Almost half of the word's population breathe air that is unsafe for humans. But, until now, it has been hard to tell where the most dangerous areas are.
TechRadar has reported that for the last year, Google has been driving its Street View Cars around Oakland, California, with air pollution sensors on the roofs – and now we see the first map of the results.
Check out the video to find out more about how this works, and what the results show.