building, industrial, acid, destruction, danger, ecology, poison, steam, smokestack, smoke, technology, smog, generate, brown, chimney, fuel, gas, dirty, pollution, air, dust, environmental, toxic, factory, energy, environment, grunge, industry, emission, pipe, plant, tower, global, hot, power, atmosphere, manufacturing, warming, nature, sky, crisis, soil, air pollution, profession, engineering, egress, mill, cloud, unclean, dirtiness, impurity, tube, edifice, passage, application, suspension, particulate, conduit, mixture, dirt, difficulty, fabrication, soiled, column, flue, heating, environmental condition, situation, vapor