What are microplastics and nanoplastics?

Microplastics are pieces of plastic smaller than 5 millimetres. Nanoplastics are the smallest of these, usually defined as smaller than one micrometre: about a hundredth the width of a human hair.

Where they come from

• Breakdown of larger plastic. Bottles, bags and packaging fragment over time.
• Wear in use. Chopping boards, non-stick coatings, tyres and synthetic clothes shed particles as they're used.
• Heat. Warming food or drink in plastic speeds up release.
• Made small on purpose. Microbeads in rinse-off cosmetics, now banned in the UK, were one example.

How they reach people

Mostly through food and drink, and through the air we breathe indoors, where synthetic fibres from clothes and furnishings settle as dust.

Why the size matters

Larger particles mostly pass through the body. Smaller ones, especially nanoplastics, are harder to measure and more likely to be taken up by tissues, which is why researchers are focusing on them now.

What you can do

You can't avoid microplastics entirely, but you can cut the biggest sources in your home. Our Swap Priority score ranks swaps by exactly this: how directly and how often plastic touches your food, drink and skin. The free Home Plastic Audit shows your top three.