Featured image for article

The Twelve Days of Mask Mess: Day 12

For the twelfth day of mask mess, we got these:

Konda A, Prakash A, Moss GA, Schmoldt M, Grant GD, Guha S.

Aerosol Filtration Efficiency of Common Fabrics Used in Respiratory Cloth Masks. ACS Nano (2020)14(5):6339-6347.

Received April 18, 2020, this study tests the aerosol filtration of various fabrics that are used for cloth masks given the pandemic-driven “significant demand” for face masks , including “cloth masks, many of them homemade.” Konda et al. test the fabrics by using a generator that creates aerosol particles and using a blower fan to draw air through containing the particles. They tested “over 15 natural and synthetic fabrics that included materials such as cotton with different thread counts, silk, flannel, and chiffon,” “a N95 respirator and surgical masks” for comparison, and also “multiple layers of a single fabric or a combination of multiple fabrics for hybrid cloth masks.”

Konda et al. found a wide range in filtration efficiencies for the various fabrics, “rang[ing] from 5 to 80% and 5 to 95% for particle sizes of <300 nm and >300 nm, respectively.” Hybrids had the higher efficiencies, which the authors attributed to “a combined effect of mechanical and electrostatic-based filtration.” Multiple layers and cotton with high thread counts were also more effective. Given such a broad range, they summarize with can and potentially, that “cloth masks can potentially provide significant protection against transmission of particles in the aerosol size range.”

Also qualifying their findings: Konda et al. find masks lost most of their effectiveness if there were “gaps (as caused by an improper fit of the mask),” which “can result in over a 60% decrease in the filtration efficiency.”

This issue of gaps and “leakage” matter to their findings. “It is important to note,” they write, “that in the realistic situation of masks worn on the face without elastomeric gasket fittings (such as the commonly available cloth and surgical masks), the presence of gaps between the mask and facial contours will result in ‘leakage’ reducing the effectiveness of the masks. It is well recognized that the ‘fit‘ is a critical aspect of a high-performance mask.” They later reiterate the problem of “air leaks that arise due to improper ‘fit'” and it being “critically important” for mask design to take mask fit into account.

There is nothing in the study about government officials ordering mask-wearing, regardless of type and filtration efficiency. The authors do foresee “Opportunities for future studies,” such as “cloth mask design for better ‘fit'” as well as “the role of factors such as humidity (arising from exhalation) and the role of repeated use and washing of cloth masks.” (Other studies put forward by the Cooper administration have warned against the dangers of masks becoming moist from exhalation due to long use or in physical activities or exercise.)

Does this study support Cooper’s extreme exercise of power?


Probable effects (“can” “potentially” provide) of mask efficiency with such wide ranges (“5 to 95%” that could be cut by 60% depending on fit) cannot be the basis for extreme emergency orders.

This study was about testing mask filtration efficiency, not about calling for restrictive government policy. If Cooper were to recommend mask wearing rather than force them on people and have it policed by local law enforcement and citizen informants, such a study could be used to inform their choices. Cooper’s order, however, even expressly mentions using towels for homemade masks.

Cooper still has — and has always had — the option to treat North Carolinians as free-thinking adults and use his office and state health department “to recommend, to persuade, even to urge people to adopt practices such as wearing face coverings that they believe is healthy.” Instead, he has repeatedly resorted to issuing extreme emergency orders. Cooper’s own science doesn’t support going to those extremes.

Hatzius et al.

Face Masks and GDP. Goldman Sachs Research

Published June 29, 2020, this study was not included in the Cooper administration’s list. It is, however, one of the five “examples of studies studying the effectiveness of face coverings” that Cooper cited in his executive order tightening face mask restrictions against people.

Writing for Goldman Sachs, Hatzius et al. are keenly interested in avoiding government lockdowns, such as what Cooper instituted in his “Stay-At-Home” executive order of March 27 and what Cooper is flirting with reinstituting with his most recent “Modified Stay-At-Home” order of December 8. They acknowledge that “investors … worry about renewed broad lockdowns with large negative effects on GDP.”

Hatzius et al. see that “many European countries now have national mask mandates in place,” and also that “much of East Asia has strong social norms of mask wearing when sick and during pandemics. They wonder, “How effective would a national mandate be in pushing mask usage to Southern European or East Asian levels?” They therefore seek to ask three questions about whether the U.S. should have a national mask order to begin their analysis:

First, how effective is a face mask mandate in increasing face mask usage? Second, does increased face mask usage lower virus transmission, and if so by how much? And third, how economically valuable is a face mask mandate in terms of reducing the need for broad lockdowns with their well-documented negative effects on GDP?

Using Lyu and Wehby’s findings (see the first study cited here), they “estimate … that a national mandate could raise the percentage of people who wear masks by 15 pp [percentage points] and cut the daily growth rate of confirmed cases by 1.0 pp to 0.6%.” From that they argue the following:

These calculations imply that a face mask mandate could potentially substitute for lockdowns that would otherwise subtract nearly 5% from GDP.

Hatzius et al. repeated mention the mask mandate as a “substitute” for lockdowns, because lockdowns would “hit GDP”/”subtract nearly 5% from GDP.”

Does this study support Cooper’s extreme exercise of power?


The assumptions behind this study come from Lyu and Wehby, which as discussed before rely on probable estimates based on their model’s predictions of effects “over time,” which over time have proven elusive. Lyu and Wehby also cautioned that their estimates should be “viewed cautiously.” Running with a different study that doesn’t view those findings cautiously cannot be the basis of extreme emergency orders.

Furthermore, Hatzius et al. also rely on probable effects (calculations “imply,” mandate “could” “potentially” substitute), with respect to a national mask order. None of that can justify an extreme emergency state order.

Changing the culture to “push” North Carolinians to adopt “social norms” of other cultures is no business of extreme emergency orders.

If we allow that their implied possible effects of a mask order would apply to a state, and that it could potentially keep a governor from locking down the economy again (and thereby restrain himself from doing serious damage to state GDP), shouldn’t Cooper be sobered by their warnings about economic damage from lockdowns? Instead, the governor flat-out warned of returning to lockdowns in announcing the very order that cited this research, and he has continued to do so ever since, warning “We’ll do more” even after dropping the latest curfew/modified stay-at-home order.

Click for more of the Twelve Days of Mask Mess series. 

Jon Sanders / Director of Regulatory Studies

Jon Sanders studies regulatory policy, a veritable kudzu of invasive government and unintended consequences. As director of regulatory studies at the John Locke Foundation, Jo...

Reader Comments