There are several AQI systems across different countries and regions. Each system uses its own hazard index, contamination concentration, and data measurement time. In this regard, it is quite difficult for an ordinary user to navigate between the systems of different countries.  In this article we explain the Air Quality Score you see on Atmotube's app and other Air Quality Indices exist in different countries.

Atmotube's AQS

Since there is no unified air quality measurement system for the whole world, AtmoTech’s team has developed their own Air Quality Score.

Our Air Quality Score, 'AQS', was developed based on academic research, National AQIs and WHO recommendations. AQS scores air quality on a scale from 0 (severely polluted air) to 100 (very clean).

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Atmotube’s AQS is calculated based on concentrations of VOCs (volatile organic compounds)  such as formaldehyde, tetrachloroethylene, acetone, propylene and particulate matter, i.e. PM1, PM2.5, and PM10.

https://help.atmotube.com/faq/2-vocs/

https://help.atmotube.com/faq/6-pm-standards/

Air is good (81-100)

Air quality is considered satisfactory, and air pollution poses little or no risk.

Air is moderate (61-80)

Air quality is acceptable; however, some pollutants can cause moderate health concerns for a very small number of people who are unusually sensitive to air pollution.

Air is polluted (41-60)

Members of sensitive groups may experience health effects. Most people are unlikely to be affected.

Air is very polluted (21-40)

Everyone may begin to experience health effects; for members of sensitive groups health effects may be more serious.

Air is severely polluted (0-20)

Health alert: everyone may experience more serious health effects. Everyone should avoid all outdoor exertion.

United States (AQI)

The United States Environmental Protection Agency (EPA) has developed theAir Quality Index, or AQI that ranges from 0 to 500. The AQI is divided into six categories varying by severity of health concern. An AQI value over 300 represents hazardous air quality and below 50 the air quality is good. The American system is based on the measurement of five major pollutants:

  • ground-level ozone (O3)
  • particle pollution (PM2.5, PM10)
  • carbon monoxide (CO)
  • sulfur dioxide (SO2)
  • nitrogen dioxide (NO2)

– and converts their concentrations into a separate AQI for each pollutant. The highest AQI is reported as a common AQI for this area. More detailed information on how AQI is calculated can be found in the Technical Assistance Document at AirNow,


Canada (AQHI)

The Air Quality Health Index (AQHI) is an aggregated measurement system used in Canada to define air quality based on its impact on people’s health. The AQHI ranged between 1 to 10+. The AQHI index values are grouped into health risk categories as shown below.

The AQHI is based on scientific research conducted by Health Canada to identify major pollutants harming people’s health. These pollutants are:

  • ground-level ozone (O3)
  • PM2.5
  • PM10
  • nitrogen dioxide (NO2).


Europe (CAQI)

The Common Air Quality Index (CAQI) is an air quality index displayed on AirQualityNow EU.

Three major air pollutants are measured:

  • PM10
  • ground-level ozone (O3)
  • nitrogen dioxide (NO2)

If data on PM2.5, CO and SO2 is available, it is also included in the calculations.

The CAQI is evaluated on a scale from 0 to 100, where the lower the value is, the better air quality is while high values indicate bad air quality. The measurements are divided into five categories:

More detailed information can be found here.

In November 2017, the European Environment Agency announced the European Air Quality Index (EAQI). You can see its data on the Agency’s website.

United Kingdom (DAQI)

In the UK most air pollution information services use the Daily Air Quality Index (DAQI) and a four-band system approved by the Committee on Medical Effects of Air Pollutants (COMEAP) The system uses a scale from 1 to 10 and measures:

  • nitrogen dioxide (NO2)
  • sulphur dioxide (SO2)
  • O3
  • PM2.5
  • PM10

Air pollution is divided into four bands: Low, Medium, High and Very High.

Australia (AQI)

Each of the states and territories of Australia is responsible for monitoring air quality and publishing data in accordance with the national NEPM standards.

The following pollutants are monitored:

  • carbon monoxide (CO)
  • nitrogen dioxide (NO2)
  • ozone (O3)
  • sulfur dioxide (SO2)
  • PM10
  • PM2.5

South Korea (CAI)

The CAI (Comprehensive Air-quality Index) is a scale measuring ambient air quality in South Korea.

The CAI is based on measurements of the following air pollutants:

  • carbon monoxide (CO)
  • nitrogen dioxide (NO2)
  • ozone (O3)
  • sulfur dioxide (SO2)
  • PM10
  • PM2.5

The CAI uses a scale of 0 to 500. The higher the CAI value, the more severe the air pollution.

Singapore (PSI)

The PSI (Pollutant Standards Index) is based on six pollutants:

  • particulate matter (PM10)
  • fine particulate matter (PM2.5)
  • sulphur dioxide (SO2)
  • carbon monoxide (CO)
  • ozone (O3)
  • nitrogen dioxide (NO2)

For each pollutant, a sub-index is calculated, and the highest sub-index is taken as the PSI value. In most cases, it’s a PM2.5 concentration.

Hong Kong (AQHI)

From 1995 to 2013, Hong Kong used the Air Pollution Index (API), which was replaced by the AQHI system in 2013.

The Air Quality Health Index (AQHI) is a health risk-based air pollution index based on tracking the following air pollutants:

  • particulate matter (PM10)
  • fine particulate matter (PM2.5)
  • sulphur dioxide (SO2)
  • ozone (O3)
  • nitrogen dioxide (NO2)

The AQHI is reported on a scale from 1 to 10 and 10+, and is divided into five categories: low, moderate, high, very high, and serious.

Mainland China (AQI)

China’s AQI level is based on the level of six pollutants:

  • sulfur dioxide (SO2)
  • nitrogen dioxide (NO2)
  • PM10
  • PM2.5
  • carbon monoxide (CO)
  • ozone (O3)

India (AQI)

Air Quality Index (AQI) is a tool to showcase air quality status. It converts the complex air quality data of various pollutants into a single number and colour. AQI has six categories of air quality. These are: Good, Satisfactory, Moderately Polluted, Poor, Very Poor and Severe. Each of these categories is decided based on ambient concentration values of air pollutants and their likely health impact. As the AQI increases, an increasingly large percentage of the population is likely to experience health effects.