HEPA Filters


The campus response to the Coronavirus pandemic includes a combination of protective measures with vaccination and masking being the most important. 

The use of high-efficiency purified air (HEPA) cleaners has been suggested by agencies like the California Department of Public Health (CDPH) and the Centers for Disease Control (CDC) for improving ventilation indoors when there is insufficient fresh air introduction by HVAC systems, or natural ventilation from windows.

While the use of HEPA air cleaning devices may reduce the presence of airborne viral particles in a room, their use should be limited and carefully considered to reduce the creation of air currents that may pose problems


Facilities Services has increased the percentage of outdoor air in campus buildings where feasible, per CDC and CDPH guidance, as part of the multi-layer strategy to limit the spread of Coronavirus. There remain buildings without mechanical ventilation that rely on windows for fresh air that should be opened when spaces are occupied.  


The campus has generally assessed whether the use of portable or mounted High Efficiency Particulate Air (HEPA) filtration units, or other air cleaning systems, would reduce the risk of COVID-19 transmission and concluded that in most cases they should not be used because of the following: 

  • Air currents that can spread untreated air to other people in the space

  • Noise that increases with the fan speed

  • Maintenance and filter replacement considerations

  • Energy consumption and potential power failures

  • Theft of unattended devices

But, in some situations, a HEPA air cleaner may be acceptable.  Contact EH&S at 510-642-3073 or EHS@berkeley.edu(link sends e-mail) to determine the value of using HEPA air cleaners in your location.  Contact Facilities Services at 2-1032 to submit a work order to confirm that your area has sufficient electrical capacity for the HEPA filter.

  • Portable HEPA filtration units must be approved for use in California (look for the label CARB-compliant; this means they are tested for electrical safety and ozone emissions). 
  • Ensure the unit is sized appropriately for the intended space. Some large classrooms may require more than one unit. One method for selecting the appropriate size unit is checking that the Clean Air Delivery Rate (CADR) is at least 2/3 of the room's floor area (in square feet), with adjustments made for high ceilings. A list of units with CADR ratings can be found on AHAM's "Verifide" website.
  • For classroom use, look for quieter models with a noise level < 50 dBA if possible.

In all cases, it is recommended that each use of a HEPA air cleaner be thoughtfully reviewed before purchase.  Remember that ventilation is only one part of many strategies that limit the spread of Coronavirus.  Weigh the above considerations before contacting EH&S to determine whether a HEPA filter could be an option.  


Although fans can increase ventilation if installed where they bring in outside air, fan use is not recommended anywhere multiple people may be present in an indoor environment. A fan blowing across a sick person can increase risk of infection for others in a room.


The following websites offer more information on HEPA air cleaner devices and COVID-19: