Why air pollution is better, but not for everyone
We've had a Clean Air Act since the end of 1970, and generally cleaner air since that time.
But there is still pollution out there, and you are more likely to be exposed to it if your skin is darker.
Researchers at the University of Washington looked into the numbers, and found that non-white people are more likely to be exposed to the full list of six major air pollutants than white people.
Julian Marshall and Jiawen Liu led the research and share highlights with us.