The article discusses how the phase-out of certain chemicals in fridges and air conditioners is happening. People are starting to use different, safer chemicals instead. These new chemicals might be toxic, flammable, or build up a lot of pressure. People who work on these machines need to be very careful. The article gives an overview of these new chemicals and when it's ok to use them. It also says that it’s better to use these new chemicals in new machines, not old ones. People need to follow these rules to make sure things stay safe.