Since ozone reacts rapidly with nitric oxide (NO + O/sub 3/ yields NO/sub 2/ + O/sub 2/), no controls would be expected to be counter-productive in controlling ozone levels. This study of the photooxidation process lends support to this view with respect to metropolitan areas. In the process of examining the relationships, the following subjects are considered: Nature of the photooxidation process and calculation of no oxidation; reactivity coefficients of organics; calculations of ozone levels after no depletion; calculation of peak ozone levels; Los Angeles basin ozone levels; ozone levels at high hydrocarbons/NO/sub x/; emissions, ozone levels, and meteorology in metropolitan areas other than Los Angeles; the ambient air standard for NO/sub 2/ vs NO/sub 2/ levels; effects due to nitrates from NO/sub x/ emissions.