Thread by @joeyfox85

Mitigating COVID Transmission in Your Home

You want to have friends over and avoid infection. What tools do you have? Here's a rundown of your options.

1/13

Aside from air quality, your other tools are vaccines, rapid tests and masks/respirators. The more layers the better.

For air quality, your tools are ventilation, filtration, ultraviolet light and humidity. So how do you use them?

2/13

@CPHO_Canada gives a list here (she's leaving out one major thing. Can you guess what it is?)

The 2nd and 3rd option are about running your furnace. I'll start with that.

3/13

https://twitter.com/CPHO_Canada/status/1471869060224794625?s=20&t=ejuG9s1gCwT-LZZD3hOrIw

Your furnace will supply about 30-70 cubic feet per minute per room. That's a tiny amount and not sufficient for mitigation. It's still worthwhile to ensure the air coming from your furnace is clean and run it. You can clean the air in the following ways:

4/13

-Attach an energy/heat recovery ventilator
-Upgrade filter to MERV-13 (my personal choice)
-Attach a HEPA filter to the furnace
-Place a UV lamp in the furnace (unsure how effective)

Do at least one of these and run your furnace.

5/13

Humidity

Humidity can be a helpful tool. Ultrasonic humidifiers can release mold, bacteria and other particles into the air. The best thing is a steam humidifier with distilled or reverse osmosis water. I have one attached to my furnace. Don't humidify past 40% RH.

6/13

The rest of the mitigation happens in each room:

Ventilation - windows are your tool. If it's cold, keep them cracked. You can boost air coming into the home by running an exhaust fan or making your own exhaust fan like Joe. (Be like Joe👍)

7/13

https://twitter.com/joeolivermd/status/1549410534793134081?s=20&t=WhKe_AsF4S2_9_CryVRdSw

If you are exhausting air out, make sure there is a place for air to come in (open window). Your kitchen range hood is powerful, but usually loud. Bathroom fans are weak and not that effective for this.

8/13

Filtration

Run a HEPA filter or a DIY Corsi-Rosenthal Box. Not much more to say.

9/13

UV

If we want to get serious about mitigation, this is the best tool. The evidence we have is a 15 W far-uv lamp in a dining room gives you 30-60 air changes per hour. 1 lamp > 4 CR Boxes. I would use it if someone is symptomatic or when having guests (with consent).

10/13

Higher power far-uv will be more effective, but you need to do your research to ensure you aren't exceeding daily threshold exposure levels. You are very unlikely to exceed them if there is a 15 W lamp in your ceiling.
nature.com/articles/s4159…
11/13

Short range transmission

You need to dilute the concentrated air in your breathing zone with air from the room quickly. The way you do that is with increased air speed. Larger fans (ceiling fans) can do this more quietly. Smaller fans will be louder.

12/13

You can also use HEPA filters/CR Boxes to increase the airspeed in the room (they have fans). Combine that with effective air cleaning (windows, HEPA/CR box, far-uv) and you will create a VERY low risk environment. No guarantees, there is always some risk.

13/13

For stopping COVID in your home, you need extra tools. See this thread.

https://twitter.com/joeyfox85/status/1508527893567131652?s=20&t=WhKe_AsF4S2_9_CryVRdSw

For basic indoor air quality in your home (not mitigating COVID), see this.

https://twitter.com/joeyfox85/status/1586878830391836674?s=20&t=PwZcJe7W90vfWGQgpXrHGQ