To wear a mask, or not to wear a mask, that is the question. There is conflicting information daily as to the need or usefulness of masks for use by those without symptoms. After reading a commentary on the website Medscape (which is for physicians) then another commentary from the University of Minnesota Center for Infectious Disease Research and Policy, I thought I would give you a synopsis so you can make your own decision. Unless of course it becomes a government mandate.
Medcape Orthopedics, April 1, 2020, Ann L. Baxter,MD Is it Time That We All Start Wearing Masks?
Dr. Baxter stated that countries such as Japan, China and South Korea that have had a flatter curve of infection or are on the other side of the curve have strict government mandates on mask usage. She pointed out that the Czech Republic which has had 24 deaths and 3002 cases as of 3-31-20 not only has a mask mandate but a fine of $800USD for public disobedience.
She stated that Hong Kong has mandated school closures, and Singapore has strict quarantine and contact tracing and both have flattened curves. While Japan which has also slowed growth, has only light testing and isolating but they all have adopted mask wearing.
She feels that mask wearing has been discouraged by US healthcare professionals and the World Health Organization in an attempt to reserve N95 respirators for health care workers. She said that respiratory droplets have diameters in the range of 10-100µm and that a study looking at cloth masks found a filtering efficiency of 63-84% for the small droplets. (I looked at this study and they pointed out that the filtering efficiency dropped 20% after the fourth washing and drying). Her conclusion was that while they are not stopping all of the droplets they are stopping the bigger ones better than nothing, and felt that they should be universally worn.
University of Minnesota Center for Infectious Disease Research and Policy, April 1, 2020, Lisa M Brosseau, ScD and Margaret Sietsema, PhD Commentary: Masks-for-all for COVID-19 not based on sound data
They do not recommend requiring the general public who do not have symptoms of COVID-19 like illness to routinely wear cloth or surgical masks because:
•This is no scientific evidence that they are effective in reducing the risk of SARS-CoV-2
•Their use may result in those wearing the masks to relax other distancing efforts because they have a sense of protection
•We need to preserve the supply of surgical masks for at-risk healthcare workers.
They pointed out that widespread mask use was in place in Hubei province China before and after the mass COVID-19 transmission experience. Also noted was a study showing that surgical masks can help decrease the dispersal of particles when worn by someone that is sick.
They referred to a study done by The National Institute for Occupational Safety and Health (NIOSH) that evaluated the filter performance of different materials and masks. They used particle sizes ranging from .02 to 1 µm(which is much smaller than the above study). The N95 mask had greater than 95% efficiency, T-shirts had 10% efficiency, scarves 10-20%, cloth masks 10-30%, sweatshirts 20-40%, and towels 40%. They referred to several other papers to support their position.
Now that I have completely confused you, let me try to summarize. N95 masks have an electrostatic charge along with smaller pores to have superior filtration which is why healthcare workers need them. They are going to be exposed to a much higher viral load (number of viruses) than most of us going to the supermarket. Cloth masks will catch larger particles when worn by someone with symptoms. The concern is those with a cloth mask will not practice social distancing as stringently as they would without a mask and thus become infected.
I found a paper at the National Institute of Health titled Natural Ventilation in Health Care Settings for Infection Control which said droplets ≥5µm will fall to the ground but those ≤5µm can stay suspended in the air. That means the cloth mask will not filter or catch the airborne droplets. In the 2007 Journal of Aerosol Medicine a paper looking at the size and speed of particles in a sneeze put the size range of particles .58-5.42µm.
Since asymptomatic people can be infected and spread the virus a cloth mask is really to protect others from you rather than you from others. I hope this helps.