80% of the world’s population lives under skies affected by light pollution. Light pollution is higher in the Chattogram port area compared to other regions, due to the use of floodlights in the port.
The famous lines from Bengali poet Jatindramohan Bagchi’s famous poem ‘Kajla Didi’ – Pukur dhare lebur tole, thokai thokai jonak jole, fuler gondhe ghum ashe na, ekla jege roi (Under the lemon tree on the bank of pond, fireflies light up in groups; I can’t fall asleep, thus, remaining awake alone) — or the timeless lyrics from Indian musician Hemanta Mukhopadhyay’s evergreen song: Ei raat tomar amar, oi chand tomar amar, sudhu dujonar (this night is mine and yours, that moon is mine and yours, they just belong to both of us) – continue resonating in our minds regardless of our social strata and age.
Other than these classics, many of us now find ourselves humming contemporary songs that celebrate and enjoy the beauty of darkness and the night. Yet, it is unfortunate that we are nearly oblivious to the fact that the darkness of night is slowly disappearing from our lives.
The world is constantly evolving, transforming into an even stronger global economy by the day. This leads to an increase in the number of factories, various establishments, and a growing expansion of urbanisation and human needs, all of which require day and night activities both at indoors and outdoors.

Keeping pace with these growing changes, scientists are continuously conducting research to identify the causes of various environmental pollutants and to find solutions to issues, including water pollution, soil pollution, air pollution, and noise pollution, resulting from globalisation. Amid the concern for all these forms of pollution, one has slipped our minds: light pollution.
Light pollution, also known as photo pollution, is defined as the invasion of artificial light caused by excessive and inappropriate use. It is an environmental hazard. Simply put, the unnecessary or excessive use of artificial light is referred to as light pollution.
Light pollution is increasing, with artificially lit outdoor areas rising by 2.2 per cent per year from 2012 to 2016, according to the study cited by the Secretariat of the Convention on Migratory Species of Wild Animals (CMS), a UN environmental treaty.

‘Light pollution storm’ brewing silently
In the first go, you may find it strange as to what light pollution even occurs and how. Such questions involving this widespread form of pollution will surely come as a surprise to hundreds of millions of people across the world.
But this is what we have already been silently suffering from for years now.
Light, which has transformed the world and wakes us up in the morning, is now causing pollution, threatening both human and wildlife. Yes, it is causing pollution.
Artificial light from our homes, streets, parks, shopping malls, factories, and vehicles is all contributing to light pollution. The dazzling display of this artificial light continues from sunset until sunrise. Night is no longer truly dark but instead illuminated by artificial lights, whether in villages or cities. It has become difficult to find a natural night sky, and the situation is even worse in developed countries.
This pollution is robbing us of the natural darkness of night, almost like a silent killer. The light from millions of stars has been overshadowed by artificial lights, disrupting the life cycles of nocturnal animals.
The majority of the world’s population now lives under light-polluted skies, making excessive artificial light a global concern.

Grim scenario
A study launched in June 2016 in the Science Advances journal said that a staggering 80% of the world’s population lives under skies affected by light pollution.
The situation is even worse in the USA and Europe, where 99% of people are deprived of experiencing a natural night due to light pollution, adds the study titled ‘The new world atlas of artificial night sky brightness’.
Astronomers first brought attention to the concept of light pollution in the mid-1970s, highlighting the issue of bright night skies due to artificial lighting. Research on light pollution and its impact on the environment began in 1980, and its effects on ecosystems have already been detected.
According to various studies, the level of light pollution has multiplied over the past 50 years. Scientists have reported that the spread of artificial light expanded by 2% per year between 2012 and 2016, with the potential for even greater increases in the future.
The impact of light pollution is most noticeable in the developed world, particularly in Europe, America, Singapore, Canada, and Dubai, where 99% of the population lives under skies illuminated by artificial light. In contrast, different conditions are observed in places like Siberia, deserts, and the Amazon rainforest, where the absence of artificial light at night allows for clear views of starlight and the Milky Way.
The Science Direct magazine in a 2021 publication revealed that artificial light at night is globally increasing, posing a threat to biodiversity.
The artificial light also impacts species interactions, including intra-specific communication, trophic interactions and plant–pollinator interactions, with cascading effects in the ecosystem and impacts on ecosystem functioning that extend beyond nocturnal communities and illuminated areas, the publication added.
A study published in the BioScience revealed that the use of artificial light has increased significantly in comparison to urbanization over the last century. This artificial light is severely affecting the breeding process of fireflies.
Fireflies bearing the brunt
The impact of light pollution is far-reaching. In some cases, the intensity of artificial light is sharper than that of a full moon, making it difficult for fireflies to breed, as the light signals they use during their mating process are lost amid the brightness of artificial light.
Fireflies generate light with the help of a chemical called luciferin. Light is produced when luciferin mixes with oxygen, ATP, and magnesium ions in the presence of luciferase, an enzyme found in fireflies. This chemical process is known as bioluminescence. The brightness and duration of the light depend on the amount of oxygen in the firefly’s body.
According to scientists, these light signals are essentially the firefly’s language of love. Male fireflies flash light signals to attract females, who respond with rhythmic light patterns of their own. However, the bright lights from houses, streetlights, and electric billboards are disrupting the communication between male and female fireflies. This finding was highlighted by the lead researcher in a study published in BioScience, the monthly peer-reviewed scientific journal that is published by Oxford University Press.

