Microplastics floating in the atmosphere: Circulating on a global scale

 　　Large amounts of microplastic debris are floating in Earth's atmosphere and can even travel across continents as the air moves, a new study says. Researchers say this environmental problem could become more serious in the future and could have serious implications for human health.

　　At present, there is no precise definition of microplastics in the academic community, but it is generally believed that plastic fibers, particles or films with a size of less than 5 mm can be regarded as microplastics. Previous research has shown that microplastic particles can be found in the ocean, bottled water, and even in our feces, but until now, scientists still know very little about the atmospheric part of the so-called "microplastic cycle."

　　The new study points out that thousands of tons of microplastics already exist in Earth's atmosphere, the most notable source of which is roads. Computer models also reveal how microplastic particles are transported over long distances across the globe, leaving nowhere safe from pollution. The findings, the researchers say, once again show that microplastics are one of the most pressing environmental issues of our time.

　　"Microplastics destroy nearly all ecosystems, let alone human health," said Janice Barani, an environmental scientist at Utah State University and lead author of the study. "We are just beginning to understand the effects of microplastic pollution. The extent of it, and its impact is unknown.”

　　In terms of importance, the microplastics problem can be comparable to, and to some extent, intertwined with, climate change. "Because plastic is a product of fossil fuels," Janice said.

　　Entering the Atmosphere

　　To figure out how microplastics enter and travel through the atmosphere, Janice and colleagues measured airborne particle fallout at multiple sites in the western United States over a 14-month period. Based on the measurements, they estimate that there are about 1,000 tons of microplastics in the atmosphere over the western United States.

　　Janice said the team was "very shocked" by the amount of microplastics they found. Researchers had previously expected cities to be the largest source of microplastic pollution in the atmosphere, but an analysis of these fallout particles showed that roads were the biggest source: 84% of the microplastics in the atmosphere come from roads.

　　"It makes sense given that plastic, like dust, needs some kind of physical action to get into the atmosphere," Janice said. "Roads, and the cars on them - which may be more important - provide the Mechanical energy transported by microplastic particles into the atmosphere.”

　　Other sources of microplastics in the atmosphere include oceans (11%) and agricultural soil dust (5%), both of which are linked to the effects of strong winds. However, the researchers suspect that the levels of pollution from the three sources are likely not the same in other parts of the world. 　　Recycling

　　the data collected around the globe , the researchers built computer models to try to figure out how microplastics are transported around the globe, and which regions are likely to be hotspots with the highest levels of microplastics, such as Europe, East Asia, the Middle East, India and the United States

Wait. "The atmosphere is one of the reasons why microplastics are so prevalent," Janice said. "The atmosphere can transport microplastics to different places, across continents, to very remote places that are not normally polluted by humans." The

　　researchers It was also found that microplastic particles can remain in the air for periods ranging from 1 hour to 6.5 days, an upper limit sufficient for transcontinental transport. It also means that even remote places like Antarctica without direct sources of microplastics are at risk of contamination. "No one is immune to this source of pollution," Janice said. "We can ship garbage to other countries, but these [microplastics] will still come back to haunt us."

　　Previous studies have pointed out that the ocean has become a Microplastics are hardest hit by microplastic pollution, from offshore to oceans, from the poles to the equator, from the ocean surface to seafloor sediments, and even the most remote polar glaciers have detected microplastics. It can be said that microplastics have spread throughout the marine system. Microplastics are also found in our daily consumption of shellfish, fish and other foods, as well as in drinking water.

　　Next research The problem of microplastics in the

　　atmosphere may become more serious. "It takes time for plastic to break down into the tiny pieces we see in the atmosphere," Janice said. "The problem is compounded by our lack of effective ways to deal with plastic waste, and there may be more in the future. A lot of microplastics get into the environment and then into the atmosphere."

　　Janice pointed out that the research to understand the global movement patterns and processes of microplastics is just beginning, and the next important research direction is to understand how microplastics in the air affect human health. "Inhalation of any particulate matter can have negative health effects," she said, "but as of now, we don't know if microplastics are more harmful than other gas aerosols."