Building anything in California near transit stops is hard enough, but many affordable housing advocates argue that we should only build subsidized homes for low-income residents — and not market-rate homes for higher-income people. They cite evidence that low-income people are much more likely to actually ride the transit where they’ll live, as opposed to high-income people who will still drive.

It’s true that we should build as much affordable housing (and offices) near transit as we can to boost ridership. But we should also allow market-rate development near transit, too, for similar environmental reasons.

Yes, high-income people near transit probably won’t actually use the transit that much. But they will on balance drive significantly fewer miles than if they lived in sprawl areas. And fewer driving miles means less pollution and fewer greenhouse gas emissions.

Ironically, the evidence for this environmental benefit comes from a study meant to document how important it is for low-income residents to live near transit. The nonprofits TransForm and California Housing Partnership Corporation released a study [PDF] in May 2014, based on Caltrans’ California Household Travel Survey (CHTS), arguing explicitly for affordable housing near transit. In fact, they used the data to argue against locating higher-income housing near transit, pointing out that higher-income households drive more than twice as many miles and own more than twice as many vehicles as low-income households living within 1/4 mile of frequent transit.

But the data actually revealed something more important: higher-income residents near transit drove almost 30 miles fewer per day than similarly situated people in sprawl areas. By comparison, low-income residents only drove about 20 miles fewer per day, compared to similar income sprawl residents. Check out this chart that summarizes those results:

So while I agree we want to locate low-income residents near transit, we also need high-income people living in cities near transit. Otherwise, the increased driving miles will mean more traffic, pollution and unattainable climate goals.