The ozone layer is destroyed by chemical reactions in the upper atmosphere. Ozone is destroyed when it reacts with chlorine (Cl) or bromine (Br). Chlorine and bromine get into the atmosphere when humans use molecules called chlorofluorocarbons (CFC, for short). We use CFC molecules in many things such as air conditioners, fire extinguishers, and hairspray canisters. Every time we use these items, some CFC molecules can travel into the atmosphere and destroy the ozone layer. However, it is now against the law to make CFC products.

The ozone layer in the upper atmosphere is important because it protects us against radiation from the sun. However, ozone can increase global warming when it is in the lower atmosphere (near the surface). Therefore, ozone is helpful when it is higher in the atmosphere, but it is harmful when it is in the lower atmosphere. Other gases (like carbon-dioxide and methane) are more effective for increasing the surface temperature of the Earth than the disappearing ozone layer.