I recently read a piece about bootleg refrigerants containing methane and can be a safety hazard as far as explosion.
This of course is a result of increased costs of refrigerants due to the elimination of CFC’s.
Methane would be considered a contaminant in refrigerant CFC’s.
HCFC were to replace CFC’s but the biggest factors along with CFC’s was Methyl Chlorinated solvents used in Dry Cleaning and Chlorinated solvents used in bleaching paper.
Depending upon the amount of methane used, it could become explosive. Iso-Butane is now the common propellant used in pressurized cans.