Is that fog or smog over Utah’s Wasatch Front? During an inversion, it might be both

In the thick of Wasatch Front air quality problems last week, many residents looked out their windows and asked: Is it really so polluted I can’t see across the street? Or is that just fog?The answer is complicated. Fog is mostly what obscures visibility. But pollution is at least partly what is causing the fog.After an inversion settled into the valley early last week, visibility plunged, and Salt Lake County exceeded federal standards for small particulate pollution on several consecutiv