Which gas is most associated with aerosol cans and refrigeration?

• A. Methane
• B. Chlorofluorocarbons (CFCs)
• C. Nitrous oxide
• D. Ozone

Answer: (B)

Chlorofluorocarbons (CFCs) are the gas most associated with aerosol cans and refrigeration. Their widespread use came from their stability, low toxicity, non-flammability, and the ability to be stored as liquids under pressure—properties that made them excellent as spray propellants and as refrigerants in cooling systems. However, when CFCs reach the upper atmosphere and are hit by UV light, they release chlorine radicals that catalytically destroy ozone, weakening the protective ozone layer. This harmful impact led to international action to phase out CFCs under the Montreal Protocol and to replace them with alternatives like other refrigerants and propellants. The other gases listed—methane, nitrous oxide, and ozone—are significant atmospheric gases with their own roles in climate and chemistry, but none are the gas traditionally used as an aerosol propellant or a refrigerant in the way CFCs were.