We stopped COVID in our home! My wife felt sick early last week and then tested positive (RAT). Everyone in our family is now negative. My kids and I never got it. We didn't resort to extreme measures like isolation or kids wearing N95s all day. This is how we did it:
1/11
We followed public health advice:
-wore comfortable cloth masks
-washed our hands frequently
-cleaned and disinfected - especially the toys
-practiced safe physical distancing
-put up plexiglass barriers as an extra precaution.
Just kidding. That's not how it's done.
2/11
#COVIDisAirborne . Focus on keeping the air clean and you can stop the spread. These are the measures we took:
Vaccines - we're all fully vaccinated (including boosters) except my 3 yo. My 4 month old had 2 doses in utero. My 6 yo has 2 doses.
3/11
Masks - I wore the CAN95 or CAN99 with ear loops. My wife wore a KN95 when she could, otherwise she wore a surgical mask + knot & tuck. It fits her well.
Filtration - We have 1 large #corsirosenthalbox in the main area and 3 minis in the bedrooms.
The CR box is right beside where we eat and where the kids play/watch TV. We turned it up to medium speed for meals. My wife either ate in a different room or waited until we left and ate by herself. We kept windows cracked intermittently.
5/11
Humidifiers - we ran humidifiers in all the bedrooms every night. Tried to keep the home at 40% RH but because of the cold weather, it stayed around 30%.
With older kids, we could have had them stay in their rooms all day, but that wasn't possible for us.
6/11
I moved into the guest room and kept the window cracked. I made sure a room was aired out (3 air changes) before removing my mask. If the kids wanted to play in the basement, I brought one of the mini CR boxes down.
7/11
We had a disadvantage - an unmasked, unvaccinated 3 yo. It's been -10 deg C, couldn't open windows for long or go outside. But we have a 4 bedroom single family home which helped.
8/11
There's always an element of luck - how contagious someone is - but what we did worked.
-Vaccines work
-Well fitting medical masks work
-Filtration works
-Humidifiers work
My wife's case was mild - she felt fluey and achy for a few days - that's it. Many don't have that.
9/11
I've seen horror stories about how contagious this can be - e.g. across hallways in hotels with brief exposure - but those aren't the norm. Those stories do a disservice by making it seem impossible to stop this. It's not.
10/11
Focus on clean air and proper masking (N95s). It can be stopped. Vaccines, humidifiers, filtration, open windows, go outside, respirators...Infection isn't inevitable.
11/11
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What are good CO2 levels and what can you do if they aren't good?
When people breathe out they expel CO2. Depending on the level of ventilation, this can be exhausted and the CO2 levels will stay low (good ventilation) or if it isn't good, the CO2 will build up and rise.
There is no hard cutoff with the different levels, but here is a guide.
<800 ppm is quoted a lot, but in my experience, classrooms can be much higher. Up to 1500 ppm can occur with ventilation not working perfectly (very common). > 2000 happens with bad ventilation.
2/7
CO2 levels measure how much air is shared or rebreathed. @DavidElfstrom prepared a table comparing CO2 levels to the % of rebreathed air. The more rebreathed air, the higher the risk of airborne transmission.
1 air change only removes 63% of the virus particles. Why? (Warning: Math)
Thought experiment 1:
Start with 100 virus particles (VPs).
Remove all the air in the room (100 VPs).
Refill the room with air.
You have 0 VPs left - 100% removal.
1/5
Thought experiment 2:
Start with 100 virus particles (VPs).
Remove half the air in the room (50 VPs).
Refill half the room with air and let it mix.
You have 50 VPs left.
Remove half of the air again (25 VPs).
Refill the room.
You have 25 VPs left - 75% removal
2/5
Thought exp. 3:
Start with 27 VPs.
Remove 1/3 of the air (9 VPs).
18 VPs remain. Refill the room.
Remove 1/3 of the air (6 VPs).
12 VPs remain. Refill the room.
Remove 1/3 of the air (4 VPs).
8 VPs remaining, 19 removed total.
Refill the room.
Case study in bad school ventilation (not from work or my kids’ school):
There were outbreaks where most of the class got infected. There was a new ventilation system installed 2 years ago. It should have been great ventilation. I asked them to get a CO2 monitor to check. 1/4
CO2 was more than 2000 ppm throughout the day! I checked the airflow with a tissue and a broomstick. No airflow. 2/4
What happened?
It’s a VVT system that was designed to reduce airflow when heating wasn’t needed. Should be set to have a minimum amount of air. However: mechanical installed it with factory settings, air balancer only measured maximum airflow, consultant didn’t verify. 3/4
It's just a fan and a filter, but there's a lot to discuss.
Table of Contents
4/ HEPA Filter Myth vs. Fact 5/ Comparing HEPA Filter and CR Box 6/ HEPA Filter Selection for Classrooms
Continued...
2/ TOC Continued
7/ HEPA Filter for your Home 8/ Calculating What HEPA Filter Does 9/ Windows and HEPA Filters 10/ Convincing Schools to Put in a CR Box 11/ Mini CR Box 12/ They [Don't] Blow the Virus Around 13/ HEPA Filters Don't Interfere with Ventilation
3/ TOC Continued
14/ Myth: HEPA Filters not Required with Good Ventilation 15/ MERV-13 Filter in Air Handling Unit vs. Space HEPA Filter
Plexiglass can be useful in specific situations, but harmful in others. To know why, you need to know the different methods of airborne transmission.
1/7
Plexiglass stops short range transmission as it prevents you from breathing in the concentrated aerosols directly leaving the infected person's mouth/nose.
3/7