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air
alphabet
atmosphere
backdrop
background
ban
block
business
certified
cfc
chemical
chlorofluorocarbon
compound
concept
danger
dangerous
depletion
design
earth
eco
element
environment
equipment
free
gas
global
guarantee
harmful
hazard
health
hydrocarbon
industry
label
letter
material
montreal
ozone
planet
pollution
production
protocol
qualified
safety
science
spray
volatile
warming
wood
word