The Centers for Disease Control & Prevention require a minimum amount of air changes per hour (ACH) for different medical environments that use air cleaning devices.

To ensure your HEPA filter appliance is providing an adequate and safe level of air filtration, the CDC has provided the ACH guidelines below based on what type of room or environment in which you wish to operate. This information is known to be current as of 2024, however the information below is meant to provide a generalized overview. It is the user’s responsibility to review the most current guidelines here. The following list of requirements applies to ALL applications:

• The air change information below is contingent upon a HEPA filtration efficiency of 99.97% or higher with a 0.3 micron particle size. All Wind Wizard™ filters with the HEPA designation will automatically meet this efficiency rating.

• Differential pressure between the containment room and neighboring space(s) should be a minimum of 0.01” water gauge (2.5 Pa). For the highest level of safety, an alarm should be installed to indicate if this differential is ever compromised. The requirement of an alarm varies depending on the application.

Diagnostic & Treatment Rooms

For a basic examination room where patients are seen for treatment and basic medical care, the CDC recommends a minimum of 6 ACH. There is no requirement to exahust the air directy outdoors and a negative or positve pressure environment may be used.

Operating & Critical Care Rooms

For an operating room, labor and delivery room, or any other procedure room, the CDC recommends a positive pressure environment with a minimum of 15 ACH. There is no requirement to exahust the air directy outdoors.

Isolation Rooms

Used to control airborne infection, an isolation room is employed to house patients infected with viruses such as SARS and Covid-19, among others. In recent years this is the most common use of HEPA filtering systems. For this appliction, the CDC recommends a negative pressure environment with a minimum of 12 ACH.

Sterilizing & Supply Rooms

Often referred to as ETO Sterilizer Rooms or Sterilizer Equipment Rooms, the CDC recommends a minimum of 10 ACH. For this application, it is a requirement that the air be exhausted directly to the outdoors and a negative pressure environment be maintained.

Service Rooms

Service rooms may be any of the following: Food Prep Centers, Ware Washing Rooms, Laundry Rooms, Trash Chute Rooms, Bedpan and Bathrooms, or a Janitor’s Closet. For these spaces, the CDC recommends a minimum of 10 ACH. With exception to Food Prep Centers, it is a requirement that the air be exhausted directly to the outdoors and a negative pressure environment be maintained.