air
atmosphere
blue
chemical
chemistry
chimney
city
climate
cloud
coal
damage
dioxide
dirty
ecology
electricity
emission
energy
environment
environmental
equipment
exhaust
factory
fuel
fumes
gas
global
industrial
industry
manufacturing
pipe
plant
pollution
power
power plant
production
red
refinery
sky
smog
smoke
smokestack
stack
station
steam
sunset
technology
tower
toxic
warming
white