Ключевые слова: air, allergy, breathing, care, clean, concept, control, cough, danger, disease, dust, environment, epidemic, equipment, examining, face, filter, flu, health, health care, healthy, infection, influenza, isolated, medical, medicine, pandemic, polluted, pollution, prevention, protect, protection, protective, respirator, respiratory, safety, sick, sickness, surgery, surgical, virus, warning, work,