I thought masks wouldn’t protect against a virus (being tiny) but might help slow the spread to others by stopping spittle/moisture filled with virus from covering real world objects.
How do they help you if no one else is wearing them?
Because the virus is transmitted via spittle/moisture from other people not wearing masks. The virus doesn’t just hang out in the air on its own; it’s suspended in aerosol particles.
To reduce spread of respiratory diseases, we need to understand the mechanisms of spread. There is strong and consistent evidence that respiratory pathogens including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), respiratory syncytial virus (RSV), influenza, tuberculosis, and other coronaviruses such as MERS and SARS-1, are transmitted predominantly via aerosols. Infected individuals, whether symptomatic or not, continuously shed particles containing pathogens, which remain viable for several hours and can travel long distances. [Emphasis mine.] SARS-CoV-2 is shed mainly from deep in the lungs, not the upper respiratory tract, and the viral load is higher in small aerosols (generated in the lower airways) than in larger droplets (generated in upper airways). Whereas large respiratory droplets emitted when people cough or sneeze fall quickly by force of gravity without much evaporation, those below 100 µm in diameter become (bio)aerosols. Even particles tens of microns in diameter at release will shrink almost immediately by evaporation to the point that under typical conditions they can remain airborne for many minutes. In contrast with droplet transmission, which is generally assumed to occur via a single ballistic hit, the risk of airborne transmission increases incrementally with the amount of time the lung lining is exposed to pathogen-laden air, in other words, with time spent indoors inhaling contaminated air.
Respiratory infections may theoretically also be transmitted by droplets, by direct contact, and possibly by fomites (objects that have been contaminated by droplets), but the dominant route is via respiratory aerosols. The multiple streams of evidence to support this claim for SARS-CoV-2 include the patterning of spread (mostly indoors and especially during mass indoor activities involving singing, shouting, or heavy breathing), direct isolation of viable virus from the air and in air ducts in ventilation systems, transmission between cages of animals connected by air ducts, the high rate of asymptomatic transmission (i.e., passing on the virus when not coughing or sneezing), and transmission in quarantine hotels when individuals in different rooms shared corridor air but did not meet or touch any common surface.
The sentence after the one you emphasized seems to be saying what I was: the virus is in aerosol particles or potentially droplets, which are what your mask protects you from.
I recommend giving this a read when you have the time, it should hopefully answer any questions you have and better than I can.
An assumed droplet and contact mode of transmission leads to prevention policies that center on handwashing and surface cleansing, maintaining 2-m physical distancing, wearing medical masks (whose waterproof backing is designed to stop droplets) within that 2-m distance (especially when attending an infected patient), using physical barriers (e.g., plastic screens) and providing health-care workers with higher-grade respiratory protection only when undertaking AGMPs. However, if the virus is transmitted significantly by the airborne route, different prevention policies are needed, oriented to controlling air quality in indoor spaces (e.g., ventilation and filtration), reducing indoor crowding and time spent indoors, wearing masks whenever indoors, careful attention to mask quality (to maximize filtration) and fit (to avoid air passing through gaps), taking particular care during indoor activities that generate aerosols (e.g., speaking, singing, coughing, and exercising), and providing respirator-grade facial protection to all staff who work directly with patients (not just those doing AGMPs)
This is why I specified N95 respirators in my first comment. If you are unfamiliar, N95 is a NIOSH air filtration rating, which is used to describe the ability of a respirator to protect the wearer from airborne solid and liquid particulates. The review I linked goes into more details on this as well. I recommended N95 or better specifically because Covid is the illness I’m most concerned with avoiding, and the evidence suggests that they provide meaningful protection over lower grade respirators or surgical masks. Another quote from the link above that stood out to me:
The certification of surgical masks for particle/bacterial filtering efficiency (P/BFE) does not reflect equivalence to respirators as the filtration is typically compromised by poor face seal. The ASTM F2100-21 P/BFE certification, for example, requires at least 95% filtration against 0.1-µm particles and at least 98% against aerosolized Staphylococcus aureus, but this is on a sample of the mask clamped in a fixture, not on a representative face. In terms of filtering aerosols, N95 respirators outperform surgical masks between 8- and 12-fold. The effectiveness of certified surgical mask material against transmission when used as a filter was demonstrated in a hamster SARS-CoV-2 model. Infected hamsters were separated from non-infected ones by a partition made of surgical mask material; when the partition was in place, transmission of SARS-CoV-2 was reduced by 75%.
In addition to protecting the wearer, respirators provide very effective source control by dramatically limiting the amount of respiratory aerosols emitted by infectious individuals. In one study, risk of infection was reduced approximately 74-fold when infected, and susceptible individuals both wore well-fitting FFP respirators compared to when both wore surgical masks.
As for one-way masking, well, it is unfortunately significantly less effective (from what I understand), and is a big part of why I’m so concerned by others not masking. I simply cannot avoid being around others all the time, and their lack of effort is directly endangering me and my wife. If it really all came down to personal choice, I wouldn’t care if people wanted to risk their health. Still, while I don’t have any studies or anything to link you at the moment specifically on the effectiveness of one-way masking, all I know is that I mask and don’t get sick, and they don’t mask and do get sick. It’s anecdotal, sure, and I’m certain the mask is not the only thing affecting this, but as far as I can see it’s the largest difference in our behavior. I’ve heard as well that wearing a respirator will reduce viral load should you be infected despite the filter, and so your sickness will be less severe, but I don’t have any evidence on hand for this.
I thought masks wouldn’t protect against a virus (being tiny) but might help slow the spread to others by stopping spittle/moisture filled with virus from covering real world objects.
How do they help you if no one else is wearing them?
Because the virus is transmitted via spittle/moisture from other people not wearing masks. The virus doesn’t just hang out in the air on its own; it’s suspended in aerosol particles.
This is somewhat misleading. Here’s a section from near the beginning of a scientific review I linked in my reply to @[email protected]:
The sentence after the one you emphasized seems to be saying what I was: the virus is in aerosol particles or potentially droplets, which are what your mask protects you from.
Masks and respirators for prevention of respiratory infections: a state of the science review
I recommend giving this a read when you have the time, it should hopefully answer any questions you have and better than I can.
This is why I specified N95 respirators in my first comment. If you are unfamiliar, N95 is a NIOSH air filtration rating, which is used to describe the ability of a respirator to protect the wearer from airborne solid and liquid particulates. The review I linked goes into more details on this as well. I recommended N95 or better specifically because Covid is the illness I’m most concerned with avoiding, and the evidence suggests that they provide meaningful protection over lower grade respirators or surgical masks. Another quote from the link above that stood out to me:
As for one-way masking, well, it is unfortunately significantly less effective (from what I understand), and is a big part of why I’m so concerned by others not masking. I simply cannot avoid being around others all the time, and their lack of effort is directly endangering me and my wife. If it really all came down to personal choice, I wouldn’t care if people wanted to risk their health. Still, while I don’t have any studies or anything to link you at the moment specifically on the effectiveness of one-way masking, all I know is that I mask and don’t get sick, and they don’t mask and do get sick. It’s anecdotal, sure, and I’m certain the mask is not the only thing affecting this, but as far as I can see it’s the largest difference in our behavior. I’ve heard as well that wearing a respirator will reduce viral load should you be infected despite the filter, and so your sickness will be less severe, but I don’t have any evidence on hand for this.