background
blue
building
chemical
chemistry
chimney
clouds
construction
crude
distillation
ecoligical
energy
engineering
environment
equipment
factory
fuel
gas
gasoline
grey
industrial
industry
large
manufacturing
metal
oil
petrochemical
petrol
petroleum
pipe
pipeline
plant
pollution
polution
power
problem
production
refinery
sky
smoke
steel
storage
tank
technology
tower
toxic
under
white
worker