to take account of the warning?
What is the Air Quality Index (AQI)?
The AQI is an index for reporting daily air quality, indicating how clean or how unhealthy the air is. It is based on four major pollutants: ground level ozone, particle pollution, carbon monoxide, and sulfur dioxide. The AQI runs from zero to 500, with a value of 100 representing the national air quality standard for each of the pollutants. Values of 100 or below are considered satisfactory; at values over 100, the air is considered to be increasingly unhealthy.
What do the AQI values mean?
The AQI is divided into six levels of health concerns:
- AQI 0 to 50 = air quality Good – represented by the color green
- AQI 51 to 100 = air quality Moderate – represented by the color yellow
- AQI 101 to 150 = air quality Unhealthy for Sensitive Groups – represented by the color orange
- AQI 151 to 200 = air quality Unhealthy – represented by the color red
- AQI 201 to 300 = air quality Very Unhealthy – represented by the color purple
- AQI 301 to 500 = air quality Hazardous – represented by the color maroon
What is meant by Unhealthy for Sensitive Groups?
Unhealthy here means certain groups may experience health effects from the air quality, but the general public is not likely to be affected. The groups depend on the type of pollution:
- Ozone: Individuals with lung disease, children, older adults, and people who are active outdoors are considered sensitive and therefore at greater risk.
- Particle pollution: People with heart or lung disease, older adults (starting at mid-40s for men and mid-50s for women), and children are considered sensitive and therefore at greater risk.
I’m not in a sensitive group, so when am I affected?
- At Unhealthy (AQI 151-200), everyone may begin to experience health effects from the pollution.
- At Very Unhealthy (AQI 201-300), a health alert is triggered, meaning everyone may experience more serious health effects.
- Hazardous (AQI 301-500) indicates emergency health conditions. The entire population is more likely to be affected by serious health effects.
How can I find the forecasted AQI?
The EPA AIRNow web site provides national air quality information, with links to detailed state and local air quality sites. You can access the Chicago Air Quality information here, and Illinois information here.
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