Sample Clues
The 1987 Montreal Protocol limits "substances that deplete" this in the atmosphere
ozone
This pollutant once used in gasoline & paint can lower the IQ of the person breathing its vapors
lead
Using natural gas as a fuel releases half as much of this greenhouse gas as coal
carbon dioxide
Founded in Calif. in 1892, this pro-environment group now has 180,000 members nationwide
the Sierra Club
A dangerous indoor air pollutant is particles from this nonflammable material once used in insulation
asbestos