Air Quality Index (AQI)

The air quality index is an indicator of air quality and its effects on health.

The air quality index (AQI) is an indicator that assesses the current air quality based on the concentration of various air pollutants, particularly considering the short-term health effects of these pollutants on humans. The AQI serves as an aggregated health indicator summarizing the exposure to the main air pollutants such as nitrogen dioxide (NO₂), ozone (O₃), fine particulate matter (PM10 and PM2.5), carbon monoxide (CO), and to some extent, sulfur dioxide (SO₂). The goal of the AQI is to quickly and clearly inform vulnerable groups such as children, the elderly, and individuals with pre-existing conditions about potential health risks.

Measurements are made at a network of stationary monitoring stations installed in urban and rural areas. A single index is calculated for each pollutant, with the overall AQI corresponding to the highest individual index value. The values are categorized into assessment categories ranging from "very good" to "very poor." The AQI focuses on short-term health effects, such as irritations of the respiratory tract and acute cardiovascular issues.

The AQI is a central tool for authorities and the public to monitor air quality, communicate risks, and take targeted measures for air purification. In many cities, the AQI is integrated into smart city systems to respond in real time to changes in air quality. Despite its significance, the AQI has limitations as it only provides a momentary assessment of air quality and does not account for long-term risks.