Indoor Air and Infection Control

January 15, 1996

Those of us who have had any significant interactions with hospitals or other healthcare facilities have probably participated in some conversations about Tuberculosis (TB) and the need to protect persons in the healthcare professions from TB. This is because, in the past several years, TB, which was once thought to be virtually defeated, has reemerged as a major health problem. TB was once thought to be transmitted only through person to person contact but now it is believed that it can be deposited on environmental surfaces and later picked up by someone coming in contact with that surface. There are some experts who suspect that it is possible for the microorganism that cause TB to be drawn into the air-conditioning system and carried to persons throughout a facility.

The Bloodborne Pathogens Rule

This standard (29 CFR 1910.1030) was enacted as part of the OSHA regulations in response to the risks associated with TB, AIDS (HIV), and other infection risks in the workplace. Although the new rule applies to all workplaces, it is logical that facilities catering to sick people are at the greatest risk. Therefore they tend to both be more knowledgeable of the regulations and more concerned about protecting their facilities from these risks. At any rate, indoor air is logically a potential source of contamination that could spread infection, therefore, as professionals promoting improved indoor air quality, we should be knowledgeable of the portions of the rule that might impact us.

Actually, indoor air quality is not addressed in any way in the standard. The closest that the text comes is in paragraph (d)(4)(Housekeeping) that states, in part, ‘Employers shall ensure that the worksite is maintained in a clean and sanitary condition. The employer shall determine and implement an appropriate written schedule for cleaning and method of decontamination based upon the location within the facility, type of surface to be cleaned, type of soil present, and tasks or procedures being performed in the area.’ ‘Decontamination’ is a term we relate readily to in conjunction with cleaning air conveyance systems. We may, however, be somewhat confused by the definition of the word contained in the rule. ‘Decontamination means the use of physical or chemical means to remove, inactivate, or destroy Bloodborne pathogens on a surface or item to the point where they are no longer capable of transmitting infectious particles …’ After all, we are interested in a wide spectrum of contaminates, not just Bloodborne pathogens.

At the time the CDC guidelines for infection control, on which the rule is based, were written, poor indoor air quality was not a widely recognized problem. It is safe to assume, therefore, that the framers of the rule did not consider indoor air as a likely vector for the spread of infection. This is not to say they rejected the possibility, it just did not appear to be part of their thinking. This is somewhat confirmed in that the guidelines for enforcement of the rule (CPL 2-2.44C) do not include any reference to the air conditioning system. The Housekeeping section addresses only patient contact surfaces and medical equipment and devices. In fact, the only reference that even addresses facility equipment in any manner is a discussion in Appendix C which discusses the use of Biological Safety Cabinets in laboratories. These are very specialized devices and you should not attempt to clean them or work on them in any way unless you have special training and certification for such activities.

So why do facility managers want to know if our procedures are effective against TB? That comes from the Housekeeping section of the OSHA enforcement guidelines (CPL 2-2.44C) where the inspector is advised to check to see that chemicals that are used to disinfect medical equipment are effective against TB. Unfortunately, disinfection of medical devices and the sanitizing you will do in the air conditioning system are very different. Although many do not realize it, the terms ‘Sanitize’, ‘Disinfect’, and ‘Sterilize’ apply to different levels of cleanliness and have very specific meanings that were developed years ago by a researcher named Spaulding. Achieving the level known as ‘Disinfection’ requires that virtually all of the microorganisms on a surface be killed or inactivated. This level is not practical in the complex environment that exists inside an air conditioning system. What we are attempting to achieve is ‘Sanitation’ which means that the population of organisms is greatly reduced.

Because of this fact, the EPA does not register products intended for use in air-conditioning systems as ‘Disinfectants’. In addition a product registered as a ‘Sanitizer’ will not be allowed to claim efficacy against TB. Therefore, any discussion about eliminating TB from the air-conditioning system is pointless. Unfortunately, the infection control personnel in a hospital may not be aware of the above. If you find yourself in the middle of such a discussion, you may need to involve someone who is knowledgeable of federal regulations, indoor air quality, and infection control. That is where our technical support staff can be of real value and we are as close as the nearest phone. 800/889-2251.

Reality is Stranger Than Fiction

Ranked in difficulty from hardest to kill or inactivate to easiest, most experts consider TB the most difficult, followed by Hepatitis B(HBV) with HIV very easy. In spite of this, a group of scientists are currently urging OSHA to change the requirement for an appropriate disinfectant to use in complying with the Bloodborne pathogens rule form one being effective against TB to one effective against HIV. Why is this? The answer is that tests used to test for effectiveness against TB are very unreliable, no tests have been approved for HBV, and the HIV test is available and reliable. Therefore they would rather see a easy standard that is reliable than a difficult standard that is highly unreliable. This reminds us that Microbiology is often as much an are as a science.

Bob Baker is a member of ASHRAE and Chairman and CEO of BBJ Environmental Solutions, Inc., a manufacturing company specializing in providing clean air through environmentally responsible products.