Does polyurethane turn into microplastics?

Yes, polyurethane does eventually turn into microplastics as it degrades over time, like most synthetic polymers. Polyurethane is a type of plastic, and while it is durable, it is not biodegradable in the short term. Over years to decades, exposure to sunlight, UV radiation, heat, oxidation, abrasion, and microbial action causes polyurethane to break down into smaller and smaller fragments. For example, polyurethane coatings on floors slowly wear into fine dust through foot traffic, faux leather made from polyurethane flakes and peels into small particles, and polyurethane foam breaks down into crumbs and dust. These tiny particles less than 5 millimeters in size are classified as microplastics and can enter soil, water, and air. Studies have found polyurethane microplastics in indoor dust from furniture and mattresses, in wastewater, and in the environment. However, polyurethane is more durable than some plastics like polyethylene, so it breaks down more slowly than single-use plastics. Water-based polyurethane and thermoset polyurethanes are more resistant to breakdown than thermoplastic polyurethane. While it does not dissolve quickly, over its lifecycle, polyurethane contributes to microplastic pollution, which is an environmental concern that has led to research into bio-based and biodegradable polyurethanes.