Over the past five years, Lululemon’s Align leggings and shirts have become a $1 billion business, bolstering the company’s projected $9.6 billion in global revenues. Demand for the shirts means the company is now making millions of these garments a year.

The key ingredient of the Align garments is nylon, which is blended with lycra for stretch. Since both of these are plastic-based materials, they’ll end up sitting in landfills for centuries, where they won’t biodegrade but instead, break into tiny fragments called microplastics that will end up in our oceans and food systems.

Lululemon has a plan to reduce the environmental impact of these clothes. It’s unveiling a new material: the world’s first nylon that has been recycled with enzymes back into nylon. To demonstrate the tech, the company has used it to make prototypes of its best-selling Swiftly Tech long-sleeve shirt. But Lululemon’s broader goal is to build a circular system where nylon in garments can be recycled back into nylon, significantly decreasing the company’s environmental footprint.

Fabric-to-fabric recycling is not new. Companies like Circ have developed a system to break down garments made from polyester and cotton, then recycle the materials back into new fabrics. Lululemon, however, tends to use a lot of nylon in its garments, which is more expensive than polyester but is also more durable and has more performance benefits. The company wants to create a system that would allow it to recycle nylon without diminishing its quality.

To do this, Lululemon has partnered with Australian tech company Samsara Eco which uses enzymes—proteins that act as catalysts in chemical reactions—to break down plastic polymers, transforming them into their original chemical-building blocks, called monomers. Then, it can transform these monomers back into polymers that are chemically identical to brand-new materials.

Until now, Samsara Eco has used this technology to create polyester, but this partnership with Lululemon marks the first time it is working with nylon. The products made in the initial run perform identically to shirts made with virgin nylon, says the company. “Our Swiftly top samples provide the same fit, feel, and quality [customers] expect from Lululemon products, which was absolutely critical to us,” says Yogendra Dandapure, VP of raw materials innovation at Lululemon.

Now, the companies are working together to scale this technology up so that Lululemon can move toward a circular system, which it laid out in its 2020 impact agenda. One of its top priorities was developing sustainable materials, since fabrics account for around half of the company’s carbon impacts. It has plans to transition all of its materials to more sustainable alternatives by 2030, but when it comes to nylon in particular, it promises to fully transition to recycled or renewable content.

This month, the environmental advocacy organization Stand.earth argued that Lululemon is misleading customers about its environmental impact, particularly in its reliance on fossil fuels for its plastic-based materials and using factories in Asia that burn coal. It filed a complaint to the Competition Bureau of Canada, saying “[Lululemon] benefits from a carefully constructed image of environmental sustainability and wellness, and claim to make products that contribute to a healthy environment, but their exponential growth has been built on fossil fuels, from clothing literally made from fracked gas.”

In response, Lululemon issued a statement saying that it is on a path to achieving a carbon footprint of zero by 2050, from using renewable energy in its owned and operated facilities and working with its partner factories to help reduce their carbon emissions.

When it comes to materials, transitioning to recycled materials would result in a significant reduction in the carbon emissions in the manufacturing process. And it also means no longer having to rely on fossil fuels to manufacture plastic-based materials. “[We] have the ability to create new recycled nylon and polyester made from apparel waste, bringing us a step closer to our end-to-end vision of circularity,” says Dandapure.

In my recent conversation with Calvin McDonald, Lululemon’s CEO, he said the company has plans to continue its fast rate of growth, particularly as it expands globally. It’s ability to meet its environmental targets depends on how quickly and effectively it can scale it’s sustainability efforts, including material innovations like this enzymatically recycled nylon. The question is how soon Lululemon will be able to collect leggings and tops from consumers, and transform them back into new products. We’ll have to wait and see, but consumers and environmental organizations will be paying close attention.