Motor vehicle emissions under reduced ambient temperature idle operating conditions

Abstract During winter months, motor vehicles are typically operated with extended preliminary idle periods. Total hydrocarbon, carbon monoxide, nitrogen oxides and formaldehyde emissions are examined under idle operation at 20,40 and 68°F with six gasoline fueled vehicles (including non-catalyst, early catalyst and late model catalyst) and a methanol-fueled prototype vehicle. The emissions were substantially reduced by the late model catalyst control technologies at all temperatures examined. Formaldehyde emissions were elevated with methanol fuel.