Not only air pollution - if I think about the two-stroke engines that typically power cheap two-wheel vehicles, noise pollution also comes to mind...
Even the smallest motorcycles are four-stroke, unless we're talking about hobbyist stuff like dirt bikes.
2 stroke engines on new vehicles were banned in India 20 years ago and there have also been some restrictions on re-registering old 2 stroke vehicles as well
you're not wrong they just solved that part of the problem already