Mike Hoerger, PhD MSCR MBA Profile picture
Jul 19, 2022 12 tweets 9 min read Read on X
Top 10 tips everyone should know about wearing #N95 & #elastomeric masks.

What did I miss?

THREAD! Image
Tip #1: Masks buy time. Context matters too: Ventilation (HVAC/outdoor air), filtration (HEPA), & ⬇️ people buy more time.

The longer you’ll be someplace or the worse the context, the better the mask you’ll need.

In a “typical” setting, you might expect this (per @akm5376): Image
Tip #2: If you’re going to be someplace a long time (home, office, hospital, wedding), open windows, add #HEPA, turn HVAC from ‘auto’ to ‘on' & do testing.

BOOM, you just improved your mask. Better context = less work for the mask.

Tip #3: These are my three fav N95s. The Aegle & 3M Aura are good for most adult size faces. The Vflex is good for larger faces. I think 80-90% would be happy with the Aura.

What’s your fav #N95 and why?

Tip #4: Have a unique concern? There’s an N95 for you. Just ask.

For example, a lot of people like the Airgami if they have COPD or other breathing challenges.

The Readimask is good for MRIs, haircuts, or dental visits.
Image
Tip #5: Do a quick #N95 seal check each time. Fit the nose piece using both hands. Exhale a deep breath to check for obvious leaks.

Read the instructions that came w/them, e.g., the 3M Aura or Vflex should be pulled back taut under the chin, not loose.

cleanaircrew.org/masks/#How_to_…
Tip #6: At low cost, you can fit-test an N95.

Buy a nebulizer & sweet (called FT-31) or bitter (FT-32) fit testing solution. The nebulizer vaporizes the solution. If you can taste it, your mask has gaps.



Tip #7: N95s are great, but for a better fit, try an “#elastomeric.”

That’s just a reusable elastic-band type mask.

Twitter search “elastomeric” for recs & sizing. Good ones: GVS models ($), @DentecSafety ComfortAir ($), @flo_mask ($$, adult & kid’s size), & Envo mask ($$) Image
Tip #8: Always buy directly from the manufacturer, a nonprofit like @projectn95, or a verified sourced. For example, Amazon sells a ton of fakes, but GVS is verified to sell authentically via Amazon. Do your homework.

Any questions on where to buy?

projectn95.org
Tip #9: Share the wealth. You can give away N95s to your family, friends, co-workers, patients, clinicians, & community.

Share these tips too. RT 🔁or post these tips on legacy platforms like Facebook Image
FYI, I have no COIs, including no investment in any company listed. I’m a multidisciplinary scientist. My goal is to pass along advice from experts in a way that’s more relatable to communities.

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More from @michael_hoerger

Aug 21
During times like these when COVlD transmission heats up in the U.S., expect to see a lot more angry outbursts for three central reasons.

First, "displacement," or people trying to deny the reality of their anxiety by taking it out on other people....
Second, a lot of people can sustain a strong denial of reality about the ongoing pandemic during lulls. They suppress the existence of COVlD waves and excess deaths, disability, and retirements.

During waves, those defenses burst. Loss of control = anger...
Third, a lot of people (many reading this) understand COVlD correctly & experience righteous indignation during COVlD waves. We quite reasonably do not like all of the unjust and gratuitous suffering.

I find it helpful to channel that intensity into helping other people....
Read 6 tweets
Aug 19
I submitted my comment to endorse universal high-quality masks (respirators) in healthcare. Today is the final day.

Alt text continues in the following posts. RE: Z94.4, Selection, use, and care of respirators (New Edition)  Dear Colleagues,  As the director of a population science program at a major U.S. cancer center, I strongly endorse this draft proposal to increase the use of high-quality well-fitting masks (respirators) in medical settings. I will comment on the relevance of this proposal mainly for cancer care. In the U.S., cancer care is commonly more organized than other specialty care and, thus, often leads the way on policy initiatives, which then translate to other elements of care over time.  1. COVID-19 continues to cause excess dea...
They put forth projections, with the most granular detail for the U.S. and U.K., suggesting excess deaths will persist through at least 2033. Their projections do not show excess deaths stopping in 2033; that is simply the final year of their current analysis. Moreover, while they provide the most data for the U.S. and U.K., their analysis suggests a more general trend throughout the globe. The COVID-19-associated excess deaths are commonly identified as cardiovascular and cancer causes of death.   Swiss Re Institute. (2024). The future of excess mortality after COVID-19. https://www.swissr...
Alt text continued 2. The SARS-CoV-2 virus that causes COVID-19 continues to transmit at high rates worldwide. Overall, 28 nations continue to use wastewater surveillance to monitor SARS-CoV-2 levels. A directory is available at the dashboard that I oversee (pmc19.com/data). In the U.S., we are currently experiencing our 11th wave of transmission. Many nations are experiencing annual or twice annual waves of transmission.
Alt text continued 3. International consensus standards identify a broad range of patients at known high-risk of severe outcomes of COVID-19. The largest group at known high risk of severe outcomes is patients with cancer. Other diagnoses associated with above average risk include people undergoing transplants or receiving dialysis, and patients with any of these diagnoses: immunodeficiencies, renal disease, systemic-immune mediated or single-site immune-mediated inflammatory conditions, asplenia, anatomical barrier defects, pregnancy, and diabetes. These findings underscore the importance of standards in hea...
Read 7 tweets
Aug 16
🚩🚩🚩
As a vigorous defender of #CDC data, their switch from using normalized to non-normalized COVlD wastewater surveillance data today harms data quality.

