“A study released last month by West Virginia University concluded that air pollution emissions from propane school buses are significantly lower than those from diesel buses. The differences are particularly large because school buses stop and go so often. For such stop-and-go routes, emissions of nitrogen oxides (NOx) were 34 times lower for propane than for diesel buses. On city and highway roads, these air pollution emissions were 15 to 19 times lower.” — read the full story at forbes.com