One question that I have received quite often since the publishing of the 2012 edition of NFPA 99, Health Care Facilities Code, is whether or not windowless anesthetizing locations still require smoke purge systems. The answer to this is that the 2012 edition does not require it. What had previously been in NFPA 99 and previously NFPA 56A was language that remained essentially the same for years and was in the 2005 edition as follows:
“18.104.22.168 Supply and exhaust systems for windowless anesthetizing locations shall be arranged to automatically vent smoke and products of combustion.
22.214.171.124 Ventilating systems for anesthetizing locations shall be provided that automatically (1) prevent recirculation of smoke originating within the surgical suite and (2) prevent the circulation of smoke entering the system intake, without in either case interfering with the exhaust function of the system.”
My research shows this requirement to have first appeared in NFPA 56A in the 1960 edition. The way it was presented and worded has been slightly altered throughout the years but the intent that the smoke and products of combustion be vented and that recirculation be prevented had remained. When NFPA 99 was reorganized for the 2012 edition the requirement was not incorporated in the new Chapter 9, Heating, Ventilating, and Air Conditioning.
In the current revision process the technical committee on Mechanical Systems has proposed language that specifically states smoke purge is not required in windowless anesthetizing locations. The main substantiation for this is that the requirement is considered to be a relic as when it was first incorporated into an NFPA requirement the use of flammable anesthetics was common and therefore the fire hazards in these rooms was much higher.