against
air
atmosphere
background
blue
chemical
chimney
clean
climate
dioxide
dirty
ecology
energy
environment
environmental
factory
global
health
industrial
industry
line
modern
nature
nobody
old
pipe
plant
pollution
power
production
red
sky
smog
smoke
smokestack
stack
stacks
station
steam
technology
thermal
thick
tower
tube
urban
vapor
warming
white