DR. POOJA K. DIGRA & DR. KISHOR K. DIGRAA medical face mask also known as surgical or procedure mask is a medical device covering the mouth, nose and chin ensuring a barrier that limits the transition of an infective agent between the hospital staff and the patient. They are used by healthcare workers to prevent large respiratory droplets and splashes from reaching the mouth and the nose of the wearer and help reduce and/or control at the source the spread of large respiratory droplets from the person wearing the face mask. That aim to balance high filtration, adequate breathability and optionally, fluid penetration resistance.Non-medical face masks (or ‘community’ masks) include various forms of self-made or commercial masks or face covers made of cloth, other textiles or other materials such as paper. They are not standardised and are not intended for use in healthcare settings or by healthcare professionals.A respirator or filtering face piece (FFP), is designed to protect the wearer from exposure to airborne contaminants (e.g. from inhaling infectious agents associated with inhaling small and large particle droplets) and is classified as personal protective equipment (PPE). Respirators are mainly used by healthcare workers to protect themselves, especially during aerosol-generating procedures. Valved respirators are not appropriate for use as a means of source control since they do not prevent the release of exhaled respiratory particles from the wearer into the environment. Filtering facepiece respirators (FFR), or respirators, similarly offer a balance of filtration and breathability; however, whereas medical masks filter 3 micrometre droplets, respirators must filter more challenging 0.075 micrometre solid particles. Certified FFRs must also ensure unhindered breathing with maximum resistances during inhalation and exhalation. Another important difference is the way filtration is tested; medical mask filtration tests are performed on a crosssection of the masks whereas FFRs are tested for filtration across the entire surface. Therefore, the layers of the filtration material and the FFR shape, ensuring outer edges of the FFR seal around wearer’s face, result in a guaranteed claimed filtration when worn compared to the open shape, or leaking structure, of medical masks. Other FFR performance requirements include being within specified parameters for maximum CO2 build up, total inward leakage and tensile strength of straps.Why N95 respirator not to wear by general public The use of medical masks in the community may divert this critical resource from the health workers and others who need them the most. In settings where medical masks are in short supply, medical masks should be reserved for health workers and at-risk individuals when indicated. Avoid wearing a mask which has valves or openings on the front as it might be a ‘one-way valve’ which only going to protect the person who is wearing it. Mask with a one-way valve does not filter aerosols coming out of your mouth, hence, immediately putting those around you at risk. The idea of an effective face mask to prevent you from catching a respiratory illness is that it protects others too. A mask which will protect you but put those around you at risk cannot help in containing COVID-19. An N95 respirator that has a two-way valve is capable of filtering out particles during both inhaling and exhaling, however, these are mostly used by health professionals given the extent of their exposure to virus droplets. Valved N95 respirator “does not prevent the virus from escaping out of the mask….” and refers to government’s advisory issued in April on the use of ‘homemade protective cover for face and mouth’, particularly when they step out of their residences.Procedure for wearing a maskAs per the Indian Council of Medical Research (ICMR), you must wash your hands with soap and water for at least 20 minutes before wearing a mask. In case you do have access to soap, you can use alcohol-based sanitizer. To take it off, firstly clean your hands with sanitizer and then remove it. Wash your hands post disposing of too. Notably, you must change your mask every 8 hours and avoid wearing a wet mask. Never share your face mask with anyone even if you are sure the person is COVID-19 negative.The different ways of sterilizing and reusing the maskThe advisory says that any used cotton cloth can be cut out into a face cover, stressing that such cloth-based homemade masks must be washed and cleaned each day. The colour of the fabric does not matter but one must ensure that the fabric is washed well in boiling water for five minutes and dried well before making the face cover. Adding salt to this water is recommended, as per the government advisory. Ensure your face mask fits properly and covers your nose, mouth and chin. Do not touch your mask while you are wearing it. The sterilizing and reusing the N95 mask are as follows –o Air drying: This is a simple way of reusing the N95 respirator mask. Drying the mask kills the virus, but it takes at least 48 hours to dry. Therefore, drying in a clean, dry place for 72 hours (3 days) is one way of reusing the mask. The only issue is that you have to wait for 3 days to reuse it. If you have four N95 masks, wear one every day and then keep it for drying, until the fourth when it can be reused. Keep the mask in a paper bag away from direct sunlight and ultraviolet rays. If in the meantime, the mask becomes soiled, damaged or difficult to breath, you need to discard it. Needless to say, always practice hand hygiene before removing and wearing it again the next time.Heat in an oven: Heating at 70 degrees C for 30 mins kills the virus. There should be no contacting metal, and check if the N95 material used is not inflammable, if it is, do not heat in oven. You can hang the mask in the oven by using a wooden clip. This work has been done by the Stanford University team, USA and up dated on 25th March 2020.Dry heat in a rice cooker: Put the N95 mask in a traditional electric rice cooker without putting any water inside for 3 mins, until the temp is 149 -164 degrees C.Chemical sterilization with H2O2: Researchers from Duke University in the USA reported that using H2O2 (480 ppm) in a specially designed chamber for 45 mins sterilizes the filter without destroying it. It takes a total duration of 4 hrs. The paper describing the method has been accepted in the Journal of Applied Biosafety as on 26th March 2020.15 At around the same time (27th March 2020), researchers from the Yale University, USA too have reported effective disinfection of the N95 mask with H2O2.
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