air
atmosphere
blue
catastrophe
chemical
chimney
cleanliness
climate
cloud
contaminate
contamination
damage
danger
dirty
disaster
ecological
ecology
emission
emit
energy
environment
environmental
factory
fume
gas
global
gray
greenhouse effect
human
industrial
industry
landscape
ozone
pipe
plant
poison
polluting
pollution
problem
protection
risk
sky
smog
smoke
smokestack
steam
technology
toxic
warming
water