environmental
air
apple
ash
atmosphere
background
blossom
chemical
chimney
cleanliness
climate
clouds
contaminate
contamination
damage
dirty
ecology
emission
emit
energy
environment
factory
flowers
fumes
gas
global
greenhouseeffect
industrial
industry
landscape
nature
ozone
person
pipes
plant
poison
polluting
pollution
reflection
sickness
sky
smog
smoke
smokestack
steam
sunset
technology
toxic
tree
water