Air quality index

Air Quality Index (AQI) is a numerical scale used for reporting the quality of the air in a specific area. It is an important tool for measuring air pollution and its potential impact on human health. The AQI is calculated based on the concentrations of several major air pollutants, including particulate matter (PM10 and PM2.5), ozone (O3), nitrogen dioxide (NO2), sulfur dioxide (SO2), and carbon monoxide (CO). Different countries may have their own AQI systems, with variations in the pollutants measured, the scale used, and the health advisories associated with different AQI levels.

Overview

The AQI is designed to provide the public with an easy way to understand the air quality in their area and its potential health effects. An AQI value is typically divided into ranges, and each range is assigned a descriptor (such as Good, Moderate, Unhealthy, etc.) and a color code to help people understand whether air pollution levels pose a health risk. The general principle is that a lower AQI value represents cleaner air and a lower health risk, while a higher AQI value indicates poorer air quality and higher health risks.

Calculation

The AQI is calculated for each pollutant (PM2.5, PM10, O3, NO2, SO2, and CO) based on the concentration of that pollutant in the air. Each pollutant has a different scale for what constitutes good, moderate, unhealthy, or hazardous air quality. The overall AQI value for a specific location is the highest AQI value obtained among all the pollutants measured. This means that if any single pollutant's concentration is in the unhealthy range, the overall AQI for that location will be considered unhealthy.

Health Implications

The health implications of different AQI levels vary depending on the AQI category. For example: - 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; however, there may be a risk for some people, particularly those who are unusually sensitive to air pollution. - Unhealthy for Sensitive Groups (AQI 101-150): Members of sensitive groups may experience health effects, but the general public is unlikely to be affected. - Unhealthy (AQI 151-200): Everyone may begin to experience health effects; members of sensitive groups may experience more serious health effects. - Very Unhealthy (AQI 201-300): Health warnings of emergency conditions. The entire population is more likely to be affected. - Hazardous (AQI 301-500): Health alert: everyone may experience more serious health effects.

Preventive Measures

When AQI levels are high, it is advisable to take preventive measures to reduce exposure to air pollutants. Such measures may include staying indoors, using air purifiers, avoiding strenuous outdoor activities, and wearing masks designed to filter out particulate matter.

Global Variations

Different countries have their own AQI systems, reflecting local air quality standards, health advisories, and the pollutants included in the index. For example, the United States Environmental Protection Agency (EPA) uses a system that includes five major pollutants, while other countries might include additional pollutants or use different thresholds for health advisories.

See Also

• Environmental protection
• Pollution
• Respiratory health