Techniques used in addition to standard precautions to decrease transmission of microorganisms less than 5 p in size or those attached to dust particles. Patients are placed in a private room, preferably one with negative air pressure and between 6 and 12 changes of air each hour. Hospital workers should wear respirator masks when in the room. If transport is necessary, the patient should wear a surgical mask. Patients with diseases such as active tuberculosis, SARS, varicella, and measles are placed on airborne precautions.