What is the purpose of soda lime?

The purpose of soda lime is to remove moisture and toxic gases and prevent their retention. This makes it a critical component of medical, diving and mining equipment, where it filters out poisonous carbon dioxide from the breathing air. In industrial use, it acts a powerful drying agent.

Soda lime, an alkali, is a caustic mixture of mostly calcium hydroxide with sodium hydroxide and potassium hydroxide appearing as grayish-white granules. It works by either absorbing the carbon dioxide or converting it into solid calcium carbonate. While beneficial, soda lime is highly corrosive and needs careful handling to prevent accidental ingestion.