Practices are raising questions about the airborne transmission of the COVID-19 virus and how they can best prepare for a higher number of community cases in the future.
The importance of good ventilation in health care, and other settings where people gather, is one of the learnings from the current pandemic.
I know the RNZCGP is looking at this in it's review of Foundation Standards as a result of the pandemic. The approach they will take will need to marry the difficulty of adjusting the current buildings we work in, with what the best evidence tells us provides the safest environment.
Not an easy task.
For a "new build" or for a group setting up a new health service in the future, I am sure the quality of ventilation will be one of the concerns about the physical space they work in. New builds will need architects to be aware of air flow, this may add cost but at least can be done at the design stage, retro-fitting good ventilation into current buildings is going to be a greater challenge.
Many of our general practices are in converted villas, which have been altered with a focus on privacy and security rather than ventilation. Windows have been permanently locked, doors soundproofed, draughts excluded.
Even many of our newer buildings have been designed for efficient patient flow, not for efficient airflow.
I’ve been into multiple clinic "isolation rooms" that have been crafted from the small room closest to the back door, used pre-COVID-19 for storage, because the lack of windows and natural light put people off working in them.
A lot of practices have hired cabins for “red zone” swabbing which are technically “outside” but become tiny hot closed boxes when the sliding door and windows are closed in the interests of privacy.
It is my expectation, and that of many primary care clinical leaders, that clear and science-based advice will come from infection control specialists in consultation with the RNZCGP and others in the near future on the appropriate next steps we need to take around ventilation.
In the interim the following resources may be useful. And please feel free to share any resources you may have with me.
The first thing we need to emphasise is that PPE, staff vaccination and source control through streaming, mask use, vaccination of patients and the usual hygiene measures are the most important things a health care facility can focus on and provide the majority of risk reduction.
This International Journal of Thermofluids review article describes the complexity of how airflow impacts on viral transmission and how what we might think superficially is “good ventilation” may not be. My main take home message from this was that retrofitting solutions is very complicated and requires highly specialised engineering input.
This Environment International article 'How can airborne transmission of COVID-19 indoors be minimised?' is a good review of the evidence.
And these recommendation from the USA CDC discussing ventilation in buildings.
Although hospital-based, this study demonstrates the value that air filtration and UV sterilisation units can have on reducing detectable SARS-COV2 in the air of a hospital ward. It does not demonstrate any actual clinical outcomes of this reduction, and with all this evidence we should be wary of proxy markers of impact. The question we don’t yet have an answer to is whether air filters reduce the risk of healthcare facility associated transmission of SARS-Cov2.
The WHO guide to ventilation is the most authoritative I am aware of. This roadmap aims to define the key questions users should consider to assess indoor ventilation and the major steps needed to reach recommended ventilation levels or simply improve indoor air quality (IAQ) in order to reduce the risk of spread of COVID-19.
And a nice brief WHO advice page on ventilation.
They refer people onto the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) as an authoritative group providing guidance in the US context on in room air filtration. And here is some general ASHRAE advice for commercial buildings which many will find useful.
It is hard to provide specific guidance for general practices as they are all very different in layout, and even within the building different rooms will have different considerations. Using air conditioning units on a setting that recirculates internal air is not advisable, having them properly serviced and filters changed and cleaned regularly is important.
Think about airflow in each room and if possible have an “entry” and an exit to the outside in mind so that the air in each room is being replaced with fresh air several times an hour.
Air filtrations systems may or may not add additional protection from airborne infection to staff inside a general practice service room, the evidence that they add value is based on very high risk areas in hospital settings, and relies on proxy markers like the concentration of detectable virus particles in the air.
Portable HEPA filter air purifiers cost in the region of $500, and based on the current evidence clinics may want to consider using them, particularly in poorly ventilated spaces where potential COVID-19 patients might be treated.
Mainstream retail stores can provide true HEPA filters.
Air filters are at best only an adjunct to preventing transmission and an additional action that might help where good ventilation isn’t possible.
Remember the “swiss cheese” model of preventing transmission which requires the consistent application of multiple actions – vaccination, streaming, spacing and specific PPE are vital.