Quite often in the period of an outbreak of SARS or influenza it is possible to observe whole crowds hoping to protect themselves from viruses, in gauze, cotton-gauze, and also modern disposable bandages from non-woven materials. But how effective is this method of preventing SARS?
Viruses show a huge variety of shapes and sizes. As a rule, they are much less bacteria (the size of the average virus is about one hundredth of the size of the average bacterium) and have a diameter ranging from 20 to 300 nm (2e-5 mm to 0.0003 mm). Most viruses are too small to be clearly distinguishable under a light microscope.
Now imagine a gauze bandage, and immediately it becomes clear that even folded 10 times it is not able to stop the tiny viruses. So on a healthy man the mask is useless. Moreover, if you forget to change it in time-it becomes a perfect drive of those viruses, which are then inhaled by a healthy person. More effective prevention in this regard should be considered adherence to the rules of personal hygiene, namely frequent washing of hands and face (especially after visiting public places).
Next, you should understand: does it make sense to wear a mask to the patient? Let's recall the ways of transmission of SARS (which was described in detail here). Viruses spread to other people through everything that concerns the mouth or nose (cups and cups from which the patient drank; his hands covering his mouth during a cough or wiping the nozzles with a handkerchief; the handkerchief of the patient, etc.). One of the main sources of infection are the drops of mucus and phlegm, which can fly a few meters when talking, coughing, sneezing, smorkanii. and viruses can be transmitted as directly airborne by another person, and settle on household items, where they live for some time while waiting for the contact path of infection.
Thus, if a person suffering from SARS covers his mouth and nose with a mask or handkerchief when coughing and sneezing, it can help limit the spread of the infection. However it is necessary to remember that to provide 100, 1% protection of surrounding from a virus the mask is not in a condition as the patient continues to breathe, and the ordinary breath is enough for that air containing viruses and exhaled by one person, became inhaled air for another person (the size of the virus and "holes" in the mask we have already compared). Besides, it is necessary to remember that the mask very quickly soaked phlegm and actually becomes a reservoir of viruses, therefore, masks it is recommended disinfect boiling, intensively thextil iron and to change at least in 4 hours. Also it is not necessary to scatter used masks and handkerchiefs where other people can touch them.
In connection with the stated we conclude that for the prevention of SARS mask should be worn not healthy people, and patients. And efficiency will be achieved only in case of its timely replacement.
However, the question remains: why do all medical personnel wear masks and require them to be worn from visitors during outbreaks of viral diseases? Let's not forget that each person is a potential carrier of viruses and bacteria, even if he has no symptoms (including in the incubation period of the same SARS). For a person already sick (i.e. Whose immunity is weakened by the fight against the disease) is absolutely no need to get a portion of fresh viruses and bacteria. Accordingly, the recommendation to be in the hearth of ARI in masks and healthy, and sick has some rational grain, but with the prevention of SARS for a healthy person is not particularly related.
The alternative for healthy some experts consider medical respirators (more dense, than masks, with a valve of exhalation). However, it is worth noting that breathing in this device is not easy, so use it should only be a high probability of infection.