An Air Quality Index (AQI) bulletin released by the Central Pollution Control Board (CPCB) has listed seven cities from Karnataka among the 13 cities with ‘good air quality’ in India. Released on Sunday, November 24, the bulletin ranks the air quality of 262 cities across the country, based on the data of the past 24 hours. Karnataka’s Chamarajanagar, Bagalkot, Haveri, Kolar, Madikeri, Mangalore, and Vijayapura have AQI levels between 0 and 50, indicating minimal air pollution and negligible health impacts.
Other cities with good air quality include Aizawl (Mizoram), Cuddalore, Thanjavur, Tirunelveli (Tamil Nadu), and Kannur, Thrissur (Kerala). While these cities enjoy clean air, many others like Delhi, Mumbai, and Nagpur report ‘poor’ air quality, while Dhanbad and Visakhapatnam fall under the ‘very poor’ category.
AQI is calculated based on the concentration of five major pollutants in the air: PM2.5 (particulate matter), PM10, carbon monoxide (CO), nitrogen dioxide (NO2), and ozone (O3). Each pollutant is assigned a value which corresponds to a specific AQI category, ranging from ‘good’ (0-50) to ‘severe’ (401-500). The highest AQI value among these pollutants determines the overall AQI of a particular location. PM refers to tiny particles or droplets suspended in the air. These particles can be solid or liquid and are classified by their size. PM2.5 refers to particles with a diameter of 2.5 micrometres or smaller, while PM10 refers to particles 10 micrometres or smaller.
When the AQI is between 0-50, it poses minimal health impact. For the 51-100 range, sensitive individuals might experience minor breathing discomfort and in the 101-200 range, people with lung, asthma, or heart conditions could experience breathing discomfort. An AQI of 201-300, termed ‘poor’ may cause breathing discomfort for most individuals, with prolonged exposure. The ‘very poor’ category (301-400) can lead to respiratory illness upon prolonged exposure, and an AQI of 401-500, which is considered ‘severe’ can affect healthy people and seriously impact those with existing health conditions.