As much as 58% of the Polish population has no chance of observing the Milky Way, and for 20% of the country’s population, the night sky is so bright that vision remains in daytime mode throughout the day, according to experts.
The report on light pollution was published by the Center for Space Research of the Polish Academy of Sciences and the Light Pollution Think Tank.
According to the study, the natural night sky over Poland no longer exists. The brightest urban location is the Defilad Square in Warsaw, but even brighter are the greenhouse areas. Excessive light disrupts sleep and metabolism, harming humans, animals, and plants. 58% of the Polish population has no chance of seeing the Milky Way, and for 20% of the country’s population, the night sky is so bright that vision remains in daytime mode throughout the day.
Satellite analyses revealed that the territory of Poland brightened by at least 6% in 2022 compared to the previous decade. It was the brightest year in the history of observations. Most light was emitted from large cities. Only five of them—Warsaw, Łódź, Kraków, Gdańsk, and Poznań—accounted for 10% of all light sent from Poland into space. Greenhouses emitted light most intensely. Some of them appeared several times brighter on satellite maps than the area around Defilad Square in Warsaw, the brightest urban location in Poland.
“In 2022, the natural night sky over Poland no longer existed. The closest to the ideal was only over the Bieszczady Mountains—only 6% brighter than the light pollution-free sky. Over large cities, this brightening was already several thousand percent. In the case of cities like Warsaw, Krakow, or Poznań, in 2022, the sky was always brighter than it should be after dark. True night never arrived in these cities,” explained Dr. Andrzej Kotarba from the Center for Space Research of the Polish Academy of Sciences, the main editor of the report.
According to Agnieszka Machnowska, an expert from the POLARIS Association, light pollution results from thoughtless and excessive illumination of objects. “We want to light roads and streets to make them safe to use after dark. We also use light for decorating buildings and illuminating advertisements. The problem arises when we install lighting that is too intense, too white, and directs the light stream to entirely unnecessary places: facades and interiors of buildings, lawns, tree canopies, and even straight into the sky,” explained the co-author of the report.
As the report indicates, Polish legislation does not consider excessive light emission as pollution, unlike noise or smog. However, scientists emphasize that an excess of light in the environment affects the functioning of plants and animals, as well as humans. “Exposure to light at night disrupts our internal biological clock, leading to disturbances in sleep and metabolism, some of the most common civilization diseases,” listed Dr. Tomasz Ściężor from the Krakow University of Technology, a co-author of the report.
The report aims to draw attention to the growing problem of light pollution and provide scientifically supported arguments for discussions on the implementation of a national sustainable lighting policy.
“Night lighting is one of the achievements of civilization. Combating light pollution does not mean giving it up and turning off all lights. It’s about using light rationally and not depriving ourselves and others of the opportunity for a healthy life in a healthy environment. In the process, we will also save the view of the night sky. It may turn out that in some time, the sky after dark will be so bright that we won’t see any stars on Christmas Eve,” Dr. Kotarba concluded.
The report was prepared by employees of Polish universities, research institutes, and non-governmental organizations working to reduce light pollution.