Samples were taken at the Pic du Midi observatory, perched at 2,877 meters in the French Pyrenees.
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Microplastics can be transported between continents by high winds. This is highlighted by a study published on Tuesday, December 21 in the journal Nature Communications (link in English). These residues of a few millimeters at most, resulting for example from the deterioration of packaging or washing clothes, are of increasing concern to researchers. Researchers from the CNRS, the Université Grenoble Alpes 2 and the University of Strathclyde (Scotland, United Kingdom) looked for them in the air for this study. “pure”, aloft above the clouds. Samples were taken at the Pic du Midi observatory, perched at 2,877 meters in the Hautes-Pyrénées, between June and October 2017, with a pump sucking 10,000 m3 of air per week.
All were found to contain microplastics. In quantities without immediate risk to health, but significant in a presumed preserved area, where “one cannot easily attribute” this pollution has no local origin, write the researchers. To understand its origin, they therefore calculated the trajectory of the different air masses sampled over the seven days preceding the samples. Result: the pollutants originate in particular from the northwest of the African continent, passing over the Mediterranean, but also from North America or the Atlantic Ocean.
These data confirm an intercontinental route, because the atmospheric zone studied, the free troposphere, acts as “a hyper-fast lane” over very large distances for particles, says Steve Allen, lead author of the study. For the researcher, it is the marine origin of a part of these particles which constitutes the most salient teaching of the study. “That plastic is being pulled from the ocean to such altitudes shows that there is no possible storage sink, it goes around in circles in a perpetual cycle. It shows that you can’t just send plastic abroad, because it will come back to you “ in another form. Especially since some of the particles analyzed, of the order of a micron, “are of a size that we can breathe”, adds Deonie Allen, also author of the study. These results “show that it is indeed a global problem”, adds the researcher.