Dhaka, Oct 18 : The Air Quality Index (AQI) of Dhaka, one of the most polluted cities in the world, was on Sunday ranked as the worst in the world. In Bangladesh, the AQI is based on five pollutants: Particulate Matter (PM10 and PM2.5), NO2, CO, SO2 and Ozone, The Daily Star newspaper reported. At 10,24 a.m. on Sunday, Dhaka had an AQI reading of 188 and the air was classified as "unhealthy". Pakistan's Lahore and India's New Delhi occupied the second and third spots on the list with scores of 178 and 176 respectively. The AQI, an index for reporting the daily air quality, informs people how clean or polluted the air of a certain city is and what associated health effects might be a concern for them. According to an IQAir AirVisual report, Bangladesh topped the list of the world's most polluted countries in 2019 for PM2.5 exposure. /IANS