New Delhi today topped the list for being the most polluted city in the world, according to a real-time air quality ranking report by IQ Air Visual, a portal that tracks air quality and air pollution across the globe.
The ranking is calculated based on live tracking of the Air Quality Index or AQI of cities across the world. The list, released on their website, shows 50 most polluted countries with Delhi appearing right on top of the list at an AQI of 422 around 9 pm on Wednesday followed by Lahore in Pakistan and Hanoi in Vietnam.
According to the report, Delhi's air falls under the "hazardous" category - AQI 301 plus - and describes the air as a "serious risk of respiratory effects. Everyone should avoid outdoor activities". The website also has a map to track the air quality across the city at any given time, a daily air quality forecast and an hourly forecast.
The website also provides recommendations for the hazardous category - "Everyone should avoid outdoor exercise and take care to wear a pollution mask outdoors. Ventilation is discouraged. Air purifiers should be turned on."
Air Quality in Delhi fluctuated between "severe" and "hazardous" following Diwali weekend leaving the city covered in a thick blanket of smog. Through the week, the state government called for several measures to curb air pollution and issued advisories for safety from the smog.
Other Indian cities that find its place on the list include Kolkata at number ten with AQI at 158 and Mumbai city at number 28 with AQI 99.
An AQI between 0-50 is considered "good", 51-100 "satisfactory", 101-200 "moderate", 201-300 "poor", 301-400 "very poor", and 401-500 "severe". Above 500 is "severe-plus emergency" category.
The AQI takes into account five chief pollutants - particulate matter with a diameter less than 10 micrometres (PM10), PM2.5, ozone (O3), nitrogen dioxide (NO2), and carbon monoxide (CO).
According to a 2018 report by the same website, Gurgaon in the National Capital Region or NCR was ranked the world's most polluted city and of the 10 cities with highest pollution, seven were in India. Delhi was at number 11 on the pollution chart.