air
atmospheric
bituminous
black
blue
calorific
central
city
coal
crock
disaster
dust
ecology
effect
emission
environment
environmental
factory
filter
fume
gas
green
greenhouse
heat
house
illness
industry
lung
mask
ozone
pipe
plant
pollution
power
problem
respirator
respire
sickness
sky
smoke
soot
stack
station
steam
technology
thermal
warming
water
white