When Covid first appeared on the scene last February, there was much debate whether wearing a face mask would be helpful. The opinions of many medical experts were even ambiguous at first, but soon enough became clear that reducing or eliminating Covid aerosol droplets from the air would reduce... perhaps prevent...the transmission of respiratory based viral infections.
Recent social media and news discourse on wearing multi-layered masks has conjured mixed opinions by the public and medical experts. After all, if one mask is good enough, isn't 2...maybe 3 better yet? Let's see.
N95 MASKS: The most effective kind of face mask besides HazMat style respirators used in chem labs, are the N95 masks. When properly worn, these masks can effectively block 95% or more aerosol droplets that are microscopic (.3 micrometers) that could be infected with the Coronavirus. Why? Because N95 masks are composed of compressed, non-woven, layered material that resists penetration by microscopic particles smaller than .3 micrometers.
SURGICAL STYLE MASKS: These are the standard, usually blue in color mask that is now readily available in most retail stores, gas stations, and street vendors. Typically composed of 3 layers of material, these can be worn in casual settings where people are in close proximity of one another, in what the CDC considers to be the level of exposure consisting of 15 minutes (cumulative exposure) with someone < 6 feet apart.
BANDANAS, NECK GAITERS, VALVED MASKS Woven fabric is the primary material that makes up bandanas and neck gaiters. These can slow down respiratory droplets, but not prevent the exit of enough aerosols to be meaningful in certain scenarios. Valved masks are no better in that exhaled respiratory droplets leave the valve unchecked and free to linger in confined air spaces...not a great plan when you are trying to protect others. The masks in this category are typically effective in reducing or blocking dust, dirt, and large particles, but not microscopic particles.
MULTI-LAYERING By using a combination of cloth and a surgical mask, or 2 surgical masks increases the number of barriers that a respiratory particle has to penetrate in order to leave your face or enter your nasal passages from the outside. When worn in a slightly staggered overlap, surgical masks can provide a better seal and significantly reduce particle entry into the respiratory tract more so than an individual mask would. But there are some down sides.
Increasing layers of masking, whether cloth or surgical mask, or surgical mask + N95, effectively increases air resistance which means it is harder to breathe in OR out. Thicker layers also increases humidity inside the mask, increasing the level of air resistance with subsequent or prolonged use. Those with respiratory disorders like COPD, asthma, allergies, and even mild sinus infections can find it challenging to wear more than 1 mask during the day.
WHEN SHOULD YOU WEAR MULTI-LAYERS If you are not one with respiratory issues, you might benefit from multi-masking when you expect to be in high concentrations of people for prolonged exposure times. Elevators, close gatherings, inside cars and buses, airlines- these are likely good scenarios to double up. Don't plan on exerting physically while wearing multilayers because you'll find it difficult to breathe properly.
BOTTOM LINE...
Multilayering masks can have it's benefits when worn in specific scenarios. Prolonged use can accumulate air resistance and humidity that would produce diminishing returns after a while, so use multilayering with caution!
Dr. Adrian has been in private practice for over 20 years, is a lecturer, and works in various professional extreme sports events throughout the year with Red Bull. He is an advocate of Strength Training, Conditioning, and athletic performance by nutritional and training hacks. You can reach him at southpaschiro@gmail.com