Ключевые слова: air, atmosphere, background, bear, boy, breathing, brick, chemical, city, climate, concept, danger, difficulty, dioxide, dirty, ecology, emissions, environmental, factory, garbage, gas, gas mask, global, health, hood, hug, industry, lungs, man, medicine, noise, people, pollution, power, problem, production, protection, ruins, sadness, safety, smog, smoke, steam, technology, tinting, toxic, toy, urban, wall,