It’s not hard to understand why many parents don’t let their kids walk and bike to school in Los Angeles where streets are designed for the fast movement of cars. In LA, crashes are the leading cause of death for kids aged 4 to 15. To keep kids safe, parents revert to cars—even if the trip is a short one.

It is short trips like the journey to school that is one reason why transportation emissions keep going up in America—a third of vehicular trips are three miles or less. Yet you can see the evidence that people want to walk and bike on virtually any weekend in the U.S.

People of all ages move through our cities during open streets events—in LA’s case, it’s over 100,000 people per event. But the reason those people aren’t traveling on foot or bike along the same streets to school or work on Monday? They don’t feel safe. By making streets safer, we not only improve the lives of urban residents but also help save the environment.

In Norway’s capital of Oslo, the city replaced nearly all on-street parking with bike lanes and sidewalks in an effort to make most of its downtown car-free. Speed limits were dramatically reduced, with “heart zones” drawn around the city’s schools where officials made physical changes to streets to protect students walking and biking to school, including closing streets to cars during school hours. The result? Not a single pedestrian or cyclist death was recorded last year.

Meanwhile, Oslo benefitted from cleaner air and reduced emissions, showing us that the same tools that make our streets safer also make them cleaner. At a time where we need to slash emissions fast, it seems safer streets are one of the best tools we have.