Editor's Note: Part 1 of a two-part commentary explains the differences in cloth face coverings and surgical masks, the science of respiratory protection, and the hierarchy of disease controls. Part 2, to be published tomorrow, will outline what makes a good mask study and why so many fail.
That was followed by substantial misinformation and misunderstanding about the role of cloth face coverings, surgical masks, and respirators in preventing SARS-CoV-2 spread. Then we had misunderstandings and poor messaging about the efficacy of different interventions, the effectiveness of one intervention versus another, and why interventions should be considered in a particular order or hierarchy.
So it is completely understandable that the public and even the scientific community expresses confusion over how well masks protect against a respiratory disease like COVID-19. In part 1 of this commentary we will cut through the murk by:
(For simplicity, we will broadly use "masks" to refer to both cloth face coverings and surgical masks, unless this difference is specified. Respirators like N95s are not considered to be masks [see sidebar at right]).
It is critical to balance the need for rapid information sharing with rigorous and methodical scientific investigation during a pandemic.1 Early in the pandemic, messaging about masks compromised the latter for the former with the understanding that, with time, more data would become available to make clear the role that masks, in combination with other interventions, might play in limiting person-to-person transmission of SARS-CoV-2.
The data are clear that most cloth face coverings and surgical masks offer very limited source control (protection of others from pathogens by limiting emissions from an infected person) and personal protection against small inhalable infectious particles and should not be considered a replacement for other, more effective methods of reducing one's exposure to SARS-CoV-2, such as vaccination and good ventilation.
Droplet transmission, or propulsion of large particles from sneezing or coughing into the nose, mouth, and eyes of those nearby, could be prevented by erecting barriers between people, physical distancing, and wearing masks with filters that capture large particles. None of those interventions, however, is effective for smaller inhalable particles, which are the predominant size created by people in high concentrations when breathing, talking, singing, etc. Smaller particles stay in the air for long periods (hours), are easily distributed by diffusion and air currents throughout a space (thus negating the effects of physical distancing), and can carry many virions. Masks have filters that do not efficiently capture smaller airborne particles and leave gaps around the mask that allow small particles to leak both in and out.3,6
The interventions that prevent aerosol inhalation are those that reduce the concentration of small particles in a shared space and the time someone spends in that space inhaling those small particles. Particle concentration can be reduced by having fewer people in the space, sharing space for shorter periods, using ventilation that removes particles quickly near the source, and using source controls (masks and respirators) with good filters and fit.
Early in the pandemic, CIDRAP published an article describing the differences between cloth face coverings, surgical masks, and respirators.6 The most important features of anything worn on the face to prevent the emission of respiratory particles (source control) or protect the wearer from inhaling infectious particles (personal protection) are filter efficiency, breathing resistance, and fit, in that order.
The CIDRAP article describes appropriate methods for testing these three important variables and the published data for each type of mask or respirator. At that time there were no standards for cloth face coverings and only a small number of surgical masks were tested for filter performance (but not breathing resistance or fit).
A 2021 study by Lindsley et al,7 which evaluated outward leakage of a range of face coverings, masks, and respirators on a mannequin, filter efficiency and breathing resistance using appropriate methods, and fit (inward leakage) on human subjects, is perhaps the best recent study to demonstrate the differences between cloth face coverings, surgical masks, and respirators.
ACGIH (formerly the American Conference of Governmental Industrial Hygienists), a professional scientific organization dedicated to advancing occupational and environmental health, created a COVID-19 Task Force in November 2020, which developed several fact sheets for workplace health and safety, including a table that illustrates the degree of protection offered by different types of masks in comparison to a respirator.15 We have modified this table to demonstrate that an N95 FFR, even if not fit-tested, offers more benefits as both source control and personal protection than any mask (Table 1; French translation available here).
It is understandable that masks have come to play an outsized role in people's minds, because they appear to offer a relatively easy solution that, unlike other interventions, does not significantly interfere with everyday activities. It is easy to see whether someone is wearing a mask, and it is easy to blame the people who do not for spreading infection.22 Mask wearing (or the lack thereof) provides an easy target for blame, when there are many less observable or measurable variables that could be responsible for infection.
Also, it is easier to require people to wear masks in comparison to other, more effective interventions, such as vaccination, limiting the number of people or the time they spend in a shared space, or improving the ventilation in that space. Wearing masks provides an oversized illusion of control over a difficult-to-contain and still largely unknown disease.
Cloth and surgical masks offer a very limited degree of source control, because, while they limit the number of larger respiratory particles in a space, they do not prevent the emission of most small particles (aerosols) exhaled during breathing, talking, singing, coughing, or other respiratory actions. Because masks offer limited source control and much more limited personal protection, their effectiveness can be improved only by combining them with other interventions.
None of these interventions, absent eliminating contact with other people, is effective on its own. But the greater the number of interventions implemented, the lower the risk of person-to-person transmission.22 Some interventions, such as vaccines, are more effective than others, such as masks. As discussed above, anyone wearing a mask should be aware that the longer they spend in a shared space with other people, the greater the risk of being infected.
Today people wear masks to hide their identity but also to impersonate another real or imaginary being. All Neolithic cultures in the Near East made masks. Why? What were the rituals and ideas behind the masks?
Eyes, nose, and mouth are again depicted, and the back is concave. From its find context, a middle-PPN B date can be assumed for this mask. Nevalı Çori furthermore has become well known as the first place where an important characteristic element of PPN architecture of the region was discovered: T-shaped, apparently anthropomorphic, pillars. These link it to another nearby site that also has produced a number of comparable masks: Göbekli Tepe.
Three of the masks found at Göbekli Tepe have similar styles to the example from Nevalı Çori, with non-individualized faces. However, at Göbekli Tepe the mouth is not depicted, while the Nevalı Çori mask almost gives the impression the face is screaming. Together with the finds from other sites, a large repertoire of masks in different styles is suggested. All types, with and without mouths, more individualized or abstract, are also well attested for in the large repertoire of limestone sculpture found at Göbekli Tepe.
They are orientated towards the central pillars and evoke the association of a gathering. Naturalistic anthropomorphic sculpture, which may partly depict masked people, is smaller and intentionally fragmented. The stone masks are strongly related to this category through form and deposition treatment.
If we assume that the stone masks are miniature or supra-sized representations of real organic masks worn by humans, they might attest that ritual activity at Göbekli Tepe and other sites included masquerades, where people acted out parts of a complex mythology. When enclosures were put out of use, masks and miniatures were buried with them, freezing rituals in time and space.
During the early Neolithic in the Near East, masks and masking played a significant role in rituals re-enacting mythological narratives closely related to death, taking place at sites with special purpose buildings and rich iconography. This importance apparently justified the time-consuming and complicated manufacture of these paraphernalia as well as miniature and larger-than-life-sized representations. A small number of masks in stone are all what remains of what was likely a widespread Early Neolithic tradition of ritual masquerade.
The latest CDC guidance puts nearly 70% of the U.S. population in low or medium risk areas, and residents are no longer expected to wear a mask. The vast majority of states in the U.S. have lifted or plan to lift mask mandates.While many Americans welcome the loosening of pandemic-era safety rules, people who are higher risk feel forgotten and left behind. Johnnie Jae is an Indigenous journalist and public speaker; Charis Hill is a disability activist; and Cass Condray is a university student. The three explain what it's like to be immunocompromised and chronically ill during the pandemic, and what can be done to allow them to better live their lives.In participating regions, you'll also hear a local news segment to help you make sense of what's going on in your community.Email us at email@example.com. 2b1af7f3a8