COVID-19 Practice Update: Air Treatment Office Policy
The following is based on a transcript of Michael Conner, PsyD speaking to a small group of business professional who were interested in knowing how to think about office air treatment. This was not a specification but a conversation about considerations.
The chances that a well informed therapist or their patient will become infected with SARS-Cov2 during an in-person therapy session are based on having an office space which meets physical requirements and carefully followed policies and procedures related to:
Office and building safety
Source control and risk reduction
Sanitization
Air treatment
Routine initial & pre-session screening
Patient education and informed consent
COVID-19 Air Treatment Office Policy Considerations
When Developing an Office COVID-19 Air Treatment Policy, psychotherapists and counselors should consider the following as a point of reference. These consideration are not recommendations that apply to every office.
A mask in and of itself is not adequate. Mask filtration is a variable.
Good ventilation in an office is necessary. At a minimum it should maintain background CO2 levels within parameters. 200ft3/min of fresh air evacuation is usually adequate for 500ft2 office. The minimum air exchange need to be anywhere from 6 to 50 total air exchanges per hour depending on the shape, volume of the office and the air treatment method. A square office is optimal for air treatment. CDC considers stand alone filtration to be air exchange. ultraHEPA filters down to 0.003 microns. TrueHEPA is filter at about 0.3 microns.
The SARS-CoV-2 virus can die from wind sheer, desiccation or impaction. Air filtration machines are violent in all these ways. Not only is the virus trapped in the filter but any virus escaping the filter is damaged and almost certainly killed within minutes. Dust may may escape but then dust is not living to begin with. So the value of filtration devise is not just how many particles escape. Ironically, scientists who attempt to capture live virus in room using an air suction device often kill most of the virus in the process.
A stand alone air filtration unit is useful especially if you can’t ventilate adequately, as we might expect during extremely cold weather. In extremely cold weather the heating bill can double if you ventilate to adequate levels. The CDC considers standalone medical grade air filtration to be an adequate substitute for air-exchange if properly placed. More air filtration and ventilation means less risk of infection from aerosolized droplets. However, more filtration is probably not adequate in the room is less that 200ft2. Research has shown that high turbulence in small spaces can interfere with filtration. Airborne virus-carrying droplets dry within minutes once exhaled. The are called aerosolized nuclei. Humidly can extend the life of a virus but humid can cause the virus to clump together and be pulled into a filtration device quicker.
Central heating and cooling is problematic as it may share air with another office and there fore must have proper filtration. The air supply and air return must be considered in the air treatment plan.
Stand alone air filtration systems include HEPA, TrueHEPA and ultraHEPA types. Medical grade filtration is TrueHEPA or ultraHEPA. The clean air delivery rates (CADR) of a filtration unit varies in cubic feet per minute. A CADR of 180ft3/min is usually quiet in a TrueHEPA machine. At full speed, 320ft3/min machine is noticeably loud. Adding machines to run at a lower speed can be very quiet.
A stand alone filtration system with TrueHEPA providing a CADR of 300ft3 per minutes can theoretically clear the air in a 3000 ft3 room in about 10 minutes (or a 5000ft3 room in 16 minutes) provided their is no turbulance that would disrupt air flow to the devise. Placing one standalone device on one side of a room will not clear the air as quickly in the opposite corner of the room. Placing 4 devices, each on opposite walls of the room will help insure air is exchanged equally throughout the room. Using 4 machines with a CADR of 300ft3 per minute will filter 5000ft3 in 4 minutes. A slower CADR for a longer period is recommended. Air clearance is usually best if the air is well mixed and circulation patterns are well established.
Virus-carrying droplets that are exhaled by an infected person dry out in a few minutes if the humidity is about 35% and the temperature is 70F. The aerosolized droplets can float for several days if the air is turbulent and there is not ventilation or air exchange. Aerosols don’t live forever. About 50% of the viruses that are exhaled die each hour in warm low humidity room.
The recommended distance between patient and therapist is 6ft minimum up to 10ft. An “airwall” between a patient and therapist is highly recommended as an added tool for office COVID-19 air treatment. An airwall redirects aerosols created by conversational speech. This is created by tower fan that creates a pressure zone and redirect air away from the therapist and patient.
Conversation volume should be limited to less than 40 decibels - shouting and singing creates “spray”.
Some time must be created between appointment to sanitize and fully ventilate the office to avoid accumulation of shared air. In a 500ft2 office the air should be cleared a least 6 times between appointments.
Simulated sunlight is highly effective. In one study 90% of the corona virus became inactive (dead) in 9 minutes in summer and fall conditions. Between 20 to 40 minutes of Ultraviolet-C (120V, 30w and 254 nanometers) in a proper dose is very effective but cannot be used with people or pets in the room. A timer is usually set that turns the system one and off. Under no circumstances should people expose their eyes to this radiation. The room must be fully ventilated after using UVC light to eliminate toxic gases. Some UVC treatment systems do not create toxic gases as a bi-product
Fogging an office with atomized “food safe” H2O2 (hydrogen peroxide) can sanitize both the office air and surfaces. This process requires 3 to 6 hours to sanitize the air and surfaces and time to allow the H2O2 to break down in H20 (water).
The reader is encouraged to take the training on this site in order to develop full appreciation of how to create a COVID-Safe office for psychotherapy. Readers are also encouraged to join the Oregon Therapy Forum to learn more about developing a COVID-Safe office air treatment policy at www.OregonTherapyForum.org. Members can find information, read discussions , post questions and share their experience with other members.