Fluorinated gases pharmaceutical industries, as well as in refrigeration when combined with other gases. PFCs were commonly used as fire extinguishants in the past and are still found in older fire protection systems. They are also a by-product of the aluminium smelting process. Sulphur hexafluoride (SF) is used primarily as an insulation gas. It can be found in high-voltage switchgear and is used in the production of magnesium. HFCs were developed in the 1990s to substitute substances such as chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs). As these substances were found to deplete the ozone layer, the Montreal Protocol lays down provisions for them
Wiley protocol at separate times throughout the period. The protocol is promoted as differing from conventional hormone replacement therapy in several ways: The protocol also includes a follow-up program to monitor the serum of the bioidentical hormones. Wiley has stated that in her opinion, the most important aspect of the protocol is the specific schedule and levels of the hormone doses rather than their bioidentical nature. A patent was granted for the protocol in 2011 for the specific blend of hormones and dosing method. Concerns have been raised that serum levels may not be an acceptable marker for transdermally administered hormones, that