You're asking the wrong question. A better question would be 'when did the concept of 'patient care areas' get expanded so?'
The whole point of the original patient care area rules was to codify what had already become standard practice in areas where explosive anesthetic gasses were used; you didn't want a static charge to build up anywhere.
As an example, an 'oral surgeon' would probably need Article 517 practices in his operating area, while a dentist would not see the need.
Since then, we've lost sight of this. We've expanded 'patient care area' practically to the parking lot, while medicine has nearly completely got away from chloroform, ether, and the other explosive gasses.