air
atmosphere
breathe
carbon
chemical
chimney
coal
condensation
contamination
damage
danger
dangerous
dioxide
dirty
ecology
emission
emissions
environment
environmental
factory
fume
gas
greenhouse
harmful
heat station
industrial
industry
manufacturing
plant
pollute
polluted air
pollution
power
production
refinery
sky
smog
smoke
smoke emission
steam
technology
urban
vapor
warming
waste