Humidity and Temperature in Central Supply

Q: I’m working with a hospital on their temperature and humidity monitoring in their Central Supply area, and was wondering what specific parameters they should follow in the two different areas of Central Supply/Storage; and Decontam Area? Should the FGI Guidelines be followed or should the AAMI guidelines be followed?

A: If the organization is CMS certified, all CMS requires on the subject is found in standard §482.41(c)(4) which says “There must be proper ventilation, light, and temperature controls in pharmaceutical, food preparation, and other appropriate areas.” In their Interpretive Guidelines section, they identify the FGI Guidelines as an acceptable standard to incorporate. While they do reference other standards, such as AORN, OSHA, CDC, and NIH, they do not mention AAMI. So, it would seem acceptable to use the FGI Guidelines in this application. Could your client use AAMI guidelines instead? Yes, but they may have to defend this decision (through the use of risk assessments) to surveyors and inspectors.

The interesting thing with CMS is their standard §482.41(c)(4) does not specifically state that the use of the FGI Guidelines are for new construction and renovation only. This has led to some erroneous findings by state agencies performing validation surveys on behalf of CMS whereby surveyors have cited existing conditions that did not meet the more restrictive current edition of the FGI Guidelines. Even in the preface to the current FGI Guidelines, it states that their standards only apply to new construction and renovation, and is not retroactive to existing conditions. CMS has since issued informal communications that the FGI Guidelines only apply to new construction and renovation.

Moving to the Joint Commission standard EC.02.06.05, EP 1, we find that they require compliance with the 2014 FGI Guidelines for new, altered or renovated spaces only; not for existing conditions. HFAP standard 11.07.03 is a repeat of CMS standard §482.41(c)(4) and also references the current edition of the FGI Guidelines. So, it would seem the FGI Guidelines wins by popular affirmation.

When it comes to monitoring, there are differences because the two rooms are not considered to be the same. The Central Supply/Storage is considered a clean room and the Decontam Area is considered a dirty room. If there is an opening between the two rooms, there must be a positive air flow from the clean side to the dirty side.

For new construction:

  • The Sterile Supply/Storage room is required to have a positive air pressure, with a minimum of 4 total air-changes per hour that includes 2 outdoor air changes per hour; and a maximum relative humidity of 60% (no minimum requirements), and a design temperature of 72° – 78° F.
  • The Decontam Area is required to have a negative air pressure, with a minimum of 6 total air-changes per hour that includes 2 outdoor air changes per hour; and there is no maximum or minimum relative humidity required, and a design temperature of 72° – 78° F.

It is important to remember that the current FGI Guidelines are in fact guidelines and not standards. It is very possible that older existing hospitals may not be able to meet these ventilation requirements for new construction. In those cases, it is important to verify what guidelines or standards the ventilation requirements were designed to, and whether or not they are still meeting those original design requirements.

As far as frequency of monitoring… There is not much stated in writing, but Joint Commission seems to expect daily monitoring of air-pressure requirements, which can be easily accomplished through various methods. The least expensive approach is to use a tissue at the bottom of the door to observe whether the air pressure is positive or negative. Other methods utilize inexpensive manual indicators (ball-in-tube, flappers) mounted in the wall near an entrance door, to more elaborate electronic monitoring equipment that would send messages to plant operators when the air pressure is non-compliant.

The air changes per hour rate is much more difficult to monitor, and usually requires manually measuring the air flow at each supply and return/exhaust diffuser with bulky flow-hoods. This is usually done annually, or more often if there have been problems in the past.

Humidity monitoring can be done manually with sling psychrometers; small inexpensive portable battery-operated humidity monitors; or electronic monitoring through the building automation system. The beauty of the building automation system doing the monitoring is it is automatic and there is a record (log) of the measurements; and if there is a reading out of the acceptable range, it automatically notifies the plant operator. The frequency of monitoring temperature and humidity is not stipulated, but it would be reasonable that a surveyor would expect the hospital to have the frequency identified through a risk assessment. I suggest the hospital monitor and log the temperature and humidity daily. Again, it must be documented through a risk assessment to have any validity with a surveyor. If there are other guidelines that recommend more frequent monitoring (such as AORN, AAMI or CDC) then those should be followed.