Over the last two years the nation had more polluted air days than just a few years earlier, federal data shows. While it remains unclear whether this is the beginning of a trend, health experts say it's troubling to see air quality progress stagnate.
There were 15% more days with unhealthy air in America both last year and the year before that there were on average from 2013 through 2016, the four years when America had its fewest number of those days since at least 1980.
President Donald Trump has repeatedly claimed just the opposite, saying earlier this month in Ireland: "We have the cleanest air in the world, in the United States, and it's gotten better since I'm president.