Dhaka’s air quality showed significant improvement on Friday morning as it ranked 69th worst in the Air Quality Index (AQI).   It had an AQI score of 27 at 08:48 am and its air quality was classified as ‘good’.   India’s Delhi, Pakistan’s Lahore, and China’s Beijing occupied the first three spots in the list of cities with the worst air with scores of 198, 188 and 155 respectively.   When the AQI value is between 0 and 50, the air quality is good.   Dhaka usually ranks among top 10 cities with worst air quality.   The AQI, an index for reporting 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.   In Bangladesh, the AQI is based on five criteria pollutants - Particulate Matter (PM10 and PM2.5), NO2, CO, SO2 and Ozone.   Dhaka has long been grappling with air pollution. Its air quality usually improves during monsoon.