Every step outdoors can leave behind microplastics you’ll eventually absorb.

I spent many summers on Long Island when it was still a forest wonderland of beautiful trees, lush blueberries, huckleberry bushes, blackberry brambles, and streams full of frogs and small box turtles. We ran with simple sandals, Keds, or bare feet. No one wore boots.

Clamming with bare feet was the norm, as was using a screwdriver to free mussels from the thick portions hanging onto the edges of the shore. Not one word was thought about dangers or pollution, and we ate everything eagerly. It was a naive and a fairly environmentally safe time. Not anymore.

Now we are faced with a new danger that we bring into the outdoors. We crave as a clean environment. Obviously researchers have now shown this to be a myth, and we are in the middle of a desperate time to try to save our health and that of Mother Earth.

The trail winds through pines; the canopy hushes in a small breeze. You breathe deeper, certain that fresh air will rinse the city from your lungs. After all, haven’t we been told that forest therapy is one of the best things for us? Aren’t we being encouraged to get outdoors more and to exercise there? When you exercise, what are you doing? Yes, you’re breathing deeply.

But the air that enters carries invisible companions: plastic microfibers — shed from jackets, socks, packs, and shoe soles — that ride as dust, cling to dew, and drift across ridgelines. We once pictured microplastics as an ocean problem. New evidence says they are also a trail problem — and, by extension, a human one. In high-use backcountry, hikers themselves are now a source of the very pollution we try to escape.

The invisible payload we wear (and leave behind)

In 2025, the UK’s National Oceanography Centre reported that roughly 70–71% of ocean microplastics are microfibres — the kind released from clothing, textiles, and fishing gear. If we wear synthetics, we help supply that stream.

Every stride, seam rub, zipper tug, and sock friction frees fibers; rain and runoff carry them from trails into streams and lakes, and wind returns them to us through the air. It is a frightening cycle of which we are a major part and of which we mostly remain ignorant.

Researchers and land managers have begun to quantify this “recreation shedding.” Early field work and event-based studies suggest synthetic apparel and soft-soled footwear can be significant microplastic sources in remote areas, with measurable spikes where foot traffic is heavy. In short: the cleaner and more popular a trail looks, the more likely it is experiencing a steady drizzle of microscopic fibers — some of which we re-inhale.

It’s not just what we wear on a hiking trip. Washing gear before or after a trip releases vast numbers of fibers into wastewater; many treatment plants aren’t designed to trap them. Those fibers eventually reappear in rivers, soils, and air, completing a cycle that leads back to our mouths and lungs. Even protected landscapes are not spared: atmospheric studies show microplastics raining onto remote parks and wilderness, carried aloft and dropped far from their sources.

What plastic specks do in bodies and minds

Finding microplastics around us is one thing; finding them inside us is another. Evidence now shows microplastics in human blood, lungs, placenta, testes — and even in brain tissue, including the olfactory bulb (our smell center), a route that may bypass normal protective barriers.

Lab and autopsy studies are cautious but sobering: particles can lodge in tissues, irritate cells, and carry attached chemicals — plasticizers, PFAS, and persistent pollutants — into places they don’t belong. How much of this causes inflammation? We know that inflammation is now one of the major factors in mental disorders. Could recreational products and clothing can be one of the main drivers of mental health issues?

Environmental and medical journals converge on several plausible pathways: inflammation and oxidative stress; respiratory irritation that may worsen asthma or COPD; and gut-barrier and microbiome changes. Early neuro-pathway findings — particles in brain tissue — raise concern about subtle cognitive or mood effects.

Quantification is evolving, but exposure is undeniable. Depending on our behavior and environment, we may inhale or ingest tens of thousands of particles annually — more if we rely on microplastic-shedding products or spend time in polluted outdoor air. The World Health Organization cautions that evidence remains incomplete, but the ubiquity of exposure and biological plausibility demand urgent attention.

How many times do these groups have to sound the alarm before we listen to it? None of this means we should stop going outside. It means we should go outside differently.

Walking wiser: reducing what we shed and what we breathe

The paradox is plain: hiking supports mental health and resilience, yet our gear can undermine the “clean air” we seek. The solution isn’t retreat; it’s redesign and habit change — at the individual, industrial, and policy levels.

1. Choose and use lower-shed gear. Favor natural or blended fibers (merino, heavier canvas layers) in base and mid-layers; keep delicate synthetics under abrasion-resistant shells; and pick harder-soled footwear when feasible. For synthetic pieces you love, wash them less often and use microfiber-capture tools (machine filters, washing bags), cold water, and gentle cycles. Are those detergent pods or sheets good for the environment, or is liquid better?

2. Rethink trail density and maintenance. Popular routes concentrate shedding. Land managers experimenting with seasonal rest days, reroutes, and boot-brush stations can reduce local fiber buildup. Citizen science — simple microfiber sampling kits — can also help prioritize hotspots.
Back policy that tackles the pipeline.

3. Support municipal upgrades to wastewater filtration, extended producer responsibility for textiles, and tire standards that reduce micro-rubber. Do you realize how much rubber is shed from all of the automobiles that are on our highways, and how that shed material works its way into the air we breathe?

4. Encourage manufacturers to develop low-shed knits and disclose shed-rates so consumers can compare products. Too often, we took the easy way out and chose cheaper fibers made from oil that are ending up damaging our health.

5. Can you begin to make an important contribution? In the meantime, protect your own lungs and gut: avoid heating food in plastic, use glass or metal bottles, keep air filters clean, and air-dry synthetics away from living spaces. On the trail, pack out all plastics — including frayed rope ends or shredded packaging.

We go to the woods to heal ourselves. That purpose still remains. But it now comes with a clearer view: we have turned clothing into dust, and dust into a supply chain that ends in our lungs. The solution isn’t to fear the trail — it’s to change what we bring to it and what we ask of those who make our gear.

Do the manufacturers of outdoor clothing have a commitment to exclude these dangerous materials from their manufacturing process? Every piece of rainwear, every boot, every backpack, everything we bring with us, brings destruction, but profit has sway over what is made and what is sold.

If we want the forest’s air to heal us, our footsteps must stop seeding it with what hurts.