Ключевые слова: air, atmosphere, background, blue, carbon, change, chemical, chimney, climate, cloud, co2, conservation, danger, dioxide, dirty, ecology, effect, emission, emissions, energy, environment, environmental, factory, fuel, gas, global, industrial, industry, nature, ozone, pipe, plant, pollution, power, reduction, sign, sky, smog, smoke, steam, symbol, technology, toxic, warming, warning, white,