Can N95 (FFP2) masks be reused after disinfection? And for how many times?

• Publication: Stanford University School of Medicine (California)
• The COVID-19 pandemic has led to a major shortage of N95 face masks equivalent to FFP2 masks, particularly among healthcare professionals.
• The Stanford team studied three promising disinfection methods that can be applied to the recycling and reuse of face masks :
  • Hot air (75°C, 30 min).
  • UV light (254 nm, 8 W, 30 min).
  • Water vapor (10 min).

They determined the following :

• Hot air applied over 20 cycles did not degrade filtration with efficiency (> 95%). It can be implemented using an oven, an autoclave, a warming cabinet, etc.
• The UV treatment over 10 cycles did not degrade the filtration efficiency with an efficiency (> 95%).
• Steam treatment requires caution, because the filtration efficiency can be maintained (>95%) in 3 cycles, but the efficiency will degrade to ~85% after 5 cycles, and finally drops to ~80% after 10 cycles.
• With regard to hot air (75 ° C, 30 min, 20 cycles), They found that an N95 mask did not undergo any mechanical deformation, The fastening loops at the ears were retained with good elasticity required for use.
• Furthermore, the Stanford researchers point out that “no caregiver should bring contaminated material home at the risk of infecting their loved ones” and that recycling of masks should never be carried out at home.

Refrence :

Liao L, Xiao W, Yu X et al. Can N95 facial masks be used after disinfection? And for how many times? Report from the collaboration of Stanford University and 4C Air, Inc., March 25, 2020

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