COVID-19 Prevention by N95 Facial Masks: Filtration Efficiency, Effectiveness, and Availability

The N95 masks were the most affected by the shortage. The N95 respirators are known for filtering 95% of small 0.3-mm particles. They are the most important protection against airborne pathogens.

There is reason to be optimistic about their effectiveness in real life, despite the low filtration efficiency of non-NIOSH-approved surgical masks. Even though surgical masks are less effective than N95 mask in terms of filtration efficiency, there is reason to believe that they work in real-world settings. It is important to note that no SARS-CoV-2 cases have been reported in settings where surgical masks were used instead of N95 respirators. This suggests that surgical masks may be sufficient to block most of the virus particles in most cases.

The effectiveness of any mask depends heavily on its actual-world use. Mask filtration may vary more due to mask fit and adherence than marginal differences in laboratory-based efficiency. Practically, N95 masks can be uncomfortable and suffocating if worn correctly. For N95 use, it is important to do periodic, individual fit testing and to check that the mask has been sealed properly before wearing. The fit of a mask varies according to facial shape and body habits. It is important that you ensure the exact same size and manufacturer as your fit test. Even small amounts of facial hair can compromise the mask’s filtering efficiency. Masks that are too tight can cause facial bruising or abrasions. However, bandages placed over these areas (e.g., the common wound barriers above the nasal bridge) will not allow the mask to seal. Although a recent clinical trial reported similar and suboptimal self-reported adherence between outpatient health care personnel randomized to wear N95 masks Vs medical masks (89% Vs 90%), the study also demonstrated no difference in cases of laboratory-documented influenza–albeit a different respiratory virus–between the 2 groups. Recognizing that mask effectiveness in the laboratory is higher during the COVID-19 pandemic and that clinical settings are more effective, it’s likely that the lab results reflect a lower limit of effectiveness.

The N95 laboratory-based efficacy of N95 masks and the need to ensure proper fit-tested usage have made it difficult to procure adequate supplies. KN95 masks can’t be purchased in the United States. They were, however, sold at $2-$4 per mask during times of crisis. It is best to dispose of any expired masks that you don’t want. Although competition and price gouging have certainly hampered access to masks, the main problem has been supply. Reprocessed Masks are the best solution to this problem. These masks may cost as much as six times their original cost. Until we have a better understanding of how filtration efficacy translates to improved protection against SARS-CoV-2 transmission, health care systems are left to pay top dollar to keep their most valuable resources–clinicians and health care workers–safe.

Pandemic preparedness is crucial to avoid future shortages of PPE due to supply chain disruptions and rising costs. It is crucial that the health care sector continues to innovate to address PPE shortages. We must ensure that supply and demand are in balance when there is severe shortage. Essential health care workers and frontline doctors who are involved in high-risk procedures should have the best protection. NIOSH-approved N95 respirators should be available. They offer a safer alternative to N95 single-use masks. Even though they have lower filtration efficiency of submicron particles surgical masks and N95 alternatives may provide sufficient protection against transmission for routine care.