Characteristics and key differences between different types of masks

N95 respirators are single-use devices, which are critical to prevent airborne infections in health care professionals (HCP), but shortages may occur during disease outbreaks. Hence, alternatives should be looked upon to mitigate these crisis situations.

Alternatives to Single-Use N95 Respirators

• Surgical masks were found to be equally efficacious as N95 masks in a hospital setting if they were worn regularly, with adherence to proper standards of wearing and removing them, and coupled with adequate hand hygiene measures.[13] MOHFW[14] has also advocated the use of surgical masks (a 3 layered mask which is disposable and fluid-resistant) by

  • Health care workers

  • If a person develops cough or fever

  • During a visit to a healthcare facility.

  • When you have to care for an ill person

  • Close family contacts of a suspect or a confirmed case/s undergoing home care.

• N95 – equivalent devices: Respirators not approved by NIOSH, but manufactured under regulatory standards, and in performance are equivalent to N95 masks, e.g., FP2 (Europe), KPN95 (China), or P2 (Australia)

• Reusable N95s and other respirators: Self-contained breathing apparatuses, elastomeric full-face N95s and N100s

• Expired N95 stocks: If stored properly, devices beyond their labeled shelf life usually retain adequate filter performance[15]

• N95s not certified for medical use: These include respirators certified by NIOSH but not certified by the Food and Drug Administration (FDA) (e.g., those for industrial use) and face covers made from conventional cloth or material used to make N95 filters.

Reuse or Extended Use of N95 Masks

Wearing an N95 respirator for hours at a time (i.e., extended wear) and reusing a respirator (i.e., donning and doffing between uses) are practices which can be adopted to ease shortages. With airflow rates consistent with breathing, theoretically, N95 protection should provide effective protection for prolonged hours, as long as the seal between respirator and face remains tight.

NIOSH and CDC guidelines do not include recommendations for reuse of single-use N95 respirators. Ideally, only the manufacturer of the respirators can provide reliable guidance on how to decontaminate their product. 3M, a manufacturer of N95 masks, also does not recommend the use of the following:[16],[17]

• Ethylene oxide (associated with release of volatile organic compounds)

• Ionizing radiation (damages the performance of filters)

• High temperature in microwave (melts the metal components resulting in compromise of fit).

Several methods for single-use N95 disinfection have been recommended by third parties:[12],[16]

1. Steam although nontoxic and easily penetrable to porous materials such as N95 filters, may damage polymer fibers in the filter and affect its performance

2. Chemicals could be toxic and incompatible with filter materials

3. Ultraviolet germicidal irradiation (UVGI) may not penetrate multilayered N95 masks, require enclosed space or shielded devices to protect users from ultraviolet (UV) exposure. UV equipment is equally expensive.

Although UVGI, hydrogen peroxide vapors, and moist heat have been most promising, their efficacy needs to be tested against different mask models.

Either reuse or extended use, both methods are associated with risk of mask to hand contamination, which can be decreased by:

• Covering N95s with surgical masks or use of face shield to reduce surface contamination

• Avoid touching the inside or outside of the mask while using it

• Hand hygiene before putting the mask and after removing

• Discard respirators when visibly contaminated with potential pathogen sources like body fluids

• Store used N95s in designated areas between reuses. It should be stored in a designated area, located indoors where they cannot become crushed or distorted, in their original packaging or in a breathable container such as a paper bag, in a hazard-free environment (clean air) which is away from direct sunlight and acceptable humidity and temperature.[18]

Any guideline that you adopt should be on the basis of local scenario and the materials available. If given a choice, extended use of N95 masks is preferred over its reuse:[12],[16],[19]

• The mask to hand contamination risk from N95s is higher by repeated contact (frequent donning and doffing) as compared to by aerosol (spread by breathing through a used mask)

• Use of a surgical mask or a face shield over an N95s during extended use provides extra protection from body fluids

• Decontaminated masks can be worn for patient care activities but not while performing a procedure which generates aerosols[12]

• Mechanical problems like broken straps or poor sealing between the mask and the user's face appeared immediately after a few uses even in FDA-cleared N95 masks

• Adequate disinfection vs. loss of filter performance although encouraging; is still an understudy.

When Left With No Alternatives, the Following Options May Also Be Considered

• Exclude high-risk HCP (old age, pregnancy) from COVID-19 from contact with known or suspected COVID-19 patients

• Convalescent HCP, i.e., Who have recovered from COVID-19 infection may be designated to take care of COVID-19 patients (but this has not yet been confirmed)

• Use only a face shield that covers the entire front, extends to the chin or below and covers the sides of the face

• In a poor resource setting, plan out a make shift isolation room (with the use of exhaust vents and high-speed table fans that provides a high-ventilation-rate and a zone under negative pressure.

Conflict of Interest

There are no conflicts of interest.

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Address for correspondence

Publication History

Received: 17 April 2020

Accepted: 17 July 2020

Article published online:
17 May 2021

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