IRSST - Institut de recherche Robert-Sauvé en santé et en sécurité du travail

IRSST's Notices, Recommendations and Support Tools

The contribution of occupational health and safety (OHS) research to the fight against the COVID-19 pandemic.

Reusable elastomeric respiratory protection equipment (RPE) (full masks and half masks) are useful alternatives for the protection of workers during the COVID-19 pandemic. When used appropriately, RPE can give workers protection factors equivalent to or greater than those of disposable N-95 filtering facepieces. They could also be valuable in the event of a potential shortage of N-95 masks. An independent working group considers the routine use of reusable elastomeric RPE in health care institutions to be a viable option when a respiratory protection program is in place[1].

The Practical respiratory protection guide[2]describes different kinds of equipment and how to use them. One of the keys to safe use of reusable RPE for respiratory protection against the SARS-CoV-2 coronavirus is implementing an RPE maintenance, cleaning and storage program. As described in the Guide, the program should include the following points:

  • cleaning and disinfection of RPE;
  • inspection, testing and repair of RPE;
  • storage;
  • recordkeeping.

Section 6.1 of the Practical respiratory protection guide specifically covers cleaning of RPE. This equipment should be cleaned and disinfected regularly, according to an established procedure or the manufacturer’s recommendations.

The procedure recommended in the Practical respiratory protection guide, which is inspired by the one formulated by OSHA [3], has been modified to take account of the danger from the SARS-CoV-2 coronavirus. The procedure is also inspired by those presented by Lawrence et al. (2017) [4], Bessesen et al. (2015)[5], the US Centers for Disease Control and Prevention (CDC) Guideline for Disinfection and Sterilization in Healthcare Facilities[6]and 3M’s technical notes regarding key procedures and factors for RPE cleaning and disinfection in relation to COVID-19 [7][8].

The procedures for inspection, donning, facepiece sealing tests and doffing must always be respected and must comply with your institution’s guidelines.

The modified cleaning and disinfection procedure is presented below.

Procedure for cleaning reusable elastomeric respiratory protection equipment in the context of COVID-19

Doff the RPE in the clean zone with clean gloves.

  • Remove the P100 filters (or other particle filters) from the RPE and set them aside on a disposable alcohol wipe.
  • Wash the RPE by immersing it in lukewarm water (maximum 43 °C) with a gentle detergent or any cleanser recommended by the manufacturer. Rub with a soft brush for 1 minute. Do not use cleansers containing lanolin or other oils and do not use a brush with metal bristles.
  • Rinse the parts in lukewarm running water.
  • The RPE must then be immersed for a minimum of 1 minute in a solution of sodium hypochlorite (5,000 ppm, see box) to be disinfected. Place the RPE facedown to avoid the formation of air bubbles in the mask. Swish it around to remove any residual bubbles.
    The hypochlorite solution (approximately 5,000 ppm of available chlorine) can be made by adding 100 ml of bleach (5%) to 900 ml of lukewarm water. Since the concentration levels of commercial and industrial bleach vary, it is advisable to use the following calculator, developed in Ontario, to validate the necessary volumes to make your solution :
    Note: 1% is equivalent to 10,000 ppm.
  • Rinse the RPE firmly with lukewarm running water for a minimum of 2 minutes. Drain. It is important to rinse well, since soap and disinfectant that dry on parts of the RPE can irritate the skin and cause dermatitis. In addition, some can degrade the rubber or corrode the metal parts.
  • The RPE must be dried with a clean cloth, paper towel or simply air-dried in a clean location.
  • Keep it in a clean container that is not hermetically sealed to avoid retaining moisture.
  • Follow the procedure for inspecting and donning the RPE. Check its seal each time it is used.
    Note: Although bleach can cause premature wear of the elastics, the procedure does not recommend removing them to facilitate its application in case of a pandemic.

