If you’ve kept up with consumer reports, you may be aware that the refrigerant used in some air conditioners has been targeted as an ozone-depleting substance.

The problem is that aging, sealed systems may develop leaks and allow the refrigerant to escape into the atmosphere. Prior to December 31, 1995, a common refrigerant in older cars, some commercial air conditioners, and certain refrigerators was CFC-12 or R-12

Now, the commonly used refrigerant in home air conditioners is R-22, an HCFC (hydrochloro- fluorocarbon) that is safer but can still be a problem if it reaches the stratosphere. Production of HCFCs will be phased out eventually, too.

The refrigerant used in new car air-conditioning systems is R134a, an HFC (hydrofluorocarbon) that does not contain ozone-damaging chlorine atoms. Carrier was the first manufacturer to produce a residential central air-conditioning system—the WeatherMaker 134a—that uses this refrigerant. Other manufacturers are also introducing similar systems.