Refrigerant leak rates were measured for faulty air-conditioner evaporators removed from vehicles, and results indicated a range of very small to very large leaks. A survey of automotive air-conditioning service shops was conducted, and leakage scenarios were evaluated to determine possible worst case conditions for inhalation exposure to refrigerant for vehicle occupants. Refrigerant concentrations were measured in passenger compartments of vehicles. The maximum refrigerant concentrations measured for two vehicles were approximately 18,000 ppm (parts per million) and 16,000 ppm at a leak rate of 0.11 oz/min (3 g/min). Results from this work were utilized in a study to estimate the risk of exposure to refrigerants used in automotive air conditioning in the United States. 1998). The TNO studies confirmed the low toxicity of HFC- 134a. Results described in this publication were utilized in a comprehensive analysis of exposure to refrigerants used in motor vehicle air conditioning (Jetter et al. 2001). This information will aid the U.S. EPA Significant New Alternatives Policy (SNAP) Program in its assessment of other refrigerants for mobile air conditioning.

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