air
atmosphere
background
blue
building
chimney
city
climate
construction
contaminate
contamination
dirty
eco
ecological
ecology
energy
environment
environmental
equipment
factory
field
fuel
fumes
generation
global
green
greenhouseeffect
high
industrial
industry
landscape
modern
nature
pipe
pipes
plant
polluting
pollution
power
problem
sky
smog
smoke
smokestack
station
steam
technology
toxic
warming
water