Microplastics in Clothing: What They Are and What You Can Do About It

Every time you wash a synthetic garment - a polyester fleece, a nylon activewear set, a fast-fashion staple - you're releasing microplastics into the water supply. Not metaphorically. Literally, by the hundreds of thousands, per load.

This isn't a distant environmental problem. It's happening in your laundry room, right now.

Here's what's actually going on - and what you can do about it.

What Are Microplastics?

Microplastics are fragments of plastic smaller than 5 millimetres - roughly the width of a pencil tip. They're too small to be filtered by most wastewater treatment plants, which means they flow directly into rivers, lakes, and oceans after leaving your washing machine.

A 2020 study estimated that 9.25 to 15.86 million tonnes of microplastics currently sit on the ocean floor. Of all the sources contributing to that number, synthetic textile fibres are the single largest - responsible for approximately 35% of all microplastic ocean pollution, or around 2.2 million tonnes of microfibre every year.

How Does Laundry Release Microplastics?

Synthetic fabrics - polyester, nylon, acrylic, spandex - are made from petroleum-based filaments twisted together into yarn. When a garment made from these fibres goes through a wash cycle, the combination of water, friction, and detergent causes those filaments to break down and shed.

A single load of synthetic laundry releases approximately 750,000 microplastic particles into the wastewater system.

The amount shed depends on several factors: the tightness of the weave (looser = more shedding), the age of the garment, water temperature, and detergent type. Synthetic fleece - sold widely, including by brands that market themselves as sustainable - is one of the worst offenders.

Why Should You Care Beyond the Ocean?

The ocean impact is serious. But microplastics have also entered the human food chain.

They've been detected in bottled water, tap water, beer, sea salt, and seafood. Scientists are actively studying the health implications of ingesting plastic particles - including potential effects on the immune system and childhood development. The research is still emerging, and that uncertainty itself is the concern.

Currently, there are no standardised requirements for microplastic filtration from bodies like ANSI or NSF International, which means consumer products like water filters aren't certified to remove them.

Meanwhile, global production of synthetic textiles is projected to triple by 2050.

What You Can Do: Three Practical Solutions

1. Choose natural fibre clothing

This is the most direct solution - and the one with the most co-benefits.

Natural fibres like merino wool don't shed microplastics. Full stop. When a merino garment breaks down, it returns to the earth as a natural protein fibre, not petroleum particles.

Merino wool also happens to be naturally temperature-regulating, moisture-wicking, antimicrobial, and odour-resistant - which means it requires washing far less frequently than synthetic alternatives. That combination of no microplastic shedding and fewer wash cycles makes it genuinely one of the most low-impact choices you can make for your wardrobe.

At Nui, we've worked with merino since we were founded in New Zealand in 2003 Our merino is rigorously sourced and free from synthetic chemical treatments - because even "100% natural" labels can hide up to 30% chemical additives by weight, applied for stain resistance or water repellency. Transparency matters.

2. Wash less, wash full

Not everyone can immediately replace their synthetic wardrobe - that's a realistic constraint. But you can reduce the microplastics released right now by changing how you wash.

Air garments out between wears rather than defaulting to the laundry hamper. Spot clean where possible. When you do wash, always run full loads - a 2020 study from Newcastle Innovation Center and Northumbria University found that going from small to large loads roughly halved the number of microfibres released, because fuller machines create less friction between garments.

Cold, shorter cycles also reduce shedding.

3. Use a laundry microfibre filter (with realistic expectations)

Microfibre filters - devices that attach to your washing machine's outlet hose - can capture a portion of fibres before they enter the wastewater system. Several brands claim significant reduction rates.

The honest caveat: there's currently no standardised testing methodology for these devices, so results vary depending on machine type, water temperature, garment type, and detergent. And once the filter is full, the captured microfibres still need to be disposed of in landfill - they can't be recycled.

Think of it as a partial measure, not a complete solution.

The Bigger Picture

The microplastic problem won't be solved by any single purchase. But the choices that compound over time - building a wardrobe from durable natural fibres, washing thoughtfully, and buying less, more intentionally - add up in real and measurable ways.

A well-made merino piece, worn season after season, washed a fraction as often as a synthetic equivalent, produces a fundamentally different environmental outcome than a fast-fashion cycle of cheap synthetics replaced every few months.

That's the case for natural fibres - not as an idealistic statement, but as a practical calculation.

Browse Nui's merino collection for adults and kids — made from certified, responsibly sourced New Zealand merino, built to last.