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The air quality of Dhaka was measured ‘very unhealthy’ on Sunday morning, Air Visual–an international air quality monitoring organisation reports.

The Air Quality Index (AQI) was 195 at 10am on Sunday. In that particular time, Dhaka was ranked eighth among the world’s major cities having poor quality air.

According to Air Visual, the AQI was 251, 220 and 218 during 3am, 6am and 8am respectively on the day.

AQI 50 maximum is considered as healthy air. An AQI ranges between 151 and 200 is ‘unhealthy’ while 201 and 300 is ‘very unhealthy’. AQI above 300 is ‘dangerous’.

Air quality researchers say that air quality deteriorates if the temperature drops. Particularly during the late night and early morning, the amount of air polluting particulates may increase. The sources of pollutants remain the same for Dhaka. But, the extent of air pollution varies upon differences of the atmospheric pressure, flow and temperature. Air pollution increases during a high atmospheric pressure limits air flow and the temperature falls.

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Professor Ahmad Kamruzzaman Majumder, director at Center for Atmospheric Pollution Studies under the Stamford University Bangladesh, says, "Air pollution in Dhaka seems unavoidable to us. The main reason is that the sources of air pollutants are never controlled in a sustainable way. Rather, climatic causes are always blamed for air pollution. Air pollution could be minimised if the sources are controlled."

Researchers say that Dhaka’s air quality was falling since Saturday with several readings of AQI above 300. Intensity of particulate matters was very high in the air. On Saturday, concentration of the particulate matters spread around 10-12km radius in the sky. The situation remained unchanged during the night, resulting in bad AQI. Despite the low velocity of traffic movement and construction works on Sunday–which was a public holiday in Bangladesh, the AQI remained unhealthy.

Increasing temperature in the coming week

The morning of the 21 February was at bit cloudy. As the day rolled on, the day turned brighter, bBut the air remained cool. According to the meteorology department, there is no chance of rain in any place of the country on Sunday. But the days in the coming week would be a bit warmer. Meanwhile, the minimum temperature (at night) would decrease by 1-2 degree Celsius. Weather forecast by the meteorology department says that a trough of low lies over the sub-Himalayan West Bengal and adjoining area while the seasonal low lies over the South Bay.

The weather may remain dry with temporary partly cloudy sky over the country. Light fog may occur at places over the river basins of the country during early morning. Night temperature may fall slightly and day temperature may rise by 1-2 degree Celsius over the country.

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