air
atmosphere
breathe
chemical
chimney
climate
cloud
dirty
ecological
ecology
emission
energy
environment
environmental
factory
field
fog
fresh
fumes
future
gas
global
industrial
industry
landscape
mask
meadow
ozone
pipe
poison
poisonous
polluting
pollution
rain
sky
smog
smoke
smokestack
smoky
stack
steam
steamy
technology
toxic
toxicity
warming