Effectiveness of idle reduction technologies in reducing driver exposure to diesel emissions

The purpose of this study was to investigate the effectiveness of idle reduction technologies (IRTs) in reducing driver exposure to diesel exhaust, and to study the cost effectiveness of these technologies. IRTs are devices that provide heating and cooling to the cabin of a truck without idling the truck engine. The focus was on diesel-powered IRTs (auxiliary power units and fuel-operated heaters), and their impact on particulate matter (PM2.5) exposure of drivers sleeping or resting in the truck’s cabin. The focus was on diesel-powered IRTs as these devices generate their own emissions, potentially exacerbating in-cab exposure levels. The project involved initial field data collection at truck stops in the states of Georgia, Texas and California. This was followed by laboratory testing in an environmentally controlled test chamber on a sample of trucks, with and without the use of IRTs. The study findings showed that the use of IRTs resulted in a significant reduction of PM2.5 levels in the truck cabin when compared with the baseline scenario of a truck parked with the engine off and the doors and windows closed. Idling the truck engine and running the air conditioning system was also found to reduce in-cabin PM2.5 levels relative to the baseline. The study supports the premise that IRTs reduce driver exposure to diesel exhaust. Additionally, it was found that these devices are cost effective in that they all have payback periods of less than five years, making them viable alternatives to idling the truck engine during long-duration rest periods.