air
atmosphere
challenge
change
chemical
chemistry
chimney
climate
climate change
coal
concern
contamination
corporate
damage
dioxide
dirty
ecology
electricity
emission
energy
environmental
factory
fuel
fume
gas
global
heaven
heavy
industrial
industry
manufacturing
metallurgy
panorama
pipe
pollution
power
production
refinery
smog
smoke
smokestack
steam
steel
structure
technology
tower
toxic
warming