air
air pollution
atmosphere
bad ecology
blue
chimney
climate
co2
dioxide
ecology
emission
emitting
energy
environment
environmental
factory
factory pollution
factory smoke
fuel
fumes
gas
global
global warming
harmful
industrial
industry
manufacturing
metallurgical
pipe
plant
pollution
pollution city
power
power plant
power station
production
sky
smog
smoke
smoke factory
smokestack
stack
steam
toxic
urban
vapour
warming
white
white smoke