Ключевые слова: air, asia, background, beijing, boy, breath, breathing, care, child, city, cough, danger, dirty, dust, ecology, emission, environment, environmental, face, filter, girl, growth, harmful, hazardous, health, hygiene, industrial, infection, kid, life, mask, medical, medicine, mist, mouth, people, person, pollution, prevention, protect, protection, protective, sick, smog, smoke, street, urban, virus, young,