Bangladesh’s capital Dhaka ranked sixth worst in the Air Quality Index (AQI) on Monday morning.   It had an AQI score  of 140 at 08:06am.   The air was classified as ‘unhealthy for sensitive groups’.   When the AQI value is between 101 and 150, active children and adults, and people with respiratory diseases, such as asthma, should limit prolonged outdoor exertion.   India’s Delhi, Thailand’s Chiang Mai and Pakistan’s Lahore occupied the top three spots in the list of cities with the worst air quality with AQI scores of 175, 160 and 158 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 (O3).   Dhaka has long been grappling with air pollution. Its air quality usually improves during monsoon.