A chlorofluorocarbon (CFC) is a gas used for various purposes including solvents, refrigerants, and aerosol sprays. They are organic chemicals and contain carbon, hydrogen, chlorine, and fluorine. They were much used in the middle of the 20th century, replacing chemicals that were toxic or flammable or had other problems. In 1978, Sweden became the first country that banned CFC products. Later, the US and Canada did the same. Now, CFC products are not allowed in most countries, because they cause ozone depletion. CFCs are also greenhouse gases. An alternative to chlorofluorocarbons is hydrofluorocarbons (HFCs). These do not destroy the ozone layer or increase global warming.