Bright stars missing from Dhaka sky

Experts put the blame on light pollution as well as air pollution

Hanzala Han and Arfin Soriyat

Bonik Barta photo

Stars are most visible in haor areas, as light pollution does not exist there. And, air pollution is also low. On the contrary, Dhaka sky lacks brightness of the stars. According to related data, a layer has been formed in Dhaka’s sky due to different kind of pollutions. The residents of the capital can see up to the layer. The sky beyond the layer is not visible to them. As a result, the brightness of the stars in the nightly sky remains elusive to the Dhaka dwellers. Experts say light pollution is mainly to blame for that. Air pollution is also somewhat responsible. Dhaka is now one of worst cities in the world when it comes to air pollution.       

According to information available from IQAir, a mechanism to measure the air quality, among 100 cities in the world, Dhaka was the sixth worst city on Saturday with a score of 159. In March, the score was 212. Earlier in January, 2022, average air quality score of the Bangladeshi capital was 269.

Score between 50 and 100 are considered moderate or acceptable, as per the standard set by IQAir. If the score is between 101 and 150, it is regarded as unhealthy for the sensitive group of people. Score between 151 and 200 is unhealthy. Score between 201 and 300 is very unhealthy while score above 301 is considered disastrous or dangerous.

According to light pollution map, a website that measures brightness of artificial lighting, the rate of brightness in Dhaka sky on Saturday was 2,120 macrocandela per square meter. At the same time, it was only 93.9 in Sunamganj.

Information available from NASA satellite also indicates that Dhaka is the most luminous city in the country. Artificial brightness is the highest in Gulshan area with 2,250 macro candela. The natural brightness here is 2.42 millicandela (MCD). In the Hazrat Shahjalal International Airport area, natural brightness is 2.15 MCD while the artificial lighting is 1,760 macrocandela. Among other areas, artificial brightness in Ramna is 1,810 macrocandela, 1,960 macrocandela in Gulistan and 462 macrocandela in Mirpur.           

“Air pollution and light pollution are responsible for missing stars in the sky of Dhaka,” Professor Dr Ishtiaque M Syed, director of Dhaka University’s Centre for Advanced Research, told Bonik Barta.

A research paper recently published in the ‘Journal of Bangladesh Institute of Planners’ also affirmed the increase of light pollution in the country. As per the research showed that light pollution is the worst in Dhaka. The research titled ‘Nexus between Light Pollution and Air Temperature: A Study of Bangladesh’ was conducted with the information from 2003 till 2013. Khulna University Professor Dr Kazi Saiful Islam and urban planner Aninda Sundar Howlader carried out the research.    

After Dhaka, Chittagong is the second worst in terms of light pollution followed by Khulna, Sylhet, Rajshahi, Jessore and Rangpur. In 2003, light pollution used to take place in only 7.1 percent area of the country. It went up to 25.4 percent in a one decade. In 2003, light pollution was only a matter for cities and towns. But, it spread to suburbs in 2013.

According to United States Center for Biological Diversity, Saint Petersburg of Russia is the worst affected place in the world when it comes to light pollution. The brightness of artificial in this city is more than eight times higher than world’s average luminousness. Makkah of Saudi Arabia comes second while Russia’s Chelyabinsk and Kuwait City rank third and fourth respectively.

“The sky of Dhaka is heavily polluted. Different chemicals, including dust and glass, from earth merge with sky resulting in the creation of a layer in sky over Dhaka. On the top of that there is light pollution”, Sujaul Islam Khan, Assistant Professor of Department of Architecture at North South University and Environment and Urbanization Secretary of Institute of Architects Bangladesh (IAB),  told Bonik Barta.

“As the stars are many light years away, their presence can be felt in a subtle way. But, we cannot see those stars because of too much lighting surrounding us,” he added.

Environmentalist Franz Hölker of Germany’s Leibniz-Institute of Freshwater Ecology and Inland Fisheries said, “Natural light circulation is interrupted by the artificial lighting, increasing pollution of light which seriously affects environment. Besides, too much brightness hinders people’s sound health.              

American Medical Association says that very powerful but weakly designed LED bulbs are very risky with respect to necessary hormone melatonin.

Professor Dr Md Moniruzzaman, former head of Geography and Environment Department at the Jagannath University, said, “Light pollution is negatively affecting every single ecosystem, especially nocturnal animals and insects. They are scared of getting out of their dens resulting in less births. After getting confused by brightness, many diurnal birds and insects are seen flying at nights.”

“Reproduction of nocturnal insects is hindered due to artificial lighting. Pollination of trees, which depend on insects, is also impeded. As a result, production is gradually going down. The artificial light at night is also posing threat to aquatic animals,” he said.   

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