The study, led by lighting technology expert Toivo Varjas, compared Tallinn with other cities in the Nordic region that bordered the sea and with a similar-sized population.

"Tallinn is one of these medium-sized cities. We don't have very many high-rise and congested cities, but we do have areas like the city center and some neighborhoods that are clearly visible from the sky," Varjas said on "Terevision" morning program.

He said light pollution not only stops us from seeing the stars but disturbs wildlife. It has also been linked with obesity, sleep disorders, nerve cell degeneration, and an increase in some cancers.

Lighting cities is essential but there should be limits, Varjas said.

"Light becomes pollution the moment you shine it into places you don't really want to shine it. If we want to drive a car, walk on foot, stroll in a park, we want to feel safe and have enough light. But it is reasonable that light does not shine where we do not want it to shine," he explained.

Satellite images seem to show that while Tallinn's light pollution gradually increased during the pandemic, in 2022 it shot up by a quarter from 57866.8 nW/cm2/sr to 72759.6 nW/cm2/sr.

It is also thought this assessment may be on the conservative side due to the type of satellites used for observations.

Contributing factors in areas with a higher level of light pollution include traffic and population density, as well as institutions open at night and their outdoor areas. Construction and renovation also play a role.

The rising number of advertising screens is having an impact too. "That's where LED screens come in. All the ads that are prominent. Whereas we used to illuminate them from the outside onto the surface, now we see a series of illuminated displays on the outside, dazzling drivers, the surrounding area and the facades of buildings," Varjas said.

To reduce light pollution, the expert suggested cutting the level of brightness during the night or turning devices off completely. Switching lighting solutions and advertising lights on the side of buildings could reduce the capital's level of light by 15 percent.

Districts that, historically, have had a lower level of light pollution, such as Nõmme and Põhja-Tallinn, have begun to be affected by the construction of new street lights and new real estate developments. But, at the same time, areas of greenery – such as tall trees – prevent the light from reflecting upwards. This is something urban planners can consider incorporating in the future.

The study showed that Tallinn's light pollution has grown three times faster than Turku in Finland and Gothenburg in Sweden.

TalTech researchers said the quality of urban planning in Tallinn in terms of light pollution currently leaves much to be desired. One way to limit this would be to keep an eye on how many new apartment buildings are built in garden cities, developments with a lot of greenery. Otherwise, light pollution in the city center will also spread to them.

Another area for improvement could be reducing lighting on roads, beach promenades, and streetlights. Additionally, the port and Ülemiste areas were clearly visible in the images.

"City promenades, some places where people don't move, could at least be dimmed lower," said Varjas. 

Alternatively, these lights could triggered by motion sensors. Turning them off completely would reduce brightness by more than 50 times.

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