The characteristics and use of surgical masks

The document - edited by the Risk Assessment and Human Health Research Group of the Department of Science and High Technology (University of Insubria - Como) with the contribution of the National Board of Directors of the AIDII Association - indicates that wearing a surgical mask "is one of the preventive measures to limit the spread of some respiratory diseases ".

In particular, medical-surgical masks “are single-use smooth or pleated face masks (some have the shape of a cup), which are placed on the nose and mouth and fixed to the head with laces or rubber bands. These constitute a useful protective barrier in the spread of pathogens transmissible by air (aerosols and droplets). In relation to the filtration efficiency and respiratory resistance they can be of 4 types: I, IR, II and IIR. Those of type II (three layers) and IIR (four layers) offer greater bacterial filtration efficiency (≥ 98%), the IIR is also resistant to splashes (Medical Device Regulation (EU) 2017/745; EN 14683: 2019) ".

It is also recalled that, with regard to the COVID-19 emergency, the World Health Organization (WHO) recommends "wearing a medical-surgical mask when it is suspected that you have contracted a SARS-CoV-2 infection and / or when symptoms such as coughing or sneezing occur, or when it is necessary to come into contact with a person with suspected SARS-CoV-2 infection ”.

Furthermore "the use of the medical-surgical mask must be adopted in addition to other respiratory and hand hygiene measures , and all other precautionary measures to be taken in public places and in the home environment arranged in the context of the COVID emergency- 19 ". Furthermore, it is not “useful to wear several overlapping medical-surgical masks. Furthermore, the incorrect use of a mask can compromise its effectiveness in reducing the risk of transmission, just as it is not recommended to use a mask that is not suitable for the purpose. The medical-surgical mask, when necessary, must be worn, removed and disposed of correctly, following appropriate procedures "(the document contains a WHO link ). Finally, it is recommended to "replace the medical-surgical mask with a new clean mask at the end of the activity that may have involved exposure to SARS-CoV-2, or as soon as the one in use becomes moist".

Information on personal protective equipment

With regard to the protection of workers, it is "recommended as a matter of priority to strictly and scrupulously follow - even in the workplace - all the indications relating to behavior and general precautions to be taken in public places and in the home environment, arranged in the context of the COVID emergency. -19. Among these, also the use of surgical masks, in the foreseen cases (when it is suspected of having contracted the Coronavirus and / or symptoms such as coughing or sneezing, or when it is necessary to come into contact with a person with suspected SARS infection- CoV-2) ".

Furthermore, the use of real " Personal Protective Equipment (PPE) of the respiratory tract (FFP - according to the regulations) - in place of the use of medical-surgical masks - should be carefully evaluated in specific cases, with particular reference to all operators who may come into direct contact with people with respiratory symptoms, or with subjects with a suspected or confirmed diagnosis of COVID-19 , as well as with subjects placed in quarantine ".

It is recalled that more specific indications have been defined for healthcare professionals .

Healthcare professionals "must wear (in addition to other PPE such as disposable gowns, gloves and goggles) a medical-surgical mask when entering a room where patients with a suspected or confirmed diagnosis of SARS-CoV-2 infection are admitted and in any situation of care provided to a suspected or confirmed case. It is also recommended to use a protective mask for particulates with a class certified at least to FFP2, when performing procedures that generate aerosols (such as tracheal intubation, non-invasive ventilation, tracheostomy, cardiopulmonary resuscitation, manual ventilation before intubation and bronchoscopy) ".

Particulate protective masks are “personal protective devices for the respiratory tract typically used in workplaces or for professional uses. The European classification of types 1 (FFP1), 2 (FFP2) and 3 (FFP3) defines the level of protection of the operator against aerosols and droplets with a degree of efficiency of respectively 80%, 94% and 98%. The filtering facepieces are further classified as: “usable only for a single work shift” (indicated with the initials NR) or “reusable” for more than one work shift (indicated with the letter R). Devices compliant with current legislation (Regulation (EU) 425/2016) must be provided with the CE marking affixed in a legible, indelible manner for the entire duration of the PPE. PPE must comply with specific technical standards (UNI EN 149: 2003) in order to comply with the desired protection factor ".

It is also recalled that for their optimal effectiveness - and to "avoid misuse with consequent false security of being protected" - these " must be worn, removed and disposed of correctly, following appropriate procedures ". "In the event that respiratory protection is required for a workplace, moreover, the use of PPE must be included in the context of a more extensive and comprehensive program of prevention and protection, which should include the fit-test, medical evaluation and operator training / education ".

The document then focuses on the supply problems of these devices .

In fact, medical-sanitary masks and PPE for the respiratory tract “should be marked with the CE mark and comply with specific technical standards regarding their manufacture, design and performance and test methods. However, as defined by art. 34, paragraph 3, of Legislative Decree no. 9/2020 , ' in relation to the emergency referred to in this decree, in accordance with the guidelines of the World Health Organization and in accordance with current scientific evidence, it is allowed to use surgical masks, as a suitable device to protect the health workers; masks without the CE mark can also be used after evaluation by the Istituto Superiore di Sanità '".

