Early refrigerators used toxic gases.

The groundbreaking invention of the refrigerator revolutionized food preservation, but its early incarnations were not without risks. During the 19th and early 20th centuries, toxic and flammable substances like ammonia, methyl chloride, and sulfur dioxide were used as refrigerants. Leaks from these systems could cause serious accidents, even fatalities. This danger drove the development of safer alternatives, leading to the creation of chlorofluorocarbons (CFCs) in the 1920s – which were later discovered to harm the ozone layer. This highlights the continuous evolution of inventions to improve safety and performance.