This engine is one of the worst in terms of pollution, as it directly passes oil to the cylinder for lubricating purposes and explodes at it with fuel. Four-stroke engines utilize a different method, avoiding this extra source of air contamination.
However, two-cycle engines are very commonly used in scooters, racing or dirt bikes, snowmobiles, karts, model airplanes, ...
There were some intentions of prohibiting its use, especially those inside cities, but it seems that finally they are allowed without limitations in multiple locations. They could be top contributors toward the toxic cloud, and for that some people are asking why create more pollution and health risks in exchange of engine performance for some people.
Users of this kind of engine usually defend it, without too many worries about environmental impact. Although it's true that the volume of four-cycle engines is greater and then they pollute much more than all possible two-cycle engines.
They are actually restrictions in a lot of states, while others use them even for government related activities like police, gardening, cleaning, ... What do you think? Is this an important step to fight against pollution?