Therefore - continues the AIDII document - “we consider it useful to remember that type P2 respiratory PPE can be considered to correspond to respirators classified as N95 and those of type P3 to those classified as N99 by US regulations”. The document contains a link with further information on the equivalence of other respiratory PPE classification systems. And indicates that "the equipment of masks that do not comply with CE certification and the technical standards cited in the text can only be considered in the context of an imminent shortage of medical-surgical masks and PPE for the respiratory tract compliant with these requirements, and in any case subject to the expression of a judgment of technical compliance ".

The use and management of masks and PPE for the respiratory tract

The document recommends the utmost attention in the use and management of medical-surgical masks and PPE for the respiratory tract, also to overcome any supply problems. In this sense, "various indications have been provided for the rational use of these resources in the workplace in general to meet the needs of masks and PPE in conditions of limited availability" (we refer to the reading of the document which contains numerous useful links for suitable strategies).

The document focuses in particular on three aspects:

1. " The use of PPE for the respiratory tract beyond the shelf life designated by the manufacturer (for training and fit tests): the use of PPE for the respiratory tract beyond the shelf life indicated by the manufacturer may be considered . However, please note that expired respirators may not meet the requirements for which they have been certified. The use of devices that have passed the indicated expiration date could be used primarily for activities such as worker training and fitness testing.
2. prolonged use of PPE for the respiratory tract : refers to the indication to wear the same device for repeated encounters / interventions / situations that may involve exposure with the pathogen, without removing the respirator between one event and another.
3. the 'limited reuse' of PPE : refers to the practice of using the same device for multiple meetings / interventions / situations that may involve exposure with the pathogen, but removing it after each event. The respirator must be properly stored to be put on again before the next encounter.

It should be noted that, "although these practices allow the potential advantage of allowing the reduction of consumption of such devices, concerns have been raised regarding the adoption of these practices, among which the most significant risk is the transmission of pathogens by contact with the surface. contaminated respirator . There are also restrictions that limit the number of times the same device can be reused ”.

In particular, “ prolonged use is preferable to reuse, since it implies less need to touch the PPE and consequently less risk of contact infection. A fundamental requirement for extensive use is that the PPE must maintain its characteristics and functionality unaltered. In any case, it is necessary to adequately inform and train personnel on the correct procedures for removing and reusing PPE and in particular with respect to the following points :

• it is necessary to dispose of the PPE after use for operations involving the generation of aerosols;
• PPE must be disposed of if it is visibly contaminated with blood, nasal or respiratory secretions or body fluids;
• it is necessary to dispose of the respirator if used with subjects with an established diagnosis of pathologies that involve the risk of transmission by contact;
• consider the use of washable face shields in combination with PPE in order to reduce the risk of contamination;
• sanitize your hands with alcoholic solutions or soap and water before and after touching or adjusting the position of the respirator (to improve comfort or to keep it in position for example);
• it is necessary to dispose of PPE that shows evident damage or does not allow the operator to breathe correctly ".

And where the limited reuse of PPE is foreseen, between one use and another of the respirator, "follow good practice guidelines , such as:

• remove the PPE in a dedicated place, avoiding touching the filtering part (remove the mask from behind the neck, touching the laces or elastic bands). The environment in which the removal of PPE takes place must be regularly sanitized. Perform the hand hygiene procedure before and after removing the PPE;
• keep the PPE inside a clean breathable bag such as a paper bag, taking care not to damage or deform it;
• each operator must clearly identify and mark their PPE and the container in which it is stored: avoid the accidental use of the same PPE by several operators;
• Use clean gloves when putting PPE back on or when touching it for inspections. Dispose of the gloves used to wear the PPE or to carry out the leak test;
• Carry out the tightness check at each new use.

It then states that “according to the indications available, when not specified by the manufacturer, it is suggested to reuse the PPE a maximum of five times . The masks with the wording "Disposable" ('FOR SINGLE USE') affixed by the manufacturer and the medical-surgical masks, CANNOT BE REUSED UNDER ANY CASE ".

Furthermore, based on the information currently available, “ we are not aware of any recognized effective methods that can be used to safely disinfect or sterilize all disposable PPE with face filter . Although numerous studies have been conducted on this subject that have shown that some disinfection methods are able to render infectious agents non-viable efficiently for some models of respirators, the effect of these methods on the level of degradation of the materials that constitute the PPE (and in particular on the filter medium) is not known. Eventually, only individual manufacturers can provide reliable indications on this particular aspect. Disinfection methods can lead to alterations of the PPE which can affect the level of protection. These changes may relate to performance (e.g. filtration efficiency) or adaptability (e.g. degradation of laces, nose clip material, accessories for straps) or a combination of these (e.g. metal components that heat up damage the filter material around to them) ".

In relation to what has been indicated, "the decision to adopt procedural measures that provide for the prolonged use or reuse of PPE for the respiratory tract should be taken on a case-by-case basis by the professionals who manage the institution's prevention and protection program (in accordance with information provided by the competent authorities), taking into account the known characteristics of the SARS-CoV-2 and some specific conditions (eg number of devices available, rate of use, etc.) of the reality subject to intervention ". And “the professional skills in order to prevent and protect the health of the general population and workers are of fundamental importance in choosing the most correct protection measures to be adopted”.

In conclusion, we refer to the full reading of the document which also contains instructions for wearing protective devices.