air
background
blue
brume
carbon
chemistry
chimney
chimneystack
closeup
contamination
content
cooling
damage
danger
defilement
duct
emissions
environment
factory
fog
fume
funnel
high
impurity
industry
mist
pipe
pollution
products
reek
refuse
sky
smog
smoke
smokestack
soot
stack
steam
tailings
toxic
trumpet