Most of the smog
we experience here in southern
California is Ozone(O3):
This
type of smog occurs during the
warm months of the year, and most
common in the valleys...where
inversion layers are at their
greatest.
The
valleys of the Inland Empire are
the most prone to these
conditions.
Like to know what the air
quality is currently in your area?
Here are some links to air quality
readings across southern California and
the central coast region.