Answer: Air pollution.
Air pollution occurs when harmful substances are introduced into the atmosphere. These substances majorly exist in two forms i.e solid ( particulate matter in air) and gaseous form.
CFCs (Chlorofluorocarbons) are compound consisting of Chlorine, fluorine, and carbon atoms. They are released in the atmosphere through aerosol sprays, air conditioners, refrigerators etc. Due to longer lifespan in the stratosphere, they can cause damage to the ozone layer thereby reducing earth's protection from harmful UV radiation. Also, they have warming effects which may cause global warming.
Smog is primarily named for the mixture of smoke and fog in the air. It is a blackish fog formed in the atmosphere mainly due to the reaction of various gases with dust and water vapors. it causes breathing difficulty and other harmful consequences.