China’s ride-sharing unicorn takes on a pollution crisis.

Didi Chuxing not only beat—but bought—Uber’s China business this summer, and not just because it benefits from a supportive home-team government. Didi, which generates 16 million rides a day, offered better services, and in this case, better service for Chinese users is better for the world.

Motor vehicle emissions are responsible for one-third of the dangerous smog in Chinese cities (much of which drifts outside China’s borders). Didi estimated that last year its car-pooling services helped reduce total car trips in the country by 1 million a day, which saved 500 million liters of gas, which cut 13.5 million tons of carbon emissions per day.

That’s not the only way in which Didi is a pollution-buster Didi’s taxi service reduces the time drives aimlessly cruise around across 400 cities; its bus service coordinates long-haul private buses for commuters; and car-pooling reduces congestion.