Respirator Masks (N95, N99, N100; FFP1, FFP2, FFP3)
A respirator mask is a tight-fitting mask with a filtration system that prevents the wearer from being exposed to noxious particles, gases, oils or microorganisms, including bacteria, viruses and fungi. It has two specific characteristics that is, an air filtering system that prevents the passage of noxious substances and microorganisms from entering inside the respiratory tract, and a tight fit so that air does not leak from the sides into the nose and mouth.
The filter of the N95 mask is made up of millions of microfibers of polypropylene layered on top of each other that have been permanently electrostatically charged. The electrical charge is necessary to retain its ability to filter microorganisms or microparticles.
The respirator masks were first developed for occupational exposure settings to reduce exposure to fine particulate matter pollutants, but they were modified later to cover harmful gases and volatile oils. In 1972, 3M introduced the first, single-use N95 mask, which instead of fiberglass was made up of very thin layers of fibers by air-blasting melted polymer. They then added an electrostatic charge to the material in order to block very small particles. The breathing was a lot easier with this mask, and it soon became a popular personal protective devise for fine dust exposures. Its first medical application was during the 1990s when it was used by doctors and nurses to protect them from catching drug resistant TB from HIV-infected patients. It was then subsequently used in the SARS outbreak in 2003.
Respiratory masks are certified into N, R or P depending on their ability to offer resistance to oil-based particles. N is further divided into N95, N99, N100 depending on the filtration efficacy.N95 means that this mask can filter off at least 95% of particles while N99 means it can filter off 99% of these particles.
The N95 mask should be NIOSH approved and CE certified. NIOSH has a website which has a list of certified licenses holders to manufacture the N95mask. The important thing to identify is the TC number on the particular mask. Each country has their own certification standard for each mask type, e.g. USA [NIOSH 42CFR Part 84], Europe [149:2001, China [GB2626].
N95 and similar masks are efficient in protecting the wearer against viruses, they are not easy to breathe and often get moist and hot after wearing it for more than 30 minutes. They are therefore not meant for routine household use or while travelling outside, they are mainly meant for health care providers who come in close contact with the COVID19 patients.
Respirator Masks with Valve
N95 and other respirator masks are also available with a valve and without a valve. The valve N95 mask respiratory are not suitable for patients suffering with COVID-19 as during exhalation they will allow the virus to pass out easily and can potentially infect neighboring people, but it can be recommended for people with Lung disease/ Heart disease.
Early in the pandemic, major problems in the global supply of medical grade masks, at that point, bodies such as the US Centers of Disease Control and Prevention (CDC) recommended that the public wear cloth masks and even provided information on how to make them out of household items. Surgical masks need to be replaced every day. N95 masks are expensive, not easily available and are largely meant for frontline healthcare providers. For the vast majority of people in the community, especially from developing countries, there is a need for a cheap, easily available, washable and reusable mask. Cloth masks seem to fulfill these criteria. WHO advises an inner absorbent material such as cotton, a non absorbent fabric such as polyester outside, and a middle filter layer, such as non-woven spun bond polypropylene.
When wearing the mask, ensure that there is no or minimal gap between the face and the mask. Avoid touching the mask while using it, and if you do, clean your hands with soap and water or alcohol disinfectant. If the mask becomes damp or gets soiled, dispose it off in a closed bin. When removing the mask, remove it from behind without touching the mask and discard it immediately in a closed bin. Again, wash your hands with soap and water or alcohol rub.
Who should wear masks and which one?
It is advisable that in community everybody should wear a mask, primarily because this is the best means of preventing the aerosol spread of infection from one person to another and also because it offers some protection from catching infection from others.
The N95 mask reduces the transmission of aerosol by 70%, whereas surgical mask reduces transmission by 50% and cotton masks by 40%. Maximum protection from catching the infection from others by the aerosol route is offered by the N95 mask (99%), whereas the surgical mask offers 75-80% protection and the cloth mask by around 50-70%. Wearing any mask is better than wearing no mask, both in terms of transmission and protection.
When outside the house
Everybody must wear a mask during the ongoing pandemic. The surgical mask is the preferred mask, but this needs to be replaced daily or even multiple times daily depending on the time spent outside, the weather and humidity. Surgical masks that become wet soiled or makes breathing difficult, must be replaced immediately.
The surgical mask should never be washed nor reused anytime. If the surgical mask is not available or is unaffordable, a washable and reusable 3-layer cloth mask should be used. It should be washed everyday with soap and warm water and air dried. The mask should be stored in a clean and dry place.
When inside the house
If you have respiratory symptoms suggestive of corona virus infection (fever, sore throat, dry cough, shortness of breath, body ache or loss of smell) you must wear a surgical mask at all times, even while sleeping. It should be replaced preferably at least every 4-8 hours until seen by a physician. Care should be taken not to touch the mask with the hand and should be disposed carefully in a closed bin.
If the surgical mask is not available or not affordable, you should wear a washable and reusable 3-layered cloth mask, which should be carefully washed and dried. All other members in the family should also wear a surgical mask or a cotton mask depending on availability and affordability. If you are asymptomatic, but have come in close contact with somebody who travelled from abroad or having flu like symptoms, you should wear a surgical mask / cloth mask. If nobody in the house has any respiratory symptoms or no one has been in touch with anyone who travelled from abroad, there is no need to wear a mask.
If a person is recovering from COVID-19 infection, he must wear a surgical mask. Everybody else should wear a surgical mask and if that’s not feasible, then they should wear a 3-layered cloth mask. Social distancing and hand hygiene must be practiced strictly.
To conclude, it becomes necessary for all to wear a mask, primarily because it significantly reduces the chances of spreading the aerosol route of transmission, and also because it offers protection against catching the infection. It is our joint responsibility to prevent the spread of infection.
Wear Mask and Stay Safe.
(The Author is Anaesthetist. Currently working at GMC associated DRDO COVID Hospital Srinagar)