[I’m not an expert, but based on the degree of panic and activity and Corona Virus, I’m writing this in an attempt to be helpful.]
- The virus does not survive as an aerosol like measles, but it does appear to survive longer as a droplet than rhinovirus. I believe the reports of Dr. Ian Mackay (Flight of the Virus), that the virus does not survive outside of a droplet.
- Physicians who have treated this disease have died from exposure to the virus. (Dr. Marcello Natali in Italy, and Dr. Li Wenliang in China.)
- PPE shortages – facemasks, etc. – are putting physicians at risk.
- However, before addressing the PPE shortage, how can we reduce the risk of the ICU?
Airborne Droplet Dangers of the ICU with Corona Virus
Patients are coughing.
The patient is putting droplets – laden with corona virus – into the air.
If inhaled in sufficient volume, that virus is a danger to infect anyone in the environment.
All of the previous dangers of the ICU still exist – the extreme nature of this airborne droplet danger changes how safety should be approached.
Safety Approaches to Air Quality Danger
If a production site works with particulates that can explode, there are clear OSHA guidelines for how to work with that material. In a similar fashion, from working with industrial mix stations – if there is explosion risks, there are basic guidelines from Europe as well in how to manage that risk. For certain flammables under low concentration, the air in a room must turn over 6 times per hour. As those concentrations increase, the air turnover per hour increases – as high as 10 or more times per hour.
If there are enough cough droplets in the air from corona, there is risk for anyone in the room. To reduce that risk, follow established standards:
- Turn the air over. Keep the air moving.
- Reduce the life of droplets by reducing the humidity.
- Filter the air to capture droplets on filter media.
- Change out air filters as often as possible.
- Put out specific air treatment technologies – such as room-air cleaners, ionizers and UV-C light, that are known to kill the virus.
If I was running an ICU and was Concerned About Corona Virus Exposure
I would do everything possible to reduce the indoor air quality risk, which would include:
- Making sure there was lots of air turnover.
- Make sure that air turnover is filtered.
- I would change the filters often for the ICU area. Daily would not be too much.
- I would add room air cleaners (Dyson, Camfil, Austin Air, etc.)
- I would add UV-C lights (and appropriate eye protection when using them)
- I’d do everything I can to make a hostile environment for droplets.
- I’d open windows and try to let in as much sunshine as possible (UV, new make-up air that is uninfected, air flow, and improved evaporation).
1: Question – Do Cruder, Non-HEPA Filters Work?
Yes, they are better than nothing. Fibers in filters have capacity. They catch dirt. Many types of filters only work when they are loaded with dirt – this dust-cake is what creates the actual filter layer.
The virus is also traveling in droplets which can be as large as 100 micron. A MERV 5 filter is 20% efficient, and at MERV 7 is 80% efficient, and it only gets better as it gets higher. If the air is being turned over multiple times per hour, then the there is a high probability that droplet – and the related virus get trapped.