Plastic from European cities reaches Zeppelin Observatory

Every 14 days, a filter is changed in a sampler attached to the railing of the Zeppelin Observatory, 472 metres up Zeppelin Mountain above Ny-Ålesund. Beside it stands a large metal bucket that collects everything that falls from the sky, snow included. Both have been there since autumn 2021, and both are looking for plastic.

The national results for 2025 came out on 4 November. The Norwegian Environment Agency measures microplastic falling from the air at three stations: Zeppelin, Birkenes in Agder and Sofienbergparken in Oslo. The Oslo station measured about 30 times the Svalbard average and about 13 times the level at Birkenes.

The observatory

The observatory opened in September 1989 as part of the Ny-Ålesund research station. The first building had water leaks, poor insulation and heavier snow loads than expected, and the instruments needed more room. It was rebuilt in 1999 and inaugurated on 2 May 2000, according to a 2022 study by NILU researchers in the journal Atmospheric Chemistry and Physics.

The Climate and Environmental Research Institute NILU has the scientific responsibility for the observatory. The Norwegian Polar Institute handles its daily technical maintenance. NILU says the site lies "in an undisturbed arctic environment, far from major sources of pollution". Besides microplastic, the station measures greenhouse gases, ozone, aerosols, mercury and other pollutants, and its data go to international networks that track the atmosphere.

How plastic is caught without plastic

The two samplers do different jobs. The active sampler draws air through filters that collect all particles larger than 10 micrometres. It measures plastic floating in the air. The passive sampler, the bucket, measures how much falls to the ground, including in rain and snow.

The equipment cannot itself contain plastic. "We can't take microplastic samples with plastic equipment," NILU senior scientist Dorte Herzke said in 2023. The samplers are adapted from an earlier NILU design, with all the plastic components replaced with metal. The filter holder closes as soon as it is removed, so the sample is not contaminated on its way to the laboratory.

In the laboratory, the filters are heated to 600 degrees without oxygen. The plastic does not burn: its polymer structure breaks apart, a process called pyrolysis. The fragments are then analysed with a mass spectrometer.

Monitoring began in 2021 as a pilot of six measurements over three months on Svalbard and at Birkenes. It now runs all year. In 2025 each station took 12 samples, each covering 14 days. The work is part of Mikronor, the national microplastic monitoring programme led by the Norwegian Institute for Water Research (NIVA) for the Environment Agency. "Norway is the only country in the world that has permanent monitoring of microplastics in the air," said Natascha Schmidt, a senior scientist at NILU.

What the numbers measure

The Mikronor 2025 report gives Zeppelin's own figures. Microplastic falling to the ground averaged 18 micrograms per square metre per day, against 42 at Birkenes and 550 at Sofienbergparken in Oslo. The highest sample at Zeppelin, 75, was taken in March; the lowest, 3, in January and late August. Half of all analyses at Zeppelin were below the detection limit.

The figures measure plastic falling to the ground at one station, not the air people breathe in Longyearbyen or Ny-Ålesund.

Where the plastic comes from

In August, NILU reported that high concentrations at the observatory "originate from urban areas in Europe", and that dispersion models point to Central and Southern Europe as the main sources. The findings are published in the paper "Airborne microplastics on the move: Urban Europe as a source to remote regions".

The paper, by Dorte Herzke and seven colleagues, uses samples from 2022 and 2023. The air arriving at Zeppelin and Birkenes was traced 50 days back with the dispersion model FLEXPART. When the samples were high, the air had come from Central and Southern Europe and from the Atlantic west of the Iberian Peninsula. When they were low, it had come from Eastern Europe or from the open Atlantic between 35 and 40 degrees north, regions where far less plastic enters the air.

Road dust was the largest modelled source at both stations, followed by mineral dust blown up from soil and plastic lifted from the sea in spray. In the air at Zeppelin, polyvinyl chloride (PVC) and PET were the main plastics found, with polypropylene a minor part. Neither remote station showed a seasonal pattern; Oslo did, with the change to winter tyres.

"Everything that is transported by air is very fast," Herzke said. Particles are sometimes carried many hundreds of miles within days, according to NILU, and the transport is most efficient in autumn and winter. At Zeppelin, polypropylene and PET were the plastics found most often. Tyre wear particles were detected in 2 of the 12 samples, in March and November; in Oslo they made up about 75 per cent of the microplastic.

The report links the lowest sample, from late August, to air that came over open ocean, and the higher samples to air from larger or continental areas.

In January 2023 the Environment Agency reported that concentrations in southern Norway were four times those on Svalbard, probably because of more precipitation and continental air masses.