It turns out that only three groups of people should wear masks.The World Health Organization has issued recommendations for medical masks. According to WHO people without respiratory symptoms (such as coughing) should not wear a medical mask. However, the usage of these products is recommended for specialists who work with people who have signs of acute respiratory symptoms such as cough, fever, runny nose and so on.
Healthy people who attend patients with a coronavirus diagnosis should always use respiratory masks. They should be changed after each contact with a sick person and this contact should last no longer than 15 minutes.
So, masks should be used by medical workers, by people with respiratory symptoms and by people who take care or communicate with infected persons.