Types of mask

In general, there are three types of masks based on their ability to filter inspired or exhaled air, and therefore, based on their ability to protect the user of the mask and / or the rest of the population from contagion in case from an airborne infection:

• Surgical masks: These are masks for medical use, used by healthcare professionals in surgery and other procedures in order to protect the patient from possible infectious agents present in the nasal or oral cavity of the mask user. These surgical masks may also be intended to be worn by patients and others in order to reduce the risk of spreading infections, particularly in pandemic situations such as COVID-19. They basically act as a barrier to prevent the emission of respiratory droplets when sneezing or coughing.

These masks, therefore, can prevent the transmission of the infectious agent from an infected person to other healthy people, but their effectiveness in preventing contagion to the user of the same seems more limited, with less scientific evidence in this regard.

Filtering masks (also called self-filtering): They contain a microparticle filter thanks to which they can protect the user of the mask against the inhalation of environmental pollutants - in particles or aerosols - such as pathogens, chemical agents, antibiotics, cytostatics, etc. They do not protect against gases or vapors, although there are masks with specific filters for those cases.

They are classified based on their performance in:

1. FFP1 (particle filter type P1): they have a minimum filtration efficiency of 78% and a maximum inward leakage percentage of 22%. They are usually used against particles of inert material, and are not recommended for medical use.
2. FFP2 (P2 type particulate filter): they have a minimum filtration efficiency of 92% and a maximum inward leakage percentage of 8%. They are used against aerosols of low or moderate toxicity.
3. FFP3 (particle filter type P3): they have a minimum filtration efficiency of 98% and a maximum percentage of leakage into the interior of 2%. They are used against highly toxic aerosols

Self-filtering masks may or may not have an exhalation valve to reduce moisture and heat within the mask, providing greater comfort to the user and offering the sensation of less breathing resistance. These valve masks should not be used in sterile environments, nor in the case of patients infected with COVID-19, since they could transmit the virus through the valve, except in the case that the valve is protected or designed to avoid said transmission to the outside.

These FFP2 and FFP3 filter masks will therefore protect the user against COVID-19 infection. In addition, they could prevent transmission from the user to the outside, if they were designed to do so.

Hygienic or barrier masks: They are intended for people without symptoms who are not likely to use surgical or filtering masks, based on the recommendations established by the Ministry of Health in its technical document "Prevention and control of infection in the management of patients with COVID19 ”and in those situations in which the shortage of masks for medical use may make them recommendable.

The objective of its use in the COVID-19 pandemic is to try to reduce the risk of transmission of the virus from the mouth and nose of the non-ill or asymptomatic user, as a complementary measure to other preventive measures approved by the health authorities.

Although there is not enough evidence available to draw solid conclusions, it seems that this type of mask has a very limited effectiveness in preventing contagion by the user, and in any case, it depends on the material from which it is made.

There are two types of hygienic masks:

Non-reusable: These masks are governed by the UNE 0064-1 Specification (non-reusable mask for adults) and the UNE 0064-2 Specification (non-reusable mask for children).

Reusable: These masks are governed by the UNE 0065 Specification (reusable masks for adults and children). In the case of reusable hygienic masks, the mask should be washed and dried according to the manufacturer's recommendations. After each wash, a visual inspection should be carried out in case any damage is detected.

In the case of reusable hygienic masks, they must comply with the specifications included in Specification UNE 0065, according to which the mask must be able to withstand at least 5 washing and drying cycles while maintaining its performance. After this process, the manufacturer must be able to guarantee that the reusable hygienic mask meets the specified criteria.

In the event that this type of mask is washed, the following aspects should be taken into account:

• The washing and drying of the mask must be in accordance with the manufacturer's recommendations.
• Contact between a dirty mask (to be washed) and clean clothing should be avoided.
• The person in charge of the wash must protect themselves to handle dirty masks.
• Products that can degrade or damage the materials and that diminish their protective capacity should not be used.
• It is recommended that the mask dry completely within 2 hours after washing.
• It should not be dried or sanitized with a microwave oven.

Both during drying and subsequent storage of the mask, environments in which the mask can become contaminated again should be avoided.

After each wash cycle, a visual inspection should be performed (with protective gloves or washed hands).

If any damage to the mask is found (less fit, warping, wear, etc.), the mask should be discarded.

Both surgical and filtering masks are considered non-reusable.

If a mask is used, it is essential to use and dispose of it correctly to be effective and to avoid the increased risk of transmission associated with improper use and disposal.

In this regard, WHO provides a series of general advice, such as the following:

• Apply the mask carefully so that it covers the mouth and nose and tie it tightly so that there are no gaps with the face.
• Do not touch it while it is being worn.
• Take it off with the correct technique (unknotting it at the nape of the neck without touching its front part).
• After inadvertently removing or touching a used mask, wash your hands with a hydroalcoholic solution, or with soap and water if they are visibly dirty.
• As soon as the mask is damp, replace it with a clean and dry one.

In general, single-use masks should be disposed of immediately after use, without reusing.

If any possible disinfection method is used for reuse, on which there is still not enough evidence to recommend them, it should be carried out on individual masks and consider that the possible reuse of masks is always by the same person.