Dhaka experienced the highest level of air pollution among cities across the world on Tuesday as its air quality index (AQI) has soared to 608 ppm (presence of pollutant particles).
A smart phone app -- Air Visual -- revealed the information of AQI received from the air quality monitoring station at the US embassy in Dhaka.
Other cities in the world that follow Dhaka in severity of air pollution are Shanghai of China, Ulaanbaatar of Mongolia, Hangzhou and Chengdu of China, Lahore of Pakistan and Kolkata and Delhi of India.
Not only the capital city of Dhaka, excessive harmful particles has been found in the air of Gazipur, Narayanganj, Khulna, Rajshahi, Sylhet and Barisal during the winter, especially in January.
On Monday, the highest level of air pollution was recorded at 565ppm in Narayanganj followed by 556 ppm in Dhaka, 402 ppm in Khulna, 386 ppm in Gazipur, 308 ppm in Rajshahi, 274 ppm in Barisal, 264 ppm in Sylhet and 174 ppm in Chittagong, according to a report of Clean Air and Sustainable Environment (CASE) Project under the Department of Environment.
The index is based on five criteria pollutants regulated under the Clean Air Act — ground-level ozone, particulate matter, carbon monoxide, sulfur dioxide, and nitrogen dioxide.
The Department of Environment (DoE) has also set national ambient air quality standards for these pollutants. The standards have been set with an aim to protect human health from adverse impacts of air pollution.
The AQI standard for Bangladesh is 0-50 (good), 51-100 (moderate), 101-150 (caution), 151-200 (unhealthy), 201-300 (very unhealthy) and 301-500 (extremely unhealthy).
The CASE project has found extremely unhealthy air in Dhaka, Gazipur, Narayanganj, Khulna and Rajshahi on Monday while the pollution level has exceeded the AQI standard in Dhaka and Narayanganj.
In Dhaka, air quality measure cams have been set up in Sangshad Bhaban, Farmgate and Darus-Salam areas of the capital.
According to CASE data, the air was extremely unhealthy in Dhaka (416ppm), Narayanganj (821ppm), Gazipur (440ppm), Chittagong (312ppm), Barisal (349ppm) and Sylhet (237ppm) on January 18, 2017.
Air becomes extremely unhealthy in the cities in winter as the presence of pollutant particles in their air even on a normal day is 4-8 times higher than the safe limit.
Air pollution is a major threat to human health worldwide and toxic air pollutants are linked to high risk of stroke, heart ailment, cancer and respiratory diseases, including asthma, experts said.
DoE Director (air quality management) Ziaul Haque told the daily sun that the presence of pollutant particles in the air of Dhaka and other major cities has usually increases in winter.
Many brick kilns surrounding the capital city start operation during winter.
Development work like repair and road digging and construction also run in this season which also causes air pollution, he said.
Earlier, the DoE reported that brick kilns are responsible for 58 percent air pollution while road dust and soil dust 18 percent, vehicles 10 percent, burning biomass 8 percent and other sources 6 percent, he said
Ziaul Haque said they are trying to check air pollution.“We have already directed the authorities to do their development work by taking several precautionary measures.
Dr Akhtar Hossain, professor and respiratory specialist of Dhaka Medical College, said respiratory problem, sinusitis, allergy, dust allergy, rhinitis, throat infection, asthma, pneumonia, bronchiolitis, nose blockage, persistent cough and renal damage are caused by breathing dust and unhealthy air.
Different respiratory and lung diseases mainly occur due to air pollution, he said adding that long time air pollution may cause deadly lung cancer.