It is more useful to express the OPE as a function of [NOx] rather than as a function of [NO2] because of the rapid cycling between NO and NO2. Derive an expression for the [NO2]/[NOx] ratio as a function of [O3] only. Replace into your OPE equation. What do you conclude as to the dependence of OPE on the ozone concentration? Explain qualitatively your result. Does this dependence hinder or enhance the effectiveness of NOx emission controls for reducing ozone levels?