Personally , I think it is ridiculous to care about the pollution caused by burning LPG for heat (or NG as I do ) when there are so many people still burning wood fires. Gets quite smoky here in SpringVale when there is no wind in the winter. Large volumes of smoke pour out of some houses in the hood. I note that Gas fire flues never need to be cleaned which shows you how little pollution they create compared to wood or coal fires.