Experts wary of wildlife debacles
Sara Lewis, a biology professor at Tufts University in the USA, said in an interview with CNN that many wildlife species have lost their habitats to urbanization, which exposes them to existential threats.
A British news site also stated that the usual life cycle of fireflies is being disrupted for another reason. It reported that the sighting of fireflies at night has become popular among tourists in countries like Japan, Taiwan, and Malaysia, with around 200,000 tourists participating in this form of tourism every year, which is significantly disrupting the natural lives of fireflies.
According to a report published on Science.org in 2016, light pollution can affect our vision more than the light of the Milky Way. In addition, strong artificial light can cause migratory birds to move at the wrong times, create obstacles for pollination by bats, and disrupt aquatic ecosystems.
Nocturnal insects naturally navigate using starlight, but artificial lights have become a death trap for these insects. Birds also struggle with navigation due to light pollution, often resulting in collisions with illuminated buildings.
Aside from wildlife, light pollution also affects human life. It can significantly reduce the production of melatonin, a hormone that helps people sleep, and can sometimes increase the risk of certain cancers. It is said that the harmful effects persist even if artificial light is reduced or turned off for a period.

The situation in Bangladesh
An analysis of satellite images on light pollution reveals that this type of pollution is increasing day by day in Bangladesh and its neighboring countries, including India.
After analyzing the VIIRS images from, it was found that the severity of light pollution is higher in the Chattogram port area compared to other regions, due to the use of floodlights in the port. Additionally, the severity of light pollution in Dhaka is now much higher than ever before. In contrast, light pollution is almost nonexistent in Rangamati and Khagrachhari.
The satellite image analysis indicates that the severity of light pollution is higher in industrial areas, as bright lighting is required in those zones.
Per Indian media reports based on various surveys, the number of illuminated areas increased by 33% between 2012 and 2016. Artificial lighting has grown in proportion to the expansion of power coverage. Although improved power access has enhanced the quality of people’s lives, it has harmed the environment, according to environmental experts.

How does light pollution harm humans?
The brightness of the night sky in populated areas is nearly 100 times higher than in desolate areas.
However, an analysis of satellite images revealed that the severity of light pollution varies by time and country. Various research findings indicate that excessive exposure to artificial light has affected both humans and animals in numerous ways, including causing sleep disorders. Human and animal bodies function according to their biological clocks, which help them distinguish between day and night. Light pollution, however, is disrupting the functioning of these clocks, leading to sleep disturbances. This insomnia affects their eating habits and reproductive processes, raising concerns among scientists about the potential extinction of various species in the near future.
Experts explain that a hormone called melatonin increases in the human body when the sun sets, promoting sleep. Another hormone, beta-endorphin, is produced during sleep and acts as a natural painkiller. Additionally, sound sleep helps regulate insulin levels in the body. Conversely, light pollution is linked to mental stress, insomnia, diabetes, and cardiovascular diseases. According to the New York Academy of Sciences, light pollution may also indirectly contribute to cancer.
Scientists believe that a healthy person can see around 4,000 stars with the naked eye in the night sky, but this number has dropped to about 1,000 due to light pollution.
The International Dark Sky Association established with the aim of controlling light pollution in 1988 has been conducting various awareness campaigns. The skies over several national parks and sanctuaries are monitored by the Natural Sound and Night Skies Division of America’s National Park Service.
The association estimates that 35% of artificial light is wasted just by being poorly aimed or unshielded.
Specific and controlled use of light can help mitigate the problem to some extent. Another way to reduce light pollution is by completely banning artificial light in certain areas at night, similar to the approach taken in Eifel National Park, which was declared a Star Sanctuary in 2014. Germany now has four such designated areas.
Reduced or more efficient use of light can save power and provide relief to both humans and animals. A serious threat awaits us if governments do not implement policies to curb light pollution.
Time to act
Even though a number of countries have incorporated provisions regarding light pollution in their laws, Bangladesh has yet to do so.
Experts suggest that the government include mandatory clauses in the important environmental laws including the Environment Conservation Act 1995, the Wildlife (Conservation and Security) Act 2012, and the Bangladesh Biodiversity Act 2017 to fight the ‘silent killer’.
Urban expert Prof Dr Nazrul Islam, however, thinks the light pollution is not still so serious in Dhaka, but it is time to think about it.
“Though lighting isn’t so extreme here, the excessive lighting should be controlled during celebrations,” he told the UNB news agency previously.
Prof Islam said urban planners now need to consider the light pollution in their future works.