against
air
atmosphere
background
blue
chemical
chimney
clear
climate
cloud
coal
construction
contamination
day
dioxide
dirty
ecology
electricity
emissions
energy
environment
environmental
exhaust
factory
fuel
gas
global
high
industrial
industry
manufacturing
nature
pipe
plant
pollution
power
red
sky
smog
smoke
stack
station
steam
technology
thermal
tower
toxic
vapor
warming
white