機器
air
architecture
building
business
chemistry
chimney
complex
crane
economy
energy
engineering
environment
environmental
equipment
exterior
facility
factory
grey
hazy
industrial
industry
iron
issue
landscape
machinery
manufacturing
material
metal
mill
outdoor
piping
plant
polluted
pollution
process
produce
production
site
steel
steel mill
structure
supply
technical
technology
tower
toxic
utility
work
working