Most of our plastic waste is buried, incinerated or recycled at landfills – but up to 18% ends up in the area. Since plastic is not easily decomposable, it fragments into smaller and smaller pieces until the microplastics are small enough to sweep into the air.
This means that much of the plastic that is dumped into the sea and over land is broken down and spit out again, which poses potential risks to our ecosystems. And while there has been some progress in creating biodegradable polymers, the researchers warned that microplastics “will continue through the earth’s systems.”
From 2017 to 2019, the research team collected atmospheric microplastic data from the western United States and found that approximately 22,000 tons of microplastics are deposited in the United States annually.
In the US, the most important way is plastic being thrown into the air through road traffic. Car tires, brakes and even road surfaces contain plastic, which can be turned into microplastic that penetrates the atmosphere. The turbulence of cars on the road – the movement of tires, the braking process, the exhaust gases they emit – all help to move plastic onto the ground and send it skyward, according to the study.
It also happens in the ocean, where large clusters of debris form entire plastic islands. They are broken down into plastic particles that sit on the top layer of water, where they are thrown into the air by waves and wind.
There are different ways in which microplastics penetrate the atmosphere, in large cities by the wind and on farms by raw materials during agricultural processes.
Once they enter the atmosphere, plastic can stay in the air for up to six and a half days, according to the study. Within this time, “under the right conditions, plastic can be transported across the great oceans and between continents, either in one trip or by re-suspension across the oceans,” the study said.
The study said that the US, Europe, the Middle East, India and East Asia are hotspots for plastic deposition on land. Meanwhile, ocean plastic sources of aerospace are more prominent along the coast, including the U.S. West Coast, the Mediterranean, and South Australia. Dust and agricultural resources for microplastics are more prevalent in North Africa and Eurasia, while microplastics from road traffic worldwide make a major contribution to ‘heavily populated regions’.
“Inhalation of particles can be irritating to lung tissue and lead to serious diseases, but whether plastic is more or less toxic than other aerosols may not yet be well understood,” the study said. It added that further research is also needed to understand the impact of various factors, including population density and ocean circulation.
The researchers also called for better management of plastic waste.
“Our relative ignorance of the consequences, despite rapidly rising plastic concentrations in our environment, underscores the importance of improving plastic waste management or, indeed, capturing ocean plasticity and removing the system,” the study said.