Buses head out at the Denver Public Schools Hilltop Terminal Nov. 10, 2017. Andy Cross / The Denver Post via Getty Images
By Corey Binns
Before her two kids returned to school at the end of last summer, Lorena Osorio stood before the Westminster, Colorado, school board and gave heartfelt testimony about raising her asthmatic son, now a student at the local high school. "My son was only three years old when he first suffered from asthma," she said. Like most kids, he rode a diesel school bus. Some afternoons he arrived home struggling to breathe.