Air is used in hospitals for a variety of reasons. Firstly, it is important to maintain a clean and sterile environment in order to prevent the spread of infection. Air is used to circulate fresh air throughout the hospital, removing any airborne contaminants and providing a healthy environment for patients and staff. Additionally, air is used to regulate the temperature of the hospital, ensuring that it is comfortable for everyone. Finally, air is used to control humidity levels, which is important for patient comfort and to prevent the growth of mold and bacteria.