air
atmosphere
blue
building
carbon
chimney
clear
contamination
damage
danger
dioxide
duct
ecology
emission
energy
environment
exhaust
factory
fumes
generation
high
industrial
industry
manufacturing
old
one
pipe
plant
pollute
pollution
power
production
single
sky
smoke
smokestack
stack
steam
technology
tower
toxic
tube
urban
vapor
warming
waste
white