air
building
chemical
clear
coal
damage
distillation
dust
energy
environment
environmental
factory
field
fossil
fuel
fumes
gas
gasoline
global
green
health
heat
hong
industrial
industry
kong
nature
oil
plant
pollution
power
problem
refinery
scene
sky
smoke
stack
station
steam
steel
storage
substance
tank
tower
town
toxic
urban
warming
waste