David Elfstrom Profile picture
P.Eng, Energy management, measurement & verification. Born @ 327 ppm CO₂. Safer infrastructure, #ventilation, #CorsiRosenthalBox Also @ https://t.co/SDMtkE22wf & spout & bsky

May 25, 2021, 10 tweets

1/ Dental office #COVIDCO2. The perfectly operable window is closed. 🤦‍♂️ THREAD...

2/ At the end of my visit, in a 144 sqft room with 9' ceilings, the hygienist and myself, it reached 1500 ppm. Overall rebreathed fraction of air from others reached 2.8%. The door to the operatory was open 1 inch.

3/ I believe this is the outdoor air intake for the whole building. Located behind two air conditioner outdoor units.

4/ Other notes: There is a 99 CFM CADR air cleaner in the operatory. It was running on low speed. After discussing with hygienist, she turned it to full speed. This provides 4.5 ACH of equivalent ventilation for aerosol removal.

5/ Hygienist was contact + droplet protection. Double-masking surgical masks. No N95s unless AGP, as per Royal College of Dental Surgeons of Ontario.
This is guidance still as of MAY 2021.
THERE ARE AMPLE SUPPLIES! @BarryHunt008
*BREATHING* IS AN AEROSOL GENERATING ACTIVITY!

6/ I mentioned I can wear my (vertical-fold style) N95 all day without any issue, it's more comfortable than the earloops-style surgical masks.

Hygienist said her N95 (rigid cup style) has to be pulled really tight against her face to get a passing fit.

7/ @rcdso_org, how do you reconcile "put safety first", "prioritize caution and safety" while also placing inventory of PPE of high importance?

8/ @rcdso_org, you had an opportunity to improve protection from respiratory aerosols in line with Health Canada & CDC documentation, and CSA Z94.4-18. But last week (May 19 2021) all you did was add gowns. Gowns.

9/ No change from 6 months ago. I sent the appropriate information by email, tried following up.
🦗🦗🦗
Front line staff are very interested though. As one would be when "working inside a sneeze all day" as @dentalhygieneq1 says.

10/ Someone may point to few, if any, published dental workplace acquired infections with surgical masks.

Or, because of #DropletDogma, when a dental worker acquires COVID-19 do you:

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