Knowing the chemical process that forms ground level ozone is the first step in coming up with solutions. Fumitake Chisaka of the Mechanical Engineering Laboratory, Namiki 1-2, Gakuen, Ibaraki, in Japan in his article “Effect of Vehicle Exhausts Control for Photochemical Smog Prevention," showed the need for a system that reduces the number of hydrocarbons that enter the atmosphere as well as a second system that will handle the NO emissions.
The use of catalytic converters in automobiles was a step in the right direction. These additions to the exhaust system use either platinum, rhodium or a combination of both to cause a chemical reaction with unburnt hydrocarbons to produce carbon dioxide and water instead of Nitric Oxide. These devices only work in unleaded fuel vehicles though as the leads in regular gasoline prevent the reaction from occurring.
As for the other major producers of the initial pollutants that form smog, the Federal Government has been revising the Clean Air Act of 1970 on a continual basis to help remove these toxins from the air. A major overhaul in 1990 targeted these gases in particular.
The best possible solution to this problem is finding a source of energy that doesn’t involve burning hydrocarbons. Solar, Hydro and wind energy are all good starts (even “clean" coal isn’t bad) but they aren’t yet at a level where they can be used as the primary means of locomotion for a practical passenger vehicle. When these technologies have advanced enough then maybe we will have total relief from the effects of photochemical smog.