catalyst
chemical
chimney
construction
corporation
dark
dirty
distill
dusk
emission
energy
engine
environment
factory
fog
fuel
gas
gasoline
global
industrial
industry
landscape
light
manufacturing
metal
nature
oil
petroleum
pipe
pipes
plant
pollution
port
power
production
refinery
site
sky
smog
smoke
steam
steel
structure
sunset
technology
toxic
urban
view
warming
winter