Cold Start/Idling Emissions

Principal Investigator: Randy Martin (USU), Joe Thomas (WSU)

Reducing automobile emissions has been a central component of the state’s plans to improve air quality. Unfortunately, there is little literature or data that identify the benefits or consequences from changes to the way individuals and fleets start their vehicles, particularly under Utah-specific conditions. A small, earlier study measured the pollutant and pollutant precursor emissions of three vehicles to compare cold and hot start conditions with different idling times. This modest study found that hot starts provided a significant decrease in emissions compared to cold starts and that there were generally less pollutant emissions from a ten-minute hot start than from ten minutes of idling. These results demonstrate the importance of further study to examine the effects of vehicle starts on emission levels under Utah-specific conditions and over a broader range of vehicle types.

Relevant Documentation