air
catalyst
chemical
chimney
city
complex
corporation
distill
dusk
ecology
emission
energy
environment
exterior
factory
fog
fuel
gas
industrial
industry
landscape
manufacturing
metal
nature
night
oil
petroleum
pipes
plant
pollute
pollution
port
power
production
refinery
silhouette
sky
smog
smoke
stack
steam
steel
structure
sunset
technology
tube
urban
view
warming
winter