Pollution

Microplastics spiral around the globe travelling through the air

Plastic pollution is airborne too. Microplastics are being carried across continents by the wind, as a recent study reveals.

The presence of microplastics in the world’s oceans is an issue that has gained increasing attention since 2004, when the term was coined by Richard Thompson, director of the University of Plymouth’s Marine Institute in the UK. But marine environments aren’t the only habitats in which microscopic plastic fragments circulate, as these are also found in the air and terrestrial ecosystems.

ocean plastics beach pollution
The issue of ocean plastic has received increasing attention, but other sources of plastic pollution threaten the environment and human health as well

A new study conducted by scientists from Cornell University and Utah State University in the United States shows that microplastics are being carried via air just like chemical elements such as calcium, carbon, hydrogen and oxygen, which cycle across the Earth via what are known as global biogeochemical cycles. This phenomenon is leading to airborne plastic pollution, a cause for concern as the accumulation of plastics in the atmosphere may have adverse impacts on human health.

The “plastification” of our planet

The US-based National Oceanic and Atmospheric Administration (NOAA) and the European Chemicals Agency (ECHA) define microplastics as pieces of plastic less than 5 millimetres long. These fragments are classified into primary and secondary types.

Microbeads, small pieces of plastic employed as exfoliating agents in personal care products, and other purposely manufactured microplastics belong to the first category. Microplastics that derive from the breakdown of larger pieces of plastic waste are instead defined as secondary microplastics, whose release is caused by the composition of plastic itself combined with waste mismanagement.

Worldwide plastic pollution, microplastics
400 million tonnes of plastic are produced worldwide each year © Dan Kitwood/Getty Images

Conventional modern plastic is derived from fossil fuel-based chemicals and as such, it degrades slowly, allowing its remnants to linger for up to hundreds of years. With a yearly plastic production of 400 million tonnes and recycling rate of about 9 per cent worldwide, a significant amount of microplastics builds up on our planet every year.

A spiral of microplastics

The team behind the airborne microplastic research published in the journal Proceedings of the National Academy of Sciences used more than 300 samples of airborne microplastics collected over 14 months from 11 sites across the western United States. Its goal was to elaborate a model of airborne plastic pollution and find the most likely sources of atmospheric plastic.

microplastics in the air
Airborne microplastics travel the globe © Ingimage

The researchers estimate that every year around 22,000 tonnes of microplastics are being deposited over the US, where atmospheric microplastics come primarily from secondary re-emission sources. Among these, 84 per cent come from road dust, the most significant source of this pollution. Oceans are estimated to be the second most significant contributor, accounting for about 10 per cent of airborne plastics in the US, while 5 per cent comes from agricultural soil dust.

The researchers’ model also shows that smaller microplastics could remain in the air for up to six and a half days. Under the right conditions, this is enough time for atmospheric currents to transport them across continents, causing microplastics to build up even in unexpected regions with no direct sources of plastic, such as Antarctica.

As plastic production is increasing at a rate of around 4 per cent per year, this study highlights the need to better understand the consequences of airborne microplastics for the sake of ecosystems and human health as well as the urgency of creating more efficient plastic waste management systems.

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