Why don’t microplastics keep breaking down? © Getty Images

Why don’t microplastics keep breaking down?

Microplastics do keep breaking down but the time it takes depends on multiple factors.

It’s all about timescale. Microplastics do keep breaking down, but as the pieces get smaller, the decomposition rate slows. Most microplastics form when bigger bits of plastic break down in the environment, aided by sunlight, oxygen and friction. Microbes can also play a part in decomposition, depending on the type of plastic.

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With all of these processes, the microplastics can continue to break down to form nanoplastics, which have diameters below one micrometre or one-thousandth of a millimetre. These are invisible to the naked eye and hard to detect using analytical kit, which is perhaps why we don’t hear about them so much.

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Asked by: Charlotte Lowe, St Austell

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