Yareli Sanchez lives in Los Angeles and jogs regularly, but she never used to know if the day’s air quality was bad until after she had already set out for a run — her chest would tighten and it would become hard to breathe. She knew poor air quality triggered her asthma, but she didn’t have a convenient way to check the day’s pollution levels.For the past few months, instead of using trial-and-error, she’s checked UCLA’s new AirForU app, which uses GPS data to give her local air quality ratings. The app is useful for anyone in the U.S. who sees a hazy skyline and wonders how safe it is to breathe outside air.“I depend on the AirForU app now, and I use it every time I plan on running,” said Sanchez, who helped test it before its launch. “The app is really convenient for helping me manage my asthma and minimize my exposure to pollution.”