The air over the Arctic and Antarctic may look perfectly clean, but scientists say it still contains tiny particles of dust, smoke and sea salt that can affect weather and climate.
Researchers from the Institute of Geophysics of the Polish Academy of Sciences and international partners analysed these particles, known as aerosols, in a study published in Atmosferic Chemistry and Physics.
They also developed ways to measure them even during the long polar night, when the Sun does not rise for weeks.
Aerosols are too small to see, but they change how light travels through the air — much like a dirty window makes things look less clear.
Scientists measure this using a scale called aerosol optical depth (AOD). Higher values mean more particles and hazier air.
One challenge is that most traditional measurements rely on sunlight. In polar regions, this creates gaps in data during winter. To solve this, researchers began using the Moon — and sometimes even stars — as a light source, allowing them to track air conditions all year round.
The study combined data from 26 research stations — 15 in the Arctic and 11 in Antarctica — up to the end of 2024. This included the Polish Hornsund station in Svalbard.
With this long record, scientists were able to see both current conditions and how they are changing over time.
The findings show that Arctic air is not always as clean as it seems. In winter and early spring, a phenomenon called Arctic haze appears, when pollution from faraway regions drifts into the area and makes the air more polluted.
The study shows that particles can travel thousands of kilometres, reaching places with little or no local pollution.
Researchers also highlight the growing impact of wildfire smoke, which can quickly worsen air quality even if industrial emissions are falling.
There are also differences between the two polar regions. In Antarctica, air near the coast is usually less clear than further inland, likely because sea salt from the ocean gets into the air more easily.
Trends over time are mixed. Some locations show cleaner air, while others show increasing pollution.
Scientists say these changes depend on many factors, including wind patterns, seasons and sources of pollution.
They add that continuous monitoring — including during the dark winter months — is key to understanding how the atmosphere in these remote regions is changing. (PAP)
PAP - Science in Poland
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