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Why Masks Don't Work in Schools

If cloth/surgical masks are ineffective and kids have been safe in school this whole time, then masks were not necessary.

Science of Masks: News

What can masks do? Part 1: The science behind COVID-19 protection

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October 14, 2021

"The public should not rely on typical cloth or surgical masks to offer them much time beyond 15 minutes in a shared space with potential sources, even if others are also wearing masks. Wearing a non–fit-tested respirator allows about an hour of time inside a shared space even if no one else is wearing a mask or respirator."

The Case Against Masks at School

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January 26, 2022

Imposing on millions of children an intervention that provides little discernible benefit, on the grounds that we have not yet gathered solid evidence of its negative effects, violates the most basic tenet of medicine: First, do no harm. The foundation of medical and public-health interventions should be that they work, not that we have insufficient evidence to say whether they are harmful.

What can masks do? Part 2: What makes for a good mask study — and why most fail


October 15, 2021

It is time to lower the unrealistic expectations about masks—or any single intervention. Public health messaging needs to be focused on many interventions, starting with those at the top of the hierarchy. Masks offer very limited source control and personal protection and should not be considered a replacement for vaccination or equivalent to interventions such as limiting time and the number of people in a shared space or improving air movement.

The Case Against Masks In Schools

Students with Masks

August 20, 2021

  • When Do Masks Come Off?

  • The Risk To Children Is Low

  • Masking Children Does Not Reduce The Risk

  • The Case For School Mask Mandates Is Weak

  • Most European Children Do Not Wear Masks In School

The Time to End Los Angeles’ General Mask Mandates is Now

Children coloring

February 11, 2022

Mask mandates for children are the most egregious. COVID-19 is less of a threat to children than accidents or the common flu.

Cloth Masks Are Useless Against COVID-19

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August 25, 2020

The idea that cloth masks will protect anybody from contracting COVID-19 is magical thinking, Lisa Brousseau, ScD, expert on infectious diseases, Professor (retired), University of Illinois at Chicago, tells Infection Control Today.


Infection = Time + Concentration

The filtration and fit of the mask is only half of the story. The rest is based on how long an infected person can be in a classroom with an uninfected person.

For cloth and surgical masks, it is mere minutes. ACGIH created this table before Delta (2X more contagious than original strain) and Omicron (2-3X more contagious than Delta).

What this means is a cloth or surgical mask protects you for mere minutes, making the wearing of masks in a classroom for 7 hours per day entirely pointless.

This table has been revised below for Omicron, or you can calculate it at the website prepared by indoor climate expert Asit K Mishra linked here:

Science of Masks: Who We Are
Science of Masks: Welcome

Household COVID-19 Risk and In-Person Schooling

Science: June 4, 2021

School-based mitigation measures are associated with significant reductions in risk, particularly daily symptoms screens, teacher masking, and closure of extracurricular activities.

Household COVID-19 risk and in-person schooling
Science of Masks: Welcome

What the CDC Says About Surgical Masks

Face Seal Fit



Does NOT provide the wearer with a reliable level of protection from inhaling smaller airborne particles and is not considered respiratory protection


Leakage occurs around the edge of the mask when user inhales

Science of Masks: What We Do

Studies & Data

Evidence on Masking Children in School

Classroom Lecture

Age-dependency of the Propagation Rate of Coronavirus Disease 2019 Inside School Bubble Groups in Catalonia, Spain

November 2021

In Spain, the use of masks in the school for students older than 6 is mandatory. Therefore, young children between 3 and 5 years are not required to use masks in schools. 
The low values of R* we obtained for preschool period (3–5 years), with students not wearing masks inside the bubble group.

Minimal transmission of SARS-CoV-2 from paediatric COVID-19 cases in primary schools, Norway, August to November 2020

January 7, 2021

Use of face masks is not recommended in schools in Norway. We found that with the IPC measures implemented there is low to no transmission from SARS-CoV-2–infected children in schools. This finding strengthens national guidelines to adjust IPC measures according to the community transmission level [18], rather than closing primary schools for on-site teaching.

Image by Mira Kireeva
Happy Team Posing

COVID-19 Mitigation Practices and COVID-19 Rates in Schools: Report on Data from Florida, New York and Massachusetts

May 21, 2021

We find higher student COVID-19 rates in schools and districts with lower in-person density but no correlations in staff rates. Ventilation upgrades are correlated with lower rates in Florida but not in New York. We do not find any correlations with mask mandates. All rates are lower in the spring, after teacher vaccination is underway.

Two New CDC Studies on Masking in School

September 25, 2021

Two studies in MMWR claim to provide evidence that policies mandating masking children in school lowers rates of sars-cov-2 spread among children due to school.  Both suffer from limitations that preclude causal claims.  I will review both here.


The CDC's Latest Study on Masks is Purposeful Misinformation

February 7, 2022

The CDC posted this graphic, which will be used to inform public policy, local school boards, politicians and corporate executives, and purposefully included a result that was not statistically significant.
That’s misinformation.
It’s an intentional attempt to deceive the public by utilizing a result that did not meet the bare minimum requirements to be “significant” in order to push an agenda.

Preliminary Results of North Dakota School Mask Study

February 13, 2022

The latest update from our Fargo, ND K-12 masks study now w/crossover
FPS district 🔵 mask mandate, 11,346 students
WF district 🟡 masks optional, 12,208 students
Same municipality & county
Y axis: % students actively + for covid
vertical green line = FPS 🔵 went masks optional

Science of Masks: News
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