That would probably be enough, but we have to be realistic. The first one would be to use cleaner cars of course, such as electric or hybrid cars. Another would be to use less greedy engines. The less fuel an engine consumes, the less it pollutes. Another possibility would be to equip all cars with catalytic converters.
Cars using leaded fuel are one of the biggest sources of air pollution in our cities.
That is a purely technological innovation. Other countries, like Sweden, have also banned leaded petrol by law. So it is simply no longer available there. Yes, there are. For example, the 1988 NOx Protocol to the Convention stipulates that unleaded petrol should be made available along main roads for cars equipped with catalytic converters.