This makes me think of A Snow Mobile for George [1]. I'm not sure what the lead pollution impact of 2 stroke engines are (probably awful if you were able to find/use leaded gas) but in terms of low-hanging fruit its a perfect example of how regulation or deregulation can have a large effect on pollution.
Growing up using 2 stroke weedeaters and chainsaws I had no idea how polluting they are. Granted we were using terribly small amounts of gas compared to snowmobiles but it still made me think of the health dangers of the exhaust. I have some nostalgic feelings towards the smell of 2 stroke exhaust (diesel exhaust as well) but after seeing the documentary I wouldn't buy another 2 stroke anything.