Air Quality Index (AQI), a multi-pollutant assessment tool, is a useful way to quantify air quality. To better understand the AQI we will look at its key components as well as the pollutants measured. Visit our website and learn more about what is air quality index.

Major Air Pollutants Included In the AQI

Particulate Mater (PM2.5 & PM10): PM2.5 are fine particles of a diameter less than 2.5 mm, whereas PM10 include particles smaller than 10 mm. These particles are able to penetrate the respiratory system and cause serious health problems.

Ground Level Ozone (O3) – Ground level ozone or “bad ozone” is created when pollution from cars and other industrial sources reacts in sunlight. High levels of ozone can lead to respiratory problems and irritation.

Carbon Monoxide (CO), a gas without color or odor, is created by incomplete combustion. The gas is toxic and interferes with oxygen transportation in the body.

Sulfur Dioxide – Sulfur Dioxide gas is a byproduct of burning sulfur-containing fossil fuels like coal and oil. A short-term increase in SO2 can affect the respiratory tract and aggravate respiratory diseases.

Nitrogen Dioxide(NO2) Nitrogen Dioxide produces a brownish red gas, which is produced during combustion in engines and power stations. It can be irritating and cause ground level ozone.

Calculating the AQI

Each of these pollutant scales is based a concentration level and on established standards. The value of the highest AQI rating among these pollutants will be used to calculate an overall AQI in a certain location. It ensures the AQI reflects pollutant levels that are most harmful to health at any particular time.

The AQI and Individual Pollutants

As previously mentioned, for every pollutant on the AQI Scale, there are different categories that indicate the level of risk to human health. Categories help determine the risk associated with pollutants. As an example, if PM2.5 falls under the category of “Unhealthy Groups”, this indicates that fine particulate material is a potential risk for individuals with sensitive skin.


The AQI allows for a thorough assessment of air pollution by evaluating multiple air contaminants, each having its own implications on human health. The AQI is a comprehensive assessment of air quality that takes into account multiple pollutants, each with its own impact on health.