air
atmosphere
breathe
carbon
chemical
chimney
chimneys
climate
cloud
coal
contamination
danger
dioxide
dirty
ecology
emission
energy
environment
environmental
exhaust
factory
fume
gas
global
harmful
ice
industrial
industry
landscape
ozone
pipe
plant
pollute
pollution
power
production
refinery
river
silhouette
sky
smog
smoke
stack
steam
technology
tower
toxic
vapor
warming
white