The goal throughout the revision process of Standard 62 has been to update the standard based on more recent information and to convert the 1989 standard into mandatory and enforceable language. This has been difficult at times, as some have pushed to make the standard more strict while others have argued it should contain the minimum requirements in order to be adopted by code bodies.
As can be expected, 62.1-2004 contains some significant changes from the previous version, including 17 new addenda. The major modifications involve changes to the ventilation rate procedure, changes in wording concerning environmental tobacco smoke, changes to requirements related to indoor relative humidity, and new outdoor air assessment and cleaning requirements.