You’ve likely never heard of Esquel Group, but chances are that you’ve worn or purchased one of its shirts. The private textile manufacturing firm is the world’s No. 1 exporter of men’s cotton shirts, producing shirts for brands like Nike and Ralph Lauren.

Esquel Group has earned praise over the years for being a world-leader in sustainability. The company reduced its own energy consumption by 43% from 2005 to 2014, and its water consumption by 57% in that time. Speaking at Fortune’s Brainstorm E conference in Aspen on Tuesday, Esquel chairman Marjorie Yang said those accomplishments took buy-in from the entire company.

The importance of eco-friendly business practices crystallized for Yang in the early 1970s, when she was in her 20s and before Esquel Group had been formally founded (in 1978, by her father). She was visiting one of her father’s dyeing factories and heard, from an employee there, that the fish in a pond nearby had all died. When Yang asked why, she recalls, the person said, “Hello, we are in the textile business. She continued: “So I went home and asked my father [if such practices were obligatory] and he said, ‘That is not necessarily so.’ That is: the prevailing attitude among many in the industry was, as Yang puts it: “Wherever the fashion business goes, rivers have to turn into different colors. But it does not have to be that way.

The experience, “was the start of our journey, Yang says, “to use knowledge to offset this myth that if you’re in the textile business you have to be polluting.

But turning Esquel into a leader in sustainability couldn’t just be done at the senior level. Yang, who became the company’s CEO in 1995 and has now transitioned to being its chairman, decided she needed, “to convince the people in the company that this is important to them, and let them find a way to do it. I feel very strongly that if you’re really going to do this, you have to adopt it as a way of life, for everyone. We can say we’re going to do something top-down, but then if everyone goes home and leaves the faucets on in the dormitory, or has air-conditioned rooms with broken windows or open doors, it defeats the purpose. So to do this, you have to let people feel that they want to do it.

Part of encouraging people to want to do it? Remind them, Yang wisely points out, that if an industrial company is polluting, “the people working there are the first to breathe it in.