Microplastics. They’re in the soil; they’re in the ocean; and they’re even in the air, poised to invade our respiratory systems and to harm our health. But how, exactly, do they make their way into the atmosphere?
Some studies have suggested that these tiny pieces of plastic — at most around 5 millimeters across — take to the air from the ocean. Ocean spray shoots them into the atmosphere, these studies say, positioning these minuscule pollutants to enter our bodies when we breathe. But a new paper published in npj Climate and Atmospheric Science suggests that the ocean may absorb more airborne microplastics than it introduces.
“The ocean functions more as a sink than a source,” the authors stated in the study. “This challenges the previous view of the ocean as the primary atmospheric microplastic source, urging a reassessment of pollution mitigation strategies.”
Read More: How Microplastics Sneak Into Our Bodies
A Source or a Sink of Airborne Microplastics?
Most microplastics are made on land, where larger plastic debris degrades into tinier and tinier pieces. From there, these small particles of plastic are washed into waterways and transported to the ocean, where they are then shot into the air. Indeed, some studies have suggested that sea spray and waves send microplastics into the atmosphere by way of the air bubbles that they create.
In these studies, observations of airborne microplastics around the world seemed to indicate that the ocean introduced millions (or even billions) of kilograms of tiny pollutants into the air each year. While subsequent science lowered that estimate to thousands of kilograms, the authors of the npj Climate and Atmospheric Science study sought to take another look at the ocean and its impact on airborne microplastics to determine whether the sea is actually as significant a source of the pollution in the air as these previous papers say.
Creating a chemical transport model (a computer simulation that mimics the movement of atmospheric components in and from the air), the authors of the new study saw that the ocean is not a substantial source of atmospheric microplastics but is, instead, a substantial sink.
“Although the ocean contributes only about 0.008 percent as a source of atmospheric microplastics, it plays a crucial role as a sink,” the study authors wrote. In fact, they found that the ocean actually absorbs about 15 percent of atmospheric microplastics.
The study authors also found that the size of microplastic particles modulates their movement through the world’s atmosphere. The more sizable the particle, the more quickly it settles, with some of the smallest microplastics staying airborne for as long as a year, floating all around the world, from one part of the globe to another.
Read More: Microplastics Are Everywhere. What Are They Doing to Our Health?
An Airborne Threat
The introduction of tiny plastic particles into the atmosphere is an important process to untangle since their presence poses a significant threat to our health — particularly our respiratory health. According to a 2024 review of some 3,000 studies in Environmental Science & Technology, these threats include infertility, pulmonary inflammation, and poor pulmonary function, the second of which is tied to an increased risk of lung cancer.
Ultimately, the npj Climate and Atmospheric Science study shifts the focus from oceanic sources of airborne microplastics to terrestrial ones, suggesting that it is the creation of microplastics on land that future mitigation strategies should address first and foremost.
“Effective mitigation of microplastic-related risks for human health and ecosystems hinges on a comprehensive understanding of atmospheric microplastic dynamics,” the study authors concluded in their study, perhaps pointing the way to a future with fewer microplastics floating around.
Read More: Our Brains Are Soaking Up Microplastics More Than Other Organs
Article Sources
Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
NPJ Climate and Atmospheric Science. Global Atmospheric Distribution of Microplastics with Evidence of Low Oceanic Emissions
Max Planck Institute for Meteorology. Airborne Microplastics: Where Do They Come From, Where Do They Go?
Environmental Science & Technology. Effects of Microplastic Exposure on Human Digestive, Reproductive, and Respiratory Health: A Rapid Systematic Review
Sam Walters is a journalist covering archaeology, paleontology, ecology, and evolution for Discover, along with an assortment of other topics. Before joining the Discover team as an assistant editor in 2022, Sam studied journalism at Northwestern University in Evanston, Illinois.
