The greenhouse effect is caused by a gas that absorbs and emits heat infrared radiation, which is called a greenhouse gas.
The main greenhouse gases in the Earth's atmosphere include water vapour, carbon dioxide, methane, nitrous oxide, and ozone.
Because ozone in the stratosphere absorbs heat transmitted to space by gases in a lower layer of Earth's atmosphere, the ozone hole has a tiny cooling effect approximately 2% of the warming effect of greenhouse gases (the upper troposphere).
Because it has no effect on the earth's temperature, ozone (O3) is not a greenhouse gas.