Ключевые слова: adult, air, bad, be worth, be worthwhile, care, chemical warfare, contamination, course particle, cover, disease, doctor, environment, epidemic, escort, face, female, final particles, flu, gas, guard, healthy, human, infection, influenza, mask, medical, medicine, n95, particulate matters, people, pm 25, pollution, pollution control, prevent, prevention, problem, protect, protection, protective, quality, respiratory, respiratory care, respiratory protection, safeguard, safety, shield, sick, virus, weather,