California’s air pollution control standards have drastically dropped the amount of diesel particulate matter in the air, and cardiopulmonary deaths attributable to air quality.

Scientists at UC Berkeley are hailing the state’s diesel engine standards and other measures imposed over a number of years, even in the face of loosened environmental regulations in recent years.

If one has never seen the pictures of the city of Los Angeles before the Clean Air Act, they look like something out of the movie Escape from L.A. But encouraging shifts away from high-sulfur fuels, and replacements of diesel ships with electric ones, has gradually scaled the horror show back—despite the fact that still today there are more cars registered in the state of California than any other state.