Any gas, such as carbon dioxide, methane, or CFCs, that contributes to the greenhouse effect when released into the atmosphere.
Hypernym: greenhouse gas
An allotrope of oxygen (symbol O₃) having three atoms in the molecule instead of the usual two; it is a toxic gas, generated from oxygen by electrical discharge.
Fresh air, especially that breathed at the seaside and smelling of seaweed.
To treat with ozone.