Emissions of the refrigerants HFC-134a, HCFC-22, and CFC-12 from road traffic: results from a tunnel study (Gubrist Tunnel, Switzerland)

This study presents the quantification of the emissions of the refrigerants CFC-12 (CCl2F2), HCFC-22 (CHClF2), and HFC-134a (CF3CH2F) from road traffic in Switzerland. These gases are used as refrigerants in car air conditioning systems (A/C-systems) and in cool aggregates for refrigeration transport. All three substances act as greenhouse gases, and CFC-12 and HCFC-22 are in addition stratospheric ozone depleting chemicals. The measurements have been performed in a highway tunnel in the area of Zürich and cover a large number of individual vehicles, which are thought to be representative of a typical European car fleet. The average emission rates per vehicle were found to be 1.0 +/- 0.2 mg h(-1) for CFC-12, 0.6 +/- 0.4 mg h(-1) for HCFC-22, and 6.2 +/- 0.8 mg h(-1) for HFC-134a. These emission factors have been measured for driving vehicles and represent an average emission rate for all types of vehicles regardless of whether they are equipped with an A/C-unit or not. For an average vehicle equipped with an A/C-unit, these results translate into losses of about 14 mg h(-1) for HFC-134a and 20-30 mg h(-1) for CFC-12, when the estimated distribution of HFC-134a-A/C-units (45%) and CFC-12-A/C-units (3-5%) in the car fleet were taken into account. The emissions of CFC-12 and HFC-134a were mainly attributed to the losses from A/C-systems of passenger cars, whereas the emissions of HCFC-22 originate from losses of refrigeration systems of transport trucks. The observed emissions are discussed in respect to their environmental impact and compared to the overall greenhouse gas emissions of road traffic.