environmental
air
architecture
background
blue
building
clouds
complex
construction
day
development
dirt
dirty
ecology
energy
environment
exterior
factory
heavy
high
history
industrial
industrialized
industry
manufacturing
moody
nature
old
outdoor
ozone
pollution
poor
power
produce
production
scene
single
sky
smog
smokestack
stack
steel
symbol
technology
thoroughfare
tower
toxic
tube
view
work