Air Quality Index (AQI)
The Air Quality Index (AQI) is a vital tool used to communicate the health risks associated with ambient air quality in specific areas at particular times. Developed by the U.S. Environmental Protection Agency (EPA), the AQI provides a standardized method for assessing air pollution levels, which has been adopted and adapted by various countries worldwide. Regular measurements of key air pollutants, such as particulate matter, ozone, nitrogen dioxide, sulfur dioxide, and carbon monoxide, allow authorities to assign a numerical value to air quality, reflecting its potential health impact.
The AQI uses a color-coded system to categorize air quality levels, with higher numbers indicating greater health risks. While the specific pollutants monitored can vary by region, the core methodology remains consistent globally. Monitoring typically focuses on urban areas where pollution levels are more pronounced. However, some countries, like Hong Kong, have faced criticism for having looser standards, leading to discrepancies between reported safe levels and those deemed acceptable by international health organizations like the World Health Organization. The AQI serves as an essential resource for the public, helping individuals make informed decisions regarding outdoor activities based on air quality conditions.
Subject Terms
Air Quality Index (AQI)
DEFINITION: The US Environmental Protection Agency’s tool for indicating the health risks posed by ambient air quality in given areas at particular times
With air pollution a growing problem the world over, the Air Quality Index and equivalent tools in other nations have become an indispensable part of regional and federal governments’ efforts to convey information on ambient air quality to the general public.
Nations around the world employ a number of variations on the Air Quality Index (AQI) developed by the US Environmental Protection Agency (EPA), but the basic methodology used to assess air quality is the same. The concentrations of various air pollutants in a testing area are measured regularly, and, based on this information, the area is assigned a number. This number fits into a color-coded rating system in which different tiers correspond to the severity of the health threat the air quality poses; the higher the number, the more severe the threat.
Although a host of air pollutants have the potential to cause adverse health effects, only a handful of criteria contaminants are generally used in the assessment of basic air quality. Individual criteria differ from place to place, but the most common pollutants monitored are suspended particulate matter, airborne lead, ground-level ozone, nitrogen dioxide, sulfur dioxide, and carbon monoxide. These hazardous compounds are capable of causing severe respiratory irritation, heart and circulatory problems, and other negative health effects.
Monitoring sites are typically limited to cities and towns, where levels and densities are both high. Different levels of pollution may fall into different tiers based on the stringency of a particular agency’s approach to measuring air quality. For example, Hong Kong’s Air Pollution Index has come under heavy criticism for its relatively lax standards, as the air quality it rates as safe sometimes contains pollutants at levels several times higher than those considered acceptable by the World Health Organization.
"Air Pollution: The Invisible Health Threat." World Health Organization, 12 July 2023, www.who.int/news-room/feature-stories/detail/air-pollution--the-invisible-health-threat. Accessed 12 July 2024.
"Air Quality Index." American Lung Association, 2 Nov. 2023, www.lung.org/clean-air/outdoors/air-quality-index. Accessed 12 July 2024.
"Air Quality Index (AQI) Basics." AirNow, www.airnow.gov/aqi/aqi-basics/. Accessed 12 July 2024.
Hu, Shelia. "What Is the Air Quality Index?" Natural Resources Defense Council, 27 Sept. 2023, www.nrdc.org/stories/what-air-quality-index. Accessed 12 July 2024.