BY DR. LAWRENCE W. GERNON
PROFESSOR OF GLOBAL HEALTH, GLOBAL NATIONAL SECURITY & POLICY INSTITUTE, UNM
Irrational decisions formulated around speculation without a basic understanding of science and physics is kindling for a forest fire in the times of contagion. While individuals have every right to wake up in the morning and choose their attire, there are businesses now requiring employees and customers to wear a mask — cloth or dust/surgical. If you are wearing a mask as personal protection equipment (PPE) and not solely for your wardrobe attire, then we must address some basic questions: 1. Will a mask protect me from a viral infection?
2. Will a mask protect others from contracting a droplet/ airborne viral infection from me if I am not coughing or sneezing?
3. Is there a difference in protection with either mask?
Size makes a difference, and viruses generally are much smaller than bacteria and range in size from 0.01 micron to 0.3 micron. The SARS CoV-2 virus responsible for COVID-19 infection is 0.1 micron. Your body’s natural defense respiratory system is able to efficiently filter and remove foreign substances over 2.5 microns. Those particles managing to breach the mucociliary clearance and to penetrate deeply now face the special forces of the nonspecific and specific immune system, who have maintained vigilance since birth.
A study published in 2010 under the auspices of National Institute for Occupational Safety and Health found many fabric materials including shirt, sheet, towel and handkerchief to be ineffective against viruses, with the effectiveness factor diminishing with decreasing particle size from 4.8 microns to 0.41 microns, indicating further decrease in the respiratory protection for viruscontaining particles (smaller than) 0.41 microns. The use of fabric materials is unlikely to have respiratory protection to a wearer against virus-size submicron aerosol particles.
A randomized trial comparing the effect of medical and cloth masks on health care worker illness found that those wearing cloth masks were 13 times more likely to experience influenza-like illness than those wearing medical masks.
In sum, very poor filter and fit performance of cloth masks and very low effectiveness for cloth masks in health care settings led us to conclude that cloth masks offer no protection for health care workers inhaling infectious particles near an infected or confirmed patient.
The CDC has published conflicting data on protection implied by cloth masks and/or surgical masks. Suffice it to say, the concern centers on a shortage of N-95 respirators and surgical masks during a pandemic, ensuring adequate supplies are available for health care workers on the frontline of this pandemic who require personal protection equipment.
The only time a cloth mask may be marginally effective is when the user is coughing or sneezing. On the contrary it provides the wearer little protection from microorganisms expelled from others who are infected with respiratory diseases.
Surgical/procedure masks are intended to help put a barrier between the wearer and the work environment or sterile field. They may help keep saliva and mucous generated by the wearer from reaching a patient or medical equipment. They can also be used as a fluid barrier to help keep blood splatter from reaching the wearer’s mouth and nose. They are not respirators and do not offer any respiratory protection for particles less than 100 microns and are only intended for splash protection.
One of the only randomized controlled studies done comparing cloth masks with surgical masks in health care workers reiterated the findings from previous studies, confirming higher rates of respiratory illness, influenza like illness and laboratory confirmed viral illness with those using a cloth mask vs. surgical mask. Penetration of cloth masks by particles was almost 97% vs. medical masks 44%, and moisture retention may result in increased risk of infection.
In conclusion, while wearing a mask is an individual’s choice, understanding the level of protection and transmission is key. These masks offer no additional protection to the common-sense public health measures of social distancing, and, most importantly, frequent hand washing.
Dr. Lawrence W. Gernon is an attending physician at the Raymond G. Murphy Medical Center, Department of Emergency Medicine.