Ключевые слова: air, atmosphere, bad, bus, buses, car, carbon, cars, clean, climate, cloud, co2, commercial, dioxide, dirty, ecology, effect, emission, emissions, energy, environment, environmental, environmental friendly, factory, fuel, fumes, gas, global, industry, low, oxygen, poison, pollutants, polluted, pollution, protecting, protection, restriction, sign, smoke, steam, symbol, technology, traffic, transport, transportation, warming, warning, waste, zone,