Every time we utter just a couple of words, we spray thousands of aerosol droplets, which are mostly invisible to the naked eye, into the air in front of us.
Some professional singers can create an aerosol cloud up to 1.4m in front of them. Larger droplets– more like little globules of spit fly forwards and downwards to land on surfaces about 1.5m away. Coughing could send aerosols even further up to 1.9m, while other studies have shown that a sneeze can project aerosol clouds up to 8m away.
While larger droplets fall quickly to the ground or other surfaces, microdroplets can remain suspended in the air for several minutes or even hours.
Unlike WHO, many scientists now believe that airborne aerosols carrying the coronavirus may play a major role in spreading Covid-19.
At present, virologists are collecting more and more clinical evidences that tell masks catch infectious particles produced from speaking, coughing, or sneezing, which may reduce the risk of infecting another person. Proper wearing of a face mask could thus help to reduce the spread of COVID-19 and protect risk groups from infections in a cheap and simple way.
The Center for Disease Control and Prevention (CDC) For the first time has recommended that even healthy people should wear masks over their mouths and noses into places where it is difficult to maintain distance from other people. But there is still a main question how much masks particularly the homemade fabric masks that the CDC recommends for the public can slow the spread of SARS-CoV-2, the virus that causes COVID-19.
-Surgical masks
Surgical masks are made up of several layers of non-woven plastic and can effectively filter very small particles, such as droplets of SARS-CoV-2. The masks typically contain an external waterproof layer and an internal absorbent layer.
A surgical mask (medical mask) is a loose-fitting disposable mask that protects the wearer’s nose and mouth from contact with droplets, splashes and sprays. A surgical mask also filters out large particles in the air. Surgical masks may protect others by reducing exposure to the saliva and respiratory secretions of the mask wearer. At this time, it is not approved any type of surgical mask specifically for protection against the coronavirus.
-N95 masks
Indeed a type of respirator, it offers more protection than a surgical mask because it can filter out both large and small particles when the wearer inhales. The mask is designed to block 95% of very small particles.
Some N95 masks, and even some cloth masks, have one-way valves that make them easier to breathe through. But because the valve releases unfiltered air when the wearer breathes out, this type of mask doesn’t prevent the wearer from spreading the virus..
-Cloth masks
Asking everyone to wear cloth masks can help reduce the spread of the virus by people who have COVID-19. It traps droplets that are released when the wearer talks, coughs or sneezes. Masks can be made from common materials, such as sheets made of tightly woven cotton. Cloth masks should include multiple layers of fabric.
-Face shield
Plastic visors are widely used by people to protect from the coroavirus. But face shields appear to be only truly effective in ideal conditions. In these situations they estimated that the visor is only 45% effective at blocking droplets.
masks are an imperfect defense against the coronavirus but evidence has mounted that, when combined with social distancing, eye protection, and frequent hand washing, they can slow its spread. Their primary benefit is not to an individual wearer, but to others. When a mask wearer coughs, sneezes, or simply breathes, the mask acts as a barrier that blocks the flight of virus-laden droplets. A lot of the droplets never make it out, and then the ones that do don’t go very far.
-In activities
when you are in an area of COVID-19 transmission, masks should not be worn during vigorous physical activity because of the risk of reducing your breathing capacity. No matter how intensely you exercise, keep at least 1 meter away from others, and if you are indoors, make sure there is adequate ventilation.
-Last but not least
The wearing of a mask may make people feel safer, and hence minimise other protective behaviours which known to be effective, such as social distancing and regular hand washing.
Then, masks need to be worn correctly and consistently and in a good level of adherence when in contact with other people. Also masks may act as an extra transmission source or route to transmit the virus, such as regular face touching.
