Figure 1-1
Atmospheric ozone (O3). Left-handed graphic: average O3 mixing ratio (in parts per billion by volume) as a function of altitude; center: photochemical processes responsible for producing O3 in the stratosphere and troposphere; right-handed inset: column abundance of O3 in atm-cm (i.e., the height of the O3 column if it were compressed to 1 atmosphere pressure). Although only VOCs and NOx are shown as ozone precursors, carbon monoxide (CO) can participate, in much the same way as VOCs, in the sequence of reactions leading to ozone formation. Source: Adapted from EPA 1998.
