air
atmosphere
blue
building
chemical
chemical plant
chemistry
chimney
climate
cloud
construction
damage
dangerous
ecology
emission
energy
engineering
environment
environmental
equipment
exhaust
factory
fuel
fumes
global
heavy
industrial
industry
iron
manufacturing
metal
pipe
pollution
power
problem
protection
sky
smog
smoke
smokestack
steel
tall
technology
tower
toxic
trouble
tube
two
warming
white