<div style="text-align: justify; "><span style="font-size: 1rem;">After a marked improvement, Dhaka's air quality slipped back to the 'unhealthy for sensitive groups' category on Monday.</span><br></div><div style="text-align: justify;"><br></div><div style="text-align: justify;">With an air quality index (AQI) score of 102 at 9 am, the metropolis ranked 16th in the list of world cities with the worst air quality.</div><div style="text-align: justify; "><span style="font-size: 1rem;"><br></span></div><div style="text-align: justify; "><span style="font-size: 1rem;">Pakistan’s Lahore, China’s Chengdu and the UAE’s Dubai occupied the first three spots, with AQI scores of 176, 161 and 161, respectively.</span></div><div style="text-align: justify; "><span style="font-size: 1rem;"><br></span></div><div style="text-align: justify; "><span style="font-size: 1rem;">An AQI between 101 and 200 is considered 'unhealthy', particularly for sensitive groups.</span><span style="font-size: 1rem;"><br></span></div><div style="text-align: justify; "><span style="font-size: 1rem;"><br></span></div><div style="text-align: justify; "><span style="font-size: 1rem;">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.</span><br></div><div style="text-align: justify; "><span style="font-size: 1rem;"><br></span></div><div style="text-align: justify; "><span style="font-size: 1rem;">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.</span><br></div><div style="text-align: justify;"><br></div><div style="text-align: justify;">In Bangladesh, the AQI is based on five criteria pollutants -- Particulate Matter (PM10 and PM2.5), NO2, CO, SO2 and Ozone.</div><div style="text-align: justify;"><br></div><div style="text-align: justify;">Dhaka has long been grappling with air pollution issues. Its air quality usually turns unhealthy in winter and improves during the monsoon.</div><div style="text-align: justify;"><br></div><div style="text-align: justify;">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".</div><div style="text-align: justify;"><br></div><div style="text-align: justify;">With the advent of winter, the city’s air quality starts deteriorating sharply due to the massive discharge of pollutant particles from construction work, rundown roads, brick kilns and other sources.</div><div style="text-align: justify;"><br></div><div style="text-align: justify;">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 a heart disease, chronic respiratory diseases, lung infections and cancer, according to several studies.</div><div style="text-align: justify;"><br></div><div style="text-align: justify;">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. UNB</div><div style="text-align: justify;"><br></div><div style="text-align: justify; "> bnbd24/kh</div>