Updated On: 17 December, 2021 10:13 AM IST | Mumbai | mid-day online correspondent
The report also stated that PM2.5 concentration in Mumbai air is currently 13.5 times above the WHO annual air quality guideline value

Mumbai’s dipping air quality levels are a cause for concern. Pic/Getty Images
Air Quality Index (AQI) is a yardstick to measure the quality of air in a given area. It is measured from 0 to 500. A higher value of AQI denotes a greater level of pollutants in the air and hence a more severe impact on health.
The AQI index is divided into six categories, each corresponding to a different level of health concern.