Most of our plastic waste is buried in landfills, incinerated or recycled, but up to 18% ends up in the environment. Because plastic cannot decompose easily, it shatters into smaller and smaller pieces until the microplastics are small enough to be blown into the air.
This means that much of the plastic that is dumped into the sea and all over the land decomposes and spits 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 to circulate through terrestrial systems.”
The research team collected atmospheric microplastic data from the western United States from 2017 to 2019 and found that it is estimated that 22,000 tons of microplastics are deposited in the U.S. each year.
In the US, the main way to throw plastics into the air is through road traffic. Tires, brakes and even road surfaces contain plastic, which can wear on microplastics that enter the atmosphere. According to the study, the turbulence of cars on the road (the movement of the tires, the braking process, the exhaust they emit) help to produce plastic on the ground and send it to the sky.
This also happens in the ocean, where large groups of waste form entire plastic islands. They break down into plastic particles that settle in the top layer of water, where waves and wind throw them into the air.
There are other ways to get into the atmosphere in microplastics, in big cities by wind and on farms through soil dust during agricultural processes.
Once they enter the atmosphere, plastics can remain in the air for up to six and a half days, according to the study. Within that timeframe, “under the right conditions, plastics can be transported across major oceans and between continents, either on a single trip or by resuspension over the oceans,” the study said.
The United States, Europe, the Middle East, India and East Asia are hot spots for plastic deposition on the ground, according to the study. Meanwhile, airborne plastic sources of air are most important on the coasts, including the west coast of the United States, the Mediterranean, and southern Australia. Sources of dust and agriculture for microplastics are more common in North Africa and Eurasia, while microplastics from road traffic are the main contributors to “highly populated regions” around the world.
“Inhalation of particles can irritate lung tissue and cause serious illness, but it is still not well understood whether plastics are more or less toxic than other aerosols.” He added that more research is also needed to understand the impact of different factors, including population density and ocean circulation.
The researchers also called for better management of plastic waste.
“Our relative ignorance of the consequences despite the rapid increase in plastic concentrations in our environment highlights the importance of improving the management of plastic waste or, in fact, capturing ocean plastics and removing them from the system,” he said. say the study.