R-22, the refrigerant commonly found in older air conditioning systems, is being phased out by the EPA due to a byproduct that it produces which contributes to ozone layer depletion. A new refrigerant, R-410A, is one alternative refrigerant that is approved by the EPA. When installing new units and servicing older units, all R-22 must be drained and disposed of responsibly. Be sure that your HVAC contractor is adhering to the EPA's guidelines when handling and disposing of R-22.

Thanks to Dallas HVAC contractor ACDoctor for the tip.