Factors to consider in relation to the selection and maintenance of particle filters for reusable elastomeric RPE

  • All classes of particle filters can be used.
  • Particle filters encased in a hard shell are very strongly recommended if the filters will be reused since a hard shell is easier to clean due to its smooth surfaces. Although reuse is not normally recommended for infectious agents, in case of a pandemic, this alternative is suggested to avoid shortages.
  • Since 3M indicates that it is not very likely that filters will clog due to an overload of particles in health care institutions, the decision on whether to replace filters must be based on considerations related to infection prevention. 3M notes that RPE is used to filter air contaminants and thus the contaminants will be concentrated on the filter itself. 3M provides some guidance on replacement frequency in its note on powered air purifying respirators [8], but it leaves the final decision up to the user in the case of reuse to protect workers against SARS-CoV-2.

Procedure for cleaning the hard shells of particle filters for reusable elastomeric masks

  1. Take the particle filters (shells) that were placed on the moistened wipe while you were cleaning the half mask.
  2. Gently rub the outside surfaces of the shell with a rag or wipe soaked in disinfectant (see NOTE below). Choose a disinfectant from the list of products the EPA recommends as being effective against SARS-CoV-2. Always make sure that the contact time is respected (e.g., for sodium hypochlorite with 5,000 ppm of available chlorine, the contact time must be at least one minute; consequently, the surface must remain wet while the filter is rubbed for one minute).
  3. Rinse with a clean cloth soaked in water, rubbing gently.
Be careful not to let liquids contact the filtering medium inside the shell, since that could affect the efficacy of filtration.
  1. Dry with a clean cloth or simply air-dry in a clean location.
  2. Keep in a (new, clean, well-maintained) non-hermetically sealed container separately from the RPE.

NOTE: Tests done at the IRSST on P100 7093 filters from 3M have shown that 20 successive cleanings with sodium hypochlorite 5,000 ppm did not change their filtration performance or seal (tested with quantitative fit testing).

Always be sure to check the seal carefully. In case of doubt or difficulties maintaining negative pressure during the test, throw out the particle filters and take new ones.

CAUTION: The use of denatured alcohol (ethanol + methanol) is not advisable because it appears to damage the plastic of the shells and thus the ability to test the seal by negative pressure. Commercial wipes already moistened with disinfectant can make the filter unusable due to a strong residual odour. Too much fragrance is given off in the mask.

[1]National Academies of Sciences, Engineering, and Medicine. (2019). Reusable elastomeric respirators in health care: Considerations for routine and surge use. Washington, DC: The National Academies Press.

[2]Lara, J., & Vennes, M. (2002). Guide pratique de protection respiratoire (2nd ed.). Montreal, QC: Commission de la santé et sécurité du travail and Institut de recherche Robert-Sauvé en santé et en sécurité du travail.

[3]Occupational Safety and Health Administration. (n.d.) OSHA technical manual, Section VIII: Chapter 2, Respiratory protection.

[4]Lawrence, C., Harnish, D. A., Sandoval-Powers, M., Mills, D., Bergman, M., & Heimbuch, B. K. (2017). Assessment of half-mask elastomeric respirator and powered air-purifying respirator reprocessing for an influenza pandemic. American Journal of Infection Control, 45(12), 1324–1330.

[5]Bessesen, M. T., Adams, J. C., Radonovich, L., & Anderson, J. (2015). Disinfection of reusable elastomeric respirators by health care workers: A feasibility study and development of standard operating procedures. American Journal of Infection Control, 43(6), 629–634.

[6]Rutala, W. A., Weber, D. J., & the Healthcare Infection Control Practices Advisory Committee. (2008). Guideline for disinfection and sterilization in healthcare facilities (updated 2009).

[7]3M. (2020). Personal safety division cleaning and disinfecting 3M reusable elastomeric half and full facepiece respirators following potential exposure to coronaviruses.

This notice has been prepared by the IRSST, in collaboration with its social partners, employer and worker representatives, and members of its Scientific Advisory Board.