Fw: Wetted Building Materials Sprout Mold in 48 Hours

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: 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 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@... .

:

:

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