air
atmosphere
black
burner
burning
catalyst
chimney
climate
climate change
co2
coal
complex
contamination
dark
dirty
ecology
electricity
emission
energy
environment
exhaust
factory
fog
fume
fumes
global
global warming
greenhouse
heating
heavy
industrial
industry
manufacturing
metal
pollution
power
process
production
sky
smog
smoke
smokestack
steam
structure
supply
technology
thermal
tower
toxic
vapor