Mar 26 6 tweets 5 min read
I promised I would provide a way to calculate room air exchange, using a simple MERV-13 filter & a box fan. The sweet spot seems to be 6 exchanges per hour. This means all the air in the room is moved through the filter 6 times in 1 hour. 1/6 #ProtectHCWs #ProtectKids #Covid #BA2
First we need to get the volume of a room. It doesn’t need to be perfect! But note units are important. We are using feet/inches here. Use this calculator & input the measurements, A, B, & C as shown in the graphic below. Order is NOT important 2/6 #Filter vcalc.com/wiki/KurtHeckm…
I found a company that did calculations using a box fan on high speed & MERV-13 filters of different depths. The thicker the filter the BETTER the air flow! Strange but true. Note I added the Air Volume based on a 20” square box fan. 3/6 #N95 #BoxFanFilter texairfilters.com/how-a-merv-13-…
Now we will take your room volume you calculated. Multiple it by 6, or the number of times you want to exchange the air per hour. That is the amount of air you need your fan to filter per hour. If that number is less than than the above numbers, you are covered! 4/6 #LongCovid
What do I do if my calculated number from above is greater than the calculated filtration rates??? You take the number from above & divide it by whatever your fans CFH number (based on filter thickness). Round to the next largest whole #️⃣. 5/6 #ventilation #ProtectTeachers
Here is a graphic showing how the set up works. I have a tweet with instructions for making one too! Disclaimer: this is not HEPA filtration, it will DECREASE the viral load in the air this decreasing risk of infection. You NEED to wear an #N95Mask to be fully protected. 6/6

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# More from @RogueVictorian

Mar 22
I want to share an analogy & call to #Hospitals to #ProtectHCWs. 2+ years yet hospitals leave workers open to PREVENTABLE death & disability. They need to held to task & REQUIRED to properly & fully protect their workers. Please join me & share this. #HCWs #Covid #LongCovid (1/3)
#HCWs DESERVE government protections, as do patients! It is unethical for them to continue to skirt proper air filtration & personal protective equipment MINIMUMS. @OSHA_DOL are you listening? #OSHA #P100 #respirators #Ventilate #HEPA #LongCovid #CovidIsNotOver #MaskUp (2/3)
Providing P100 respirators, increasing proper indoor air filtration, & testing workers regularly will help attract & retain staff. In addition to it being the RIGHT THING TO DO! Questions? Contact me #DoTheRightThing #LegislateProtection #ProtectHCWs #Nurses #ProtectRNs (3/3)
Mar 20
Let me tell you a story. By Jan 7, 2020 I knew this was airborne based on the spread occurring in China. By the 21st I had calculated an Ro of 2.4 (turned out to be pretty damned accurate). By the 23rd I called on my fellow healthcare professionals to ensure they had N95s
Or better yet P100 respirators. Then the backlash started. On the 27th I was openly mocked online by an ID doc I had worked with. It snowballed. I was trying to get anyone to listen. I was treated like I was nuts. All I was advising was to stock up on PPE & be prepared
I advised that we figure out a system for increasing mask longevity/reuse at my hospital system. I was dismissed as “reactionary”. The ICU attending & ID MDs went on international vacations in February & March. The hospital admin ignored this. I started posting videos on PPE
Mar 19
I think it’s time to revisit masking with #BA2 & how contagious it is. I am upgrading my recommendations to a P100 @3M respirator. They are less likely to suffer structural damage, meaning I have had them in use for 1 year at a time. That 100 is for 100% an N95 is 95% blocking
Note do NOT use @amazon they have a huge issue with #CounterfeitMasks. The @US_FDA doesn’t seem to be doing their job & cracking down while Bezos lounges on his yacht. I have samples of counterfeit 3M masks I bought off of Amazon. I confirmed with 3M DIRECTLY. So this is serious
This isn’t hearsay but actually provable. Amazon hides behind “tHeY aRE iDepEnDanT coTrAcTOrS” while they rake in that sweet pandemic cash. I recommend you order from @HomeDepot as they buy directly from 3M. I wish I had a better solution. #MaskUp #P100Masks #CovidIsNotOver
Feb 8
I have been asked a number of great questions! So let’s go through each point of my “Care & Feeding of an #N95 #Mask”. Bending or crumbling breaks apart the polypropylene fiber bonds, the magic fiber that filters out & traps the virus using electrostatic charge. @DrEricDing 1/12
Electrostatic charge is like a magnet for the virus. #N95 masks do not rely on layers to filter. 90% of their viral filtering ability is due to this electrostatic charge! If you damage this charge the masks become about as effective as a cloth mask. 2/12 nature.com/articles/d4158…
Washing these masks is destroying them. The agitation breaks apart the polypropylene bonds, opening up the filter, it also permanently destroys the ability for the polypropylene to maintain the electrostatic charge. If they are soiled, please dispose. 3/12