air
background
blue
building
chemical
chimney
climate
clouds
coal
contamination
destruction
dioxide
dirty
ecology
energy
environment
environmental
exhaust
factory
fuel
fume
gas
global
high
industrial
industry
manufacturing
monoxide
nuclear
overcast
ozone
pipe
plant
poison
poisoning
pollute
polluting
pollution
power
production
reactor
refinery
sky
smog
smoke
smokestacks
station
steam
technology
toxic
tube
vapor
vapour
warming
waste