Final answer:
Hygroscopic condenser humidifiers increase efficiency using hygroscopic crystals, which attract and hold water molecules, maintaining desired humidity levels.
Step-by-step explanation:
Hygroscopic condenser humidifiers (HCHs) provide higher efficiency through the use of hygroscopic crystals. These HCHs leverage the property of hygroscopic materials which have the ability to attract and retain water molecules from the surrounding environment through physical absorption or chemical reaction. By using hygroscopic crystals the humidity levels can be efficiently controlled and maintained which is essential in medical settings such as respiratory therapy where the moisture content of the air provided to patients is critical.