Dhaka’s air quality showed improvement as it ranked 15th worst in the Air Quality Index (AQI) on Monday morning.   Dhaka had an AQI score of 87 at 08:38am and the air was classified as ‘Moderate’.   When the AQI value is between 51 and 100, active children and adult and people with respiratory diseases are advised to limit prolonged outdoor excretion.   China’s Shanghai, Vietnam’s Ho Chi Minh city and Poland’s Krakow occupied the first three spots in the list of cities with the worst air with scores of 164, 159 and 153 respectively.   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.