[GBlist] Mold (IAQ)

[Chris Koehn <chris@koehn.com>]

Title: Mold (IAQ)

INTERESTING STUDY ON MOLD GROWTH AND INDOOR AIR QUALITY:

> Subject: Wetted Building Materials Sprout Mold in 48 Hours
> 
> 
> Welcome to CutterEdge Buildings, the weekly e-mail service
> from Cutter Information Corp.
> 
> 
> WETTED BUILDING MATERIALS SPROUT MOLD
> IN 48 HOURS EVEN AT LOW RELATIVE HUMIDITY
> 
> It is widely accepted that to avoid mold growth on cellulose-
> based building materials that become wet, they must be dried within
> 48 hours.  Mold's purpose in nature is to digest wood and, by
> extension, paper products.  People usually refer to this digestion
> as rot or decay.  Since contractors widely use gypsum covered
> by a sheathing of paper cardboard and other cellulose products
> (including ceiling tiles in modern building construction), leaks,
> high RH, and condensation can readily promote the growth of
> mold, which is omnipresent indoors and outdoors.
> 
> Unfortunately, when a leak promotes mold contamination, the mold
> species that tend to proliferate indoors often produce toxins
> that make people ill.  Indoor environmental quality professionals
> and others know that building materials must be dried quickly
> to head off potentially serious mold contamination.  But how quickly
> must that drying be done, and how low must the RH be to stymie
> mold growth?
> 
> Researchers Elliott Horner, Phil Morey, and Bryan Ligman report
> that mold colonies grew on water-damaged materials within 48-72 hours
> even at 44%-45% relative humidity (RH), though growth was slower.
> Interestingly, the researchers report that tiny pits in acoustical
> ceiling tiles were the sites of some of the earliest mold growth
> following water damage.
> 
> The researchers work for Air Quality Sciences, Inc. of Atlanta,
> Georgia.  Horner, Ph.D., is director of the firm's microbial
> laboratory; Morey, Ph.D., CIH, is vice president of microbiology
> and indoor air quality (IAQ); and Ligman is a manager for building
> investigations.  Horner presented the research team's findings
> at *IAQ 2001, Moisture, Microbes and Health Effects: Indoor Air
> Quality and Moisture in Buildings* in San Francisco, California,
> in November 2001.  The conference was organized and sponsored
> by the American Society of Heating, Refrigerating and Air-Conditioning
> Engineers (ASHRAE).  Their paper is entitled "How Quickly Must
> Gypsum Board and Ceiling Tile Be Dried to Preclude Mold Growth
> After a Water Accident?"
> 
> At *IAQ 2001*, Horner said the next steps for researchers include
> confirming the team's findings in a dynamic chamber, determining the
> RH% drop needed to stop mold growth, and assessing whether use
> of a biocide would "buy an extra day" to dry out building materials.
> In response to a question about what the findings mean for real
> buildings, Horner said that water from a pipe that bursts on an
> upper floor would collect resident mold spores as it drains.  Such
> water moving down through floors, ceilings, and walls "would be
> loaded with spores," he told attendees.
> 
> For more information, contact Elliott Horner, Ph.D., Microbial
> Laboratory, Air Quality Sciences, Inc., 1337 Capital Circle,
> Atlanta, GA 30067, USA.  Tel: +1 770 933 0638;
> Fax: +1 770 933 0641; E-mail: ehorner@aqs.com .