Sorry to disagree old boy......the ban of lead...or the reduction of same, was an enviromentle concideration. Here goes and I'm not tyring to start a flame war! But.....

THE BIG CON
Eventually the blankets of sulphur and nitrogen oxides, better known as smog, grew so thick and so unbearable that "public opinion" caused America's legislators to start looking for answers. Obviously the place to start was with the oil companies. The oil companies announced quite loudly, and mostly erroneously, that the problem was "so many cars". There were only two solutions, they said: either limit the number of cars, or put something into the cars to "change" and limit the emissions. Was such a thing possible, asked the legislators? Certainly, replied the oil companies. Let us tell you about "catalytic converters" which can be fitted to the exhaust system of every car. The legislators, although they toyed with the concept, were not about to try and seriously interfere with people's rights to drive motor cars. Such action was perceived as electoral suicide, especially when there was the alternative "magic bullet" solution of converters available. Neither were they about to listen to all the "extremists" who were trying to tell them that the problem was in the type of oil being refined in the first place, and the only long-term solution was to get the oil companies to clean up their act. Such people contribute very little to election campaigns; the petrol chemical giants contribute millions.
There was only one problem left for the oil companies. Unfortunately, while platinum doesn't react to any great degree with the products of burnt petrol, it reacts very readily with lead-so readily, in fact, that burning a single tankful of "leaded" petrol in a car with a catalytic converter will render the converter useless. (This is the reason it is illegal to put "leaded" petrol in the fuel tank of a car designed to run on the "unleaded" variety.)
Trouble was, the oil companies couldn't simply stop putting lead in petrol, because the original reason for its presence-to stop "pinging"-still existed. There were available alternative additives that could be used, but these all had the disadvantage that, untreated, they produced emissions far more deadly than even the lead. On the plus side, however, these emissions could be filtered out by catalytic converters. What was needed, then, was a campaign to convince people that "leaded" petrol was a grave danger to the environment, and that the only solution was to cease using it, replace it with the "unleaded" variety, and then run the emissions through a catalytic converter. Such a campaign would ensure that legislation was passed forcing the fitting of catalytic converters, which would overcome the original problem for the oil companies-the increased levels of sulphur and nitrates in their fuel. You see, the campaign never had anything to do with lead: it was simply a matter of convincing people to use a fuel that wouldn't wreck the converters, so that the petroleum companies didn't have to spend any more money refining the oil and could get away with selling a dirtier product, forcing the motorist to bear both the responsibility and the cost of trying to clean up the air.
Anybody who doubts it was the quality of the petrol rather than the number of cars which caused the massive increase in smog in the period in question, need only look to actual figures. While it is true that the number of cars in use was increasing, the rate of increase was fairly steady. At the height of the "smog wars", however, the levels of emissions were increasing at nearly four times the rate of growth of car ownership. On top of that, this was the period where petrol was starting to get more expensive, and "economical" engines were becoming the order of the day. That is, although both car ownership and petrol consumption were on the increase, rate of ownership far outstripped rate of increase of consumption. (Source: Peter Sawyer, Green Hoax Effect, Groupacumen Publishing, Wodonga, Victoria, Australia, 1990)