air
atmosphere
blue
boiler
boiler room
chimney
city
clear sky
climate
coal
condensation
construction
contamination
danger
day
ecology
electricity
equipment
factory
frost
fuel
fume
grey
heating
hot
house
industrial
metal
modern
outdoors
ozone
pipe
pollution
power
power station
sky
smog
smoke
smokestack
station
steam
steel
sunlight
technology
tower
tube
urban
vapor
winter