Which of the following types of humidifiers are used in clinical practice? 1. Heat and moisture exchanger 2. Passover humidifier 3. Bubble humidifier

a. 1 and 2 only
b. 2 and 3 only
c. 1 and 3 only
d. 1, 2, and 3

ANS: D
Active humidifiers typically include (1) bubble humidifiers, (2) passover humidifiers, (3) nebuliz-ers of bland aerosols, and (4) vaporizers. Passive humidifiers refer to typical heat and moisture exchangers (HMEs).