American Conference of Governmental Industrial Hygienists (ACGIH^®)

Remediation of Microbial Contamination

Chapter 15

Richard J. Shaughnessy and Philip R. Morey

Excerpted section for the HVAC  

Highlighted areas added for emphasis

15.3     HVAC System Remediation

The guidelines outlined in Table 15.1 can be applied to remediation of microbial growth on surfaces in HVAC systems.  Application of biocides as a substitute for removing microbial growth and settled biological material is not considered acceptable.  In the first place most disinfectants and sanitizers are approved for use on previously cleaned rather than soiled surfaces[see 16.2.4].  Secondly, the allergenicity and toxicity of biological materials is not related to microorganism viability (Morey, 1994; ISIAQ, 1996).  Contaminated porous materials in HVAC systems must be removed to the bare (underlying) metal and the contaminated materials appropriately discarded.  Full-containment procedures should be implemented when removing extensive areas of contaminated porous materials from large HVAC system components (e.g., air handling plenums) (Morey, 1994).  Depending on the extent of visible fungal contamination, removal of porous materials from smaller HVAC system components (e.g., unit ventilators and fan coil units) requires source or local containment precautions supplemented by HEPA vacuum cleaning. 

            HVAC system cleaning and decontamination to remove dust and biological growth has expanded into a large industry serving both residential and commercial building markets (Burge, 1995; NADCA, 1992, 1997).  The USEPA has a document on duct cleaning which is available in print or from their website (www.epa.gov/iaq/airduct.html) (USEPA, 1998).  Although written for homeowners, much of the information

author

Richard J. Shaughnessy, Ph.D., received his Ph.D. in Chemical Engineering from the University of Tulsa where he currently serves as the Program Manager for indoor air research and is the University spokesman on issues related to IAQ or radon. He has taught and conducted research abroad in locations including Singapore, China, South Africa and Australia, and is recipient of the 1996 Trainer of the Year Award. He has published extensively on indoor air with respect to his research and studies. He served as the principal advisor to the EPA on development of the IAQ Diagnostics: Hands-On Assessment of Building Ventilation and Pollutant Transport course, and has been delivering IAQ courses for the EPA since 1991.

Bioaerosols: Assessment and Control was written by the ACGIH^® Bioaerosols Committee

© 2002 American Conference of Governmental Industrial Hygienists, 1330 Kemper Meadow Drive, Cincinnati, Ohio 45240