On Wednesday (March 24, 2021), Dhaka occupied the third position in the list of world cities with the worst air quality. The capital's air quality index (AQI) was recorded at 198 around 11.35 am. India’s Delhi and Nepal’s Kathmandu occupied the first two positions in the list, with AQI scores of 266 and 213, respectively. Read Dhaka is world's most polluted city An AQI between 101 and 200 is considered 'unhealthy', particularly for sensitive groups. Similarly, an AQI between 201 and 300 is said to be 'poor', while a reading of 301 to 400 is considered 'hazardous', posing serious health risks to residents. AQI, an index for reporting daily air quality, is used by government agencies to inform people how clean or polluted the air of a certain city is, and what associated health effects might be a concern for them. Read Public health issues like air pollution, environment not getting due attention In Bangladesh, the overall AQI is based on five criteria pollutants – Particulate Matter (PM10 and PM2.5), NO2, CO, SO2, and Ozone (O3). The Department of Environment has also set national ambient air quality standards for these pollutants. The densely populated capital of Bangladesh has long been grappling with air pollution issues. The air quality usually improves during monsoon. Read Lung cancer on the rise in Bangladesh: Report A report by the Department of Environment (DoE) and the World Bank in March 2019 pointed out that the three main sources of air pollution in Dhaka "are brick kilns, fumes from vehicles and dust from construction sites". Air pollution consistently ranks among the top risk factors for death and disability worldwide. Breathing polluted air has long been recognised as increasing a person’s chances of developing heart disease, chronic respiratory diseases, lung infections and cancer, according to several studies. Also Read: No respite from pollution as Dhaka's air quality still 'unhealthy' As per the World Health Organization (WHO), air pollution kills an estimated seven million people worldwide every year, largely as a result of increased mortality from stroke, heart disease, chronic obstructive pulmonary disease, lung cancer and acute respiratory infections. Over 80 percent living in urban areas which monitor air pollution are exposed to air quality levels that exceed WHO guideline limits, with low- and middle-income countries most at risk. Also Read:  Dhaka keeps grappling with 'hazardous' air

The air quality of Dhaka showed signs of improvement on Monday morning.   The capital was ranked 7th worst in the Air Quality Index (AQI) with a score of 134, around 8am.   The air quality was classified as ‘moderate’.   Myanmar’s Yangon, China’s Shenyang, China’s Chengdu occupied the first three spots in the list of cities with worst air with scores of 175, 162, and 154 respectively.   When the AQI value is between 101 to 150 it means ‘Unhealthy for Sensitive Groups’.   Although general public is not likely to be affected at this AQI range, people with lung disease, older adults and children are at a greater risk from exposure to ozone, whereas persons with heart and lung disease, older adults and children are at greater risk from the presence of particles in the air.   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.

The air quality of Dhaka showed a sign of improvement on Wednesday morning.   The capital ranked 18th worst in the Air Quality Index (AQI) with a score of 118. The air quality was classified as ‘unhealthy’.   China’s Shenyang, Chengdu, Guangzhou occupied the first three spots in the list of cities with the worst air with scores of 189, 176 and 171 respectively.   When the AQI value is between 101 to 150 it means ‘Unhealthy for Sensitive Groups’.