Temecula getting smoggy

I looked on the Best Places to Live site and was surprised at how low Temecula was ranked. The one thing that stood out was air quality. Now, I chose Temecula over Riverside because the air quality is quite a bit better there. I can visually see the difference most days and let's face it, Riverside has some of the worst air in the U.S. and that's not going to change anytime soon. The brown layer I see as I drive to work is not appealing at all. But maybe Temecula's air is getting worse. I have noticed more smog lately and I didn't see it before. More cars and people might make a difference, but there is usually a nice ocean breeze around 3 PM to cool things down and clear it out. What happened?