zonefive:
I have to respectfully disagree with you claim. From what I have read, I think there is enough evidence to say that during this virus pandemic, the best benefit of wearing a face mask is for people who have COVID-19 or any other virus, such as influenza, to prevent them from giving COVID-19 to other people. The secondary benefit is preventing their inhaling virus particles. Let’s not forget that over the past year, epidemiologists learned how the COVID-19 virus was spreading via airborne transmission, emitted in high quantities from a person’s upper respiratory tract. The CDC report you reference, dated May 2020, was published before this fact was finally established. Therefore, universal face mask wearing, when outside your home and around other people, is the best tool to limit, but not eliminate the possibility of its transmission.
Masks are probably more effective as a “source control” because they can prevent larger expelled droplets from evaporating into smaller droplets that can travel farther. The concept of wearing a face mask is risk reduction rather than absolute prevention, recognizing that no mask will be 100% effective. A good analogy is that people with high cholesterol do not take a statin medicine because they are going to prevent a heart attack 100% of the time, but because they are reducing their risk of having a heart attack substantially.
The level of effectiveness of a face mask really depends on its design, material and proper fit to prevent particle transmission and air leakage. Realistically, for all practical purposes for the general public and wearing face masks, there is a trade-off and compromise between comfort and effectiveness. It is understandable that health care workers use N95 respirators in medical situations such as intubation, as well as when around COVID-19 patients. The Chinese version of the N5 respirator is the KN95 face mask, that is now available for the general public to purchase online, (I got mine via Amazon). Surgical masks are generally more protective than cloth masks, and some people find them lighter and more comfortable to wear. The bottom line is that any mask that covers the nose and mouth will be of benefit.
A recent study published in Health Affairs, for example, compared the COVID-19 growth rate before and after mask mandates in 15 states and the District of Columbia. It found that mask mandates led to a slowdown in daily COVID-19 growth rate, which became more apparent over time. The first five days after a mandate, the daily growth rate slowed by 0.9% compared to the five days prior to the mandate; at three weeks, the daily growth rate had slowed by 2%
Are face masks the holy grail in this effort to stop the spread of COVID-19? No they are not, but they are pretty effective. Another factor to remember is that you could still catch the virus through the membranes in your eyes, a risk that masking does not eliminate and why plastic face shields make sense for some people, such as Dental Hygienists, etc..
Don’t take my word for it. FYI - here are links to several articles and research papers by people who have been studying this issue and the results they have come up with.
https://www.skeptic.com/reading_room...RoCq4MQAvD_BwE
http://files.fast.ai/papers/masks_lit_review.pdf
https://www.medrxiv.org/content/10.1...567v2.full.pdf