All I know, John, is that it is converted- I don't know if that means purified. I do know that the EPA approved it.

As far as Alaska's pollution ranking is concerned, I have read several approaches to that. One says that all the flying Alaskans have to do (few roads, waterbound towns)accounts for it. A different one postulates that the mining and oil industries are mainly responsible for it. That one makes more sense to me.

By the way, I read the other day that Alberta, Canada, is going to or is in the process of mining oil shale and that that is or will be responsible for an appalling amount of air particulates.