That's the way I took it as well. And it is true in some places. When I first moved to the Los Angeles area long ago it was quite smoggy. But look at it now htt

That's the way I took it as well. And it is true in some places. When I first moved to the Los Angeles area long ago it was quite smoggy. But look at it now http://aqicn.org/city/los-angeles/ http://aqicn.org/city/los-angeles/ (all green = aqi reading less than 50).