The Air Quality Index Explained

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air quality index

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The Air Quality Index (AQI) is a tool used to measure air quality and the potential effects of air pollution on human health. The AQI is based on a scale of 0 to 500, where the higher the value, the greater the level of air pollution and associated health risks. In this post, we’ll dive into what the AQI is, how it works, and what each score means for your health and well-being.

What is the Air Quality Index (AQI)?

air quality index explained

The Air Quality Index (AQI) measures how clean or polluted the air is in a specific location. Government agencies and environmental organizations use the AQI to communicate the health risks of air pollution to the public. 

The AQI is calculated based on measurements of several air pollutants, including ground-level ozone, particulate matter, carbon monoxide, sulfur dioxide, and nitrogen dioxide. The AQI scale typically ranges from 0 to 500, with higher scores indicating higher levels of air pollution.

A Brief History of the AQI

The AQI was first introduced by the United States Environmental Protection Agency (EPA) in the 1970s to provide a standardized way to communicate air quality to the public. The original AQI scale ranged from 0 to 500 and included five categories: Good, Moderate, Unhealthy for Sensitive Groups, Unhealthy, and Hazardous. 

In 1999, the EPA revised the AQI scale to better reflect the health risks associated with air pollution. The new AQI scale ranges from 0 to 500 and includes six categories: Good, Moderate, Unhealthy for Sensitive Groups, Unhealthy, Very Unhealthy, and Hazardous.

How the AQI is Calculated

The air quality index is calculated based on measurements of several air pollutants, including ground-level ozone, particulate matter, carbon monoxide, sulfur dioxide, and nitrogen dioxide. 

The AQI is calculated for each pollutant individually, and the highest value is reported as the AQI for a specific location. For example, if the AQI for ground-level ozone is 80 and the AQI for particulate matter is 70, the AQI for the location would be reported as 80 since that is the higher of the two values.

The AQI scale is divided into six categories, each corresponding to a range of AQI values and a description of the health risks associated with that level of air pollution. The categories are as follows:

  • Good (AQI 0-50): Air quality is considered satisfactory, and air pollution poses little or no risk.
  • Moderate (AQI 51-100): Air quality is acceptable, but some pollutants may cause health problems for a few people sensitive to air pollution.
  • Unhealthy for Sensitive Groups (AQI 101-150): Members of sensitive groups, including children, older adults, and people with heart or lung disease, may experience health effects.
  • Unhealthy (AQI 151-200): Everyone may begin to experience health effects, and members of sensitive groups may experience more severe health effects.
  • Very Unhealthy (AQI 201-300): Everyone may experience more serious health effects, and people with heart or lung disease, older adults, and children are at greater risk.
  • Hazardous (AQI 301-500): Health warnings of emergency conditions. The entire population is more likely to be affected.

It is important to note that the AQI is a relative measure of air quality and not an absolute measure. A score of 50 in one area may be good air quality, while a score of 50 in another may be unhealthy. [irp posts=”9916″ ]

Additionally, some pollutants, such as carbon monoxide, can reach dangerous levels even if the AQI is relatively low. Therefore, it is essential to monitor air quality levels and take precautions accordingly, regardless of the AQI score.

Uses of the AQI

air quality monitoring
  • Public Health: The AQI is used by public health officials to alert the public about the quality of the air in their area. The AQI provides information about the potential health effects of air pollution, such as respiratory problems, heart disease, and cancer. The information helps people make informed decisions about outdoor activities, and vulnerable groups such as children and older people can take precautions to avoid exposure to poor air quality.
  • Environmental Regulations: The AQI is used by government agencies to regulate air pollution. The AQI serves as a tool to determine whether an area complies with air quality standards set by the Environmental Protection Agency (EPA) and other regulatory agencies. The AQI helps agencies monitor and enforce air quality regulations, and it provides a way to track improvements in air quality over time.
  • Industrial and Business Planning: The AQI is used by industrial and business planners to assess the impact of their activities on air quality. The AQI helps businesses and industries identify areas where air pollution is high due to their activities. By understanding the impact of their activities on air quality, businesses, and industries can take steps to reduce emissions and improve air quality in their communities.
  • Educational Purposes: The AQI is used in schools and universities to teach students about the importance of air quality and the potential health effects of air pollution. The AQI provides a way to track air quality trends over time and raise awareness about the impact of air pollution on public health and the environment. Educators can help students understand the link between air quality and human health using the AQI in the classroom.

Conclusion

In conclusion, the Air Quality Index (AQI) is a powerful tool for measuring and reporting air quality levels in an easily understandable way to the general public. It helps people make informed decisions about their daily activities and take steps to protect themselves from the harmful effects of air pollution. 

By tracking trends in air pollution over time and evaluating the effectiveness of air pollution control programs, the AQI is a critical tool in the fight for clean air. Whether you are an individual concerned about your health or a policy maker working to improve air quality for your community, the AQI is an essential resource in your toolkit.

  • Luke Rooks

    Luke is a passionate environmental advocate based in upstate New York. When he's not sharing tips on sustainability and wellness, you can find him hiking with his dog, Max.

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