The Air Quality Index (AQI) tells you how polluted or clean your air is. Major cities in the world monitor the AQI on a daily basis. In highly polluted areas, you can find the determination of the AQI on a continuous basis.
The focus of the Air Quality Index
The AQI focuses on the health problems you experience on breathing the polluted air.
The environmental protection agencies calculate the Air Quality Index for five major air pollutants, ground-level ozone, particulate matter, sulphur dioxide, carbon monoxide, and nitrogen dioxide. Each of these five pollutants has their air quality standards.
How does the AQI work?
AQI works on a range of 0 to 500. The higher the value of AQI, the higher is the level of pollution. Understanding the AQI is easy because the agencies use colours to symbolise the air quality conditions.
The following table will help you understand the AQI better
| Air Quality Index | Levels of Health Concern | Colour indication |
| 0 to 50 | Good | Green |
| 51 to 100 | Moderate | Yellow |
| 101 to 150 | Unhealthy for Sensitive Groups | Orange |
| 151 to 200 | Unhealthy | Red |
| 201 to 300 | Very Unhealthy | Purple |
| 301 to 500 | Hazardous | Maroon |
Air Quality Index readings explained
0 to 50 – The air quality is excellent and does not pose any risk to your health. The green colour indicates safety.
51 to 100 – It is a moderate range indicated by the yellow colour.
101 to 150 – An AQI in the field of 101 to 150 shows that the quality of air is not healthy for people belonging to the sensitive category like children, pregnant women, senior citizen, and those suffering from vulnerable diseases.
151 to 200 – People begin to experience health problems when the AQI is in the range of 151 to 200
201 to 300 – The purple colour is an indication of poor quality air. An AQI in the range of 201 to 300 triggers a severe health alert.
Greater than 300 – AQI in this range can affect the entire population. It signifies an emergency condition.
Now, you know how the Air Quality Index works.
You can check Real Time World Air Quality here.