air
burning
carbon
carbon dioxide
chemical
chimney
city
climate
dioxide
dirty
ecology
emission
energy
environment
environmental
evaporation
exhaust
factory
fuel
fume
gas
generation
global
globalwarming
greenhouse
heating
heavy
hedgehog
industrial
industry
manufacturing
plant
pollute
pollution
power
power station
production
sky
smog
smoke
stack
station
steam
sunrise
sunshine
technology
tower
tree
vapor