From Mount Everest to the Mariana Trench, microplastics are everywhere, even at high altitudes in the Earth’s troposphere, where wind speeds allow them to travel vast distances, a study found on Tuesday.
Microplastics are tiny fragments – measuring less than 5 millimeters – that come from packaging, clothing, vehicles and other sources and have been detected on land, in water and in the air.
Scientists from the French national research institute CNRS sampled the air at an altitude of 2,877 meters at the Pic du Midi observatory in the French Pyrenees, a “clean station” due to the limited influence that exert on it the local climate and environment.
There, they tested 10,000 cubic meters of air per week between June and October 2017 and found that all samples contained microplastics.
Using meteorological data, they calculated the trajectories of different air masses preceding each sample and discovered sources as far away as North Africa and North America.
Lead author of the study, Steve Allen, of Dalhousie University in Canada, told AFP the particles were able to travel such distances because they could reach great altitudes.
“Once it hits the troposphere, it’s like a super-fast highway,” he said.
Research also indicates sources of microplastics in the Mediterranean Sea and the Atlantic Ocean.
“The marine source is the most interesting,” Allen said.
“The plastic leaving the ocean in the air this high – it shows that there is no possible sink for this plastic,” he said.
“It just moves around and around in an indefinite cycle.”
While the amounts of microplastics in the samples from the Pic du Midi do not pose a health risk, study co-author Deonie Allen notes that the particles are small enough that humans can breathe them in.
And she says their presence in an area considered to be protected and far from sources of pollution should be sobering.
“It calls into question the relationship we have with plastic,” she said, adding that the problem is global.
Allen said it also shows that disposing of plastic by sending it overseas is a flawed strategy.
“It will come back to you,” he said.