2023-06-15 18:48:21
Man turns night more and more into day with artificial light. Both the extent of light pollution and its geographical extent are increasing rapidly – with growing negative effects on living beings such as humans and on ecosystems, researchers warn in the journal Science. The light, which is often wasted, requires enormous amounts of electricity, which not only causes high costs but also considerable greenhouse gas emissions, according to the scientists.
In five overview articles, researchers document the profound effects of light pollution on humans, animals and ecosystems as well as the consequences for astronomy, which sees less and less in the increasingly bright night sky. The authors include the epidemiologist Eva Schernhammer from the Medical University of Vienna and the astrophysicist Stefan Wallner from the University of Vienna.
The extent of nocturnal lighting has increased by almost ten percent annually over the past decade – much more than previously assumed, the researchers refer to current studies. In view of the global demographic change towards an increasingly urban way of life – 4.4 billion people already live in cities – most people are exposed to higher levels of nocturnal light exposure.
The negative effects of night light on night workers are well documented. They have a higher risk of cancer, cardiovascular disease, diabetes, high blood pressure, obesity and depression, among other things, the researchers write. “Because the circadian system plays a central role in human physiology, affecting almost all aspects of health, the effects of nocturnal light exposure and the associated disruption of this system are relevant for many people,” Schernhammer told APA. While there are still conditions that are relatively easy to measure during the night shift, the consequences of increasing outdoor lighting are more difficult to assess.
But here, too, a higher risk for the diseases mentioned and for sleep disorders has already been determined. More recent work has shown a connection between outdoor light with a high proportion of blue light and an increased risk of cancer. Reference is also made to studies during the Covid-19 pandemic that showed that people became infected more frequently, more severely and for longer if they suffered from sleep deprivation and/or worked at night or lived in areas that were brightly lit at night.
Indirect consequences for humans are also “virtually unavoidable, even if they are even more difficult to measure,” due to the pronounced effects of light pollution on flora and fauna, the work says. Insect die-offs associated with light pollution can be detrimental to health, “because insects control pests, help break down waste and pollinate more than a third of our food.”
Insect die-offs are just one of many far-reaching consequences of light pollution for most species. The effects on bird migration are well known: Anthropogenic light disorients the migratory birds, which mostly fly at night, which might collide with buildings or be distracted from suitable resting places. The effects of artificial lighting on sea turtles are well-documented: they avoid illuminated beaches for laying eggs, light disorients their hatchlings following hatching, leading to high mortality rates.
Other examples cited by the researchers: nocturnal mammal species reduce their activity in nocturnal light, while birds “get up” earlier; smaller fish congregate near light sources, making them easy prey: fireflies find it difficult to attract mates in artificial light, causing populations to shrink, and even trees are affected: if they grow near streetlights, they shed their leaves later inside year from.
The researchers are convinced that the increase in nocturnal lighting will lead to a loss in biodiversity and possible feedback effects, including the impairment of ecosystem services such as crop pollination. It is therefore of paramount importance to keep natural areas dark and limit light emissions.
“Every citizen should have the right to darkness and to high-quality, responsible outdoor lighting in order to improve their health and well-being and their social life,” emphasize the scientists. As positive examples, they point to countries such as the Czech Republic, France, Germany, South Korea and Slovenia, which have taken legal and political measures once morest light pollution.
Lighting adjustments might reduce the impact. These include shields that prevent light from being emitted in unwanted directions, time-limited and adaptive lighting, reducing the light intensity or adjusting the color composition. But you can also do something within your own four walls to reduce the negative effects of lighting, the researchers emphasize, citing, for example, switching to warm white light with a lower blue light component, as well as sensors and timers that switch off the light on the balcony, in the garden or on facades in the evening or dim.
In order to understand the causes of light pollution and take possible countermeasures, its extent must be measured – which is not so easy, emphasizes Stefan Wallner and his colleagues in one of the publications. There are a variety of devices and methods for examining artificial light at night – which makes it difficult to compare different observations.
Wallner also sees politics in Austria as having a role in effectively curbing light pollution: The recently overhauled ÖNORM on light emissions and the forthcoming light pollution law in Upper Austria are “important steps. A nationwide law on this will still be necessary to protect nature and the environment once morest artificial maximum light at night,” said the astrophysicist in a broadcast.
The fight once morest light pollution is not regarding turning off all the lights, but regarding a “balance between competing interests” and education, the researchers emphasize. This would reduce damage to human and environmental health, as well as energy wastage and carbon emissions. The scientists advocate doing away with prejudices such as “the brighter the better” and “well lit means brightly lit”. It’s more regarding “the right amount of light, the right kind of light, where and when it’s needed”.
(SERVICE – Internet: Impact on people: Impact on Species: Effects on Astronomy: Measurement of light pollution: Regulation of light pollution: http://dx.doi.org/10.1126/science.adh7723)
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