"Normalizing" means accounting for basic confounders like rain levels. It is a choice to use worse data.
1/5🧵 Image
Historically, the CDC data have correlated near-perfectly with similar metrics, such as Biobot's wastewater estimates (still active) or the IHME true case estimates (through mid-2023).

The changes reduce those correlations. It's like going from an A+ to a B.

2/5🧵
You can readily see the loss of data quality in the PMC "whole pandemic" graph (preview shown, subject to change) with choppier waves, caused by the CDC adding extra noise to the data and applying retroactively from BA.1 Omicron to present.

3/5🧵 Longitudinal graph of the pandemic waves. Notice how they start becoming choppier in 2022, as a result of today's changes at the CDC
Read 5 tweets
Aug 12
PMC COVID Dashboard, August 11, 2025 (U.S.)

The CDC says transmission is heating up.

"Very High" (3)
🔺Guam
🔺Hawai'i
🔺Louisiana

"High" (12)
🔺Alabama
🔺Alaska
🔺California
🔺Colorado
🔺Delaware
🔺Florida
🔺Indiana
🔺Mississippi
🔺Nevada
🔺S. Carolina
🔺Texas
🔺Utah

🧵1/12Heat map from CDC data. High/Very high states noted in post
Transmission is highest in these regions. Graphics note the CDC levels and PMC prevalence estimates.

🔥Louisiana (Very High): 1 in 19 actively infectious
🔥Guam (Very High): 1 in 26
🔥Hawai'i (Very High): 1 in 28
🔥Texas (High): 1 in 45

🧵2/12 Graphics show heat maps and prevalence estimates, noted in the post
Statewide transmission remains "High" in Florida, according to the CDC. PMC estimates 1 in 50 actively infectious.

Several cities report "Very High" transmission. Several sites are offline.

🧵3/12 Heat map and prevalence estimate noted in the post
Read 12 tweets
Jul 29
PMC COVID Dashboard, July 28, 2025 (U.S.)
🧵1/12

PMC estimates 400,000 new daily infections. 1 in 118 people actively infectious.

Weekly stats:
🔹2.8 million infections (>40x reported cases)
🔹>140,000 resulting #LongCOVID cases
🔹>1,000 resulting excess deaths Heat map Very High: Louisiana, Guam High: Hawai'i, Florida
PMC COVID Dashboard, July 28, 2025 (U.S.)
🧵2/12

Please excuse any typos and delays. Any time Mimal's boot turns deep red, we're doing local outreach in addition to dashboard work, etc.

If you don't know Mimal yet, you won't be able to unsee them.
es.wikipedia.org/wiki/MIMALDeep red boot = Louisiana
Minnesota (M), Iowa (I), Missouri (M), Arkansas (A), Louisiana (L) = Mimal  Louisiana is the boot.   Sometimes depicted with Kentucky fried chicken on a Tennessee pan.
PMC COVID Dashboard, July 28, 2025 (U.S.)
🧵3/12

It's HOT COVID SUMMER in the Deep South. No geographic/political prejudices, see next.

Covid is burning through Guam, Louisiana, Florida, and Texas (underestimate due to sites down). Louisiana: 1 in 32, Very High (CDC)
Texas: 1 in 98, Moderate (underestimate, CDC)
Guam: 1 in 25, Very High (CDC)
Florida: 1 in 59, High (CDC)
Read 12 tweets
Jul 25
U.S. CDC numbers just released. Good news (for those not in Louisiana). "Only" a 5% national increase.

2025 has closely tracked with summer 2023 transmission. A 12-13% increase would have been expected based on those numbers. That said... Up: Midwest, Northeast Down: West, South
real-time data have been prone to retroactive corrections. This is frustrating, of course, because it leaves people making decisions based on data that are only of good quality when 2 weeks old.

If we saw a 12% increase this week, I'd say look at 2023 for a glimpse...
at the future. Instead, I would consider these plausible scenarios:
🔹Wave still similar to 2023
🔹Later wave with schools more implicated
🔹Something temporarily much better

Of course, temporarily better often means...
Read 6 tweets

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