accord
agreement
air
atmosphere
black
building
carbon
chemical
chimney
china
climate
clouds
co2
danger
dioxide
dirty
ecology
emissions
energy
environment
environmental
exhaust
factory
fuel
fume
gas
global
greenhouse
industrial
industry
mill
ozone
paper
paris
plant
pollute
pollution
production
refinery
smog
smokestack
stack
steam
tower
toxic
urban
vapor
warming
waste
white