Propane is a clean burning, non-toxic source of fuel. Research shows that properly maintained propane-powered forklifts produce significantly less emissions in the way of carbon monoxide, nitrogen oxide, hydrocarbon, and particulate matter than comparable gasoline- or diesel-powered forklifts.

This secondary source of pollution is eliminated because propane-powered forklifts carry their fuel in a pressure-tight, sealed system that avoids any spillage or evaporation into the atmosphere.

A research study conducted on which forklift fuel option had the lowest emission impact found propane to deliver the highest total energy efficiency. Propane received an efficiency rating of nearly 90%, followed by diesel at 85% and gasoline at 82%.

Reference Links:  

http://www.npga.org

http://www.ForkliftPropane.com