The scientists said they were shocked by the sheer number of particles they found: more than 10,000 of them per litre in the Arctic.
It means that even there, people are likely to be breathing in microplastics from the air - though the health implications remain unclear.
The region is often seen as one of the world's last pristine environments.
A German-Swiss team of researchers has published the work in the journal Science Advances.
The scientists also found rubber particles and fibres in the snow.