environmental
air
atmosphere
blue
carbon
chemical
chimney
city
clear
climate
condensation
danger
dioxide
dirty
ecology
energy
environment
exhaust
factory
fog
fumes
gas
global
high
industrial
industry
manufacturing
milieu
nature
outdoors
ozone
pipe
plant
pollution
power
red
refinery
sky
smog
smoke
smokestack
steam
substance
technology
toxic
tube
warming