To Mask or Not to Mask

There seems to be some resistance to the wearing of masks on the Estate by some of the residents when they are off their properties, particularly while exercising.

What is known is that to contract Covid19, one Covid19 virus entering your nose or mouth will not give you the disease, you need to get an “infective dose”, which may be thousands of Covid19 viruses. These may be contained in a single droplet of moisture in expired air.

People with Covid19 shed viruses into the fluids of the respiratory tract and saliva which get expelled when they exhale, cough or sneeze. These viruses are contained in fluid droplets ranging from less than 10 microns (called aerosols) to much larger droplets up to 100 microns and larger. It is these larger droplets containing large doses of virus that are the main transmitters of person to person Covid19.

These larger droplets can travel some distance from the infected person with forced breathing as with heavy exercise and much further with sneezing and coughing. Out of interest a good sneeze has a muzzle velocity of 50 meters per second and can spray droplets as far as 6 meters.

So why bother with a mask, you feel fine and definitely do not have Covid19. Well, that is where the problem comes in. Many people with Covid19 have no symptoms at all, so the infected person feels absolutely fine, but guess what – he or she  can still be a transmitter of the corona virus and infect others. In addition, infected people can transmit the disease well before any symptoms start. So if we really want to protect ourselves from Covid19 we need to regard everyone we see as being Covid19 positive.

In order to both protect ourselves and others that we come into contact with,  we need to wear a mask. All masks and buffs covering the nose and mouth will stop most of the larger droplets being expelled into the atmosphere. They will certainly stop them being projected any distance from the wearer. Aerosols will pass through most masks, but research has shown that the aerosol virus load inside the mask is 4 times more than outside the mask. So a mask causes a 4 fold reduction in the aerosol virus load.

The same applies to a healthy person (Pete) in the vicinity of an infected person wearing a mask (John), John’s mask will stop most of the virus, not all, so the few virus containing droplets that escaped John’s will get caught on the outside of Pete’s mask greatly reducing the chance of Pete getting the infection.

Criticism of masks – air escapes around the sides – yes this happens, but the main infection problem is the infected droplets expelled directly away from the infected person. For air to escape around the side of a mask, it is exhaled from the nose or mouth, hits the mask and is deflected out of the sides. Large and small droplets tend to stick to the mask with the deflected air having a much lower virus load and is not projected away from the wearer.

Masks cause a buildup of carbon dioxide which is harmful to the wearer – If that were the case why are the surgeons and theatre nurses not affected – they have been wearing masks for many hours a day for the past 70 or more years.

It has been mentioned that your breathing is compromised if you are exercising heavily and your oxygen demand is high, in this case have a buff or mask around your neck and pull it over your nose and mouth whenever you come within 3 to 4 meters of another person.

When you return home after exercise or being in a public space treat your mask as infected and wash it before using it again.

 

Image: Stock