What You Need to Know About AQI: Understanding the Air Quality in Your Country

Understanding air quality in your country

The Air Quality Index (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.

understanding air quality India

The World Health Organization (WHO) has established guidelines for the six pollutants considered the most relevant for outdoor air quality. It is important to note these are guidelines, not legally enforced standards strictly speaking. Despite their accuracy, these values can be too technical for use by the general public.


Some countries also have their own Air Quality Index and calculation procedure. Specifically, in Canada, the AQI scale is starting from 1 – 10+. Meanwhile in the UK is between 0 to 10 and in China is between 0 to 300+. Furthermore, you may check the AQI index for several countries by clicking the country name: Canada, UK, European Union, Hong Kong, China, India, Mexico, Singapore.

In the United States, the Environmental Protection Agency (EPA) calculates the AQI by combining five major air pollutants regulated by the Clean Air Act: ground-level ozone, particle pollution (also known as particulate matter), carbon monoxide, sulphur dioxide, and nitrogen dioxide. Additionally, for each of these pollutants, the EPA has established national air quality standards to protect public health. Ground-level ozone and airborne particles are the two pollutants that pose the greatest threat to human health in this country.

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. Meanwhile, 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, consequently, the air quality is unhealthy-at first for certain sensitive groups of people, then for everyone as AQI values get higher.

The purpose of the AQI is to help you understand what local air quality means to your health. To make it easier in understanding the air quality index, there are six categories:


The EPA has assigned a specific colour to each AQI category to make it easier for people to understand quickly whether air pollution is reaching unhealthy levels in their communities. Indeed, each category corresponds to a different level of health concern. For example, orange means that conditions are "unhealthy for sensitive groups," while red means that conditions may be "unhealthy for everyone," and so on.

The six levels of AQI rankings and what they mean:

  • "Good" AQI is 0 to 50. At this level, the air quality is satisfactory, and air pollution poses little or no short-term risk.
  • "Moderate" AQI is 51 to 100. Air quality is acceptable; however, for some pollutants, there may be a moderate health concern for a very small number of people. For instance, people who are unusually sensitive to ozone may experience respiratory symptoms.
  • "Unhealthy for Sensitive Groups" AQI is 101 to 150. Although the general public is not likely to be affected at this AQI range, people with lung disease, older adults and children are at 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.
  • "Unhealthy" AQI is 151 to 200. Everyone may begin to experience some adverse health effects, and members of the sensitive groups may experience more serious effects.
  • "Very Unhealthy" AQI is 201 to 300. This would trigger a health alert signifying that everyone may experience more serious health effects.
  • "Hazardous" AQI is greater than 300. It precipitates health warnings of emergency conditions. Moreover, hazardous air would affect the entire population.

Air Matter providing real-time Air Quality Index

On their website as well as their apps, we can see AQI from more than 50 countries and choose specific places too. Not only that, but they also provide information about pollen that is very important to some people with pollen allergies. In addition, they also provide weather data, as well as protection recommendations and forecast.

If you have an air purifier or air monitoring devices, you also can connect with your own air purifier or air monitoring devices, then control the air purifier remotely, compare indoor air quality with outdoor and get health advice.

It is important to understanding air quality index in your area so that you are aware of when you need to protect your lungs.

Go check your city Air Quality Index in Air Matters, available on iOS and Google Apps, or check it here directly!

Understanding air quality