Microplastics & Polyester
Every time you wash your favourite hoodie, it sheds tiny bits of plastic into the ocean. By the end of this lesson, you'll understand exactly why — and what's actually worth doing about it.
What polyester actually is
About 60% of clothing made today is polyester. Polyester is a kind of plastic. Specifically, it's a polymer made from petroleum — the same crude oil used to make gasoline and water bottles.
Polyester became popular because it's cheap, strong, dries fast, and doesn't wrinkle. The downside is that it does what plastics always do: it doesn't biodegrade. A polyester t-shirt thrown in a landfill in 2025 will still be there in the year 2225.
Nylon, acrylic, and elastane (spandex) are also plastics. If your label says any of those, plus polyester, your clothes are made of oil. Worldwide, the textile industry uses around 70 million tonnes of plastic fibre a year — more than all the plastic bottles produced annually.
Microplastics and your washing machine
Every wash, synthetic clothes shed tiny fibres — invisible bits of plastic less than 5mm long. These are called microplastics, or more specifically 'microfibres.'
A 2016 study by Plymouth University found that a single 6kg load of synthetic laundry can release around 700,000 microfibres. They're too small for most washing machine filters and most water treatment plants. So they wash straight into rivers and oceans.
Microplastics have been found in: deep-sea fish, Arctic snow, human blood, human placentas, drinking water, and rain. Globally, an estimated 35% of all ocean microplastics come from washing synthetic clothes — making your laundry one of the largest plastic-pollution sources on Earth.
What actually helps
You don't have to throw out all your polyester. (That would actually make it worse.) You just need to slow the shedding. Things that work:
- Wash less. Wear hoodies and jeans more times between washes. - Wash colder. Cold water sheds far fewer fibres than hot. - Wash full loads. Less rubbing means less shedding. - Use a Guppyfriend bag or a Cora Ball — laundry tools designed to catch microfibres. - Air-dry. Tumble dryers are huge fibre-shedders, and the fibres go straight into the air.
When you do buy new clothes, look for natural fibres — cotton, linen, wool, hemp — for items you'll wash often (t-shirts, underwear). Save synthetics for items you wash rarely (raincoats, athletic gear).
Recycled polyester: progress or excuse?
Many brands now sell 'recycled polyester' (rPET), often made from old plastic water bottles. It sounds great. The reality is more complicated.
Good news: rPET uses about 30–50% less energy than virgin polyester and keeps bottles out of landfill — for one extra use.
Bad news: Once a bottle becomes a t-shirt, it's much harder to recycle again. Bottle-to-bottle is a closed loop. Bottle-to-shirt is usually a one-way trip to landfill. And rPET still sheds microplastics just like virgin polyester does.
So recycled polyester is better than virgin polyester — but it's not the answer. The real answer is using less synthetic material to begin with.
Key takeaways
- Polyester is plastic — about 60% of all clothing today is made from petroleum-based fibres.
- A single 6kg load of synthetic laundry can shed ~700,000 microfibres.
- About 35% of ocean microplastics come from synthetic clothes washing.
- Wash less, wash cold, wash full loads, and use a Guppyfriend bag to cut shedding.
- Recycled polyester is better than virgin — but it still sheds microplastics and can't usually be recycled again.
Try this
Label hunt
Open your wardrobe. Pick 10 items at random and read the labels. Count how many contain polyester, nylon, acrylic, or elastane. Calculate the percentage. Most homes are 60–80% synthetic without knowing it. Bonus: which item surprised you most?
The cold wash experiment
For two weeks, wash all your laundry on cold (or 30°C / 86°F). Track whether anything got noticeably less clean. (Spoiler: it almost never does.) Cold wash can cut microfibre shedding by half AND saves a huge amount of energy — around 90% of a wash cycle's energy goes to heating water.
Make a microplastic explainer
Create a short poster, comic, or video (1 minute max) explaining how microplastics get from your washing machine to a fish to a human. You can use simple drawings or stop-motion. Share it with one friend or family member. Teaching is the fastest way to remember something yourself.
About how many microfibres can a single 6kg load of synthetic laundry release?
A 2016 Plymouth University study estimated around 700,000 microfibres per 6kg load of synthetic clothes. They're too small for most washing machine filters and most water treatment plants, so they end up in rivers and oceans. Washing colder, less often, and with a microfibre-catching bag are the main ways to cut shedding.