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Fire & Water - Cleanup & Restoration

Mold Growth, Assessment, and Remediation

9/21/2016 (Permalink)

Hidden mold

Mold is detectable by smell and signs of water damage on walls or ceiling, and can grow in places invisible to the human eye. It may be found behind wallpaper or paneling, on the inside of ceiling tiles, the back of drywall, or the underside of carpets or carpet padding. Piping in walls may also be a source of mold, since they may leak (causing moisture and condensation).[8]

Spores need three things to grow into mold:

  • Nutrients: Cellulose (the cell wall of green plants) is a common food for indoor spores.
  • Moisture: To begin the decaying process caused by mold
  • Time: Mold growth begins from 24 hours to 10 days after the provision of growing conditions.

Mold colonies can grow inside buildings, and the chief hazard is the inhalation of mycotoxins. After a flood or major leak, mycotoxin levels are higher even after a building has dried out.[7]

Food sources for mold in buildings include cellulose-based materials such as wood, cardboard and the paper facing on drywall and organic matter such as soap, fabrics and dust-containing skin cells. If a house has mold, the moisture may originate in the basement or crawl space, a leaking roof or a leak in plumbing pipes. Insufficient ventilation may accelerate moisture buildup. Visible mold colonies may form where ventilation is poorest and on perimeter walls (because they are nearest the dew point).

If there are mold problems in a house only during certain times of the year, the house is probably too airtight or too drafty. Mold problems occur in airtight homes more frequently in the warmer months (when humidity is high inside the house, and moisture is trapped), and occur in drafty homes more frequently in the colder months (when warm air escapes from the living area and condenses). If a house is artificially humidified during the winter, this can create conditions favorable to mold. Moving air may prevent mold from growing, since it has the same desiccating effect as low humidity. Molds grow best in warm temperatures, 77 to 86 °F (25 to 30 °C), although growth may occur between 32 and 95 °F (0 and 35 °C).[9]

Removing one of the three requirements for mold reduces (or eliminates) new mold growth:

  • Moisture
  • Food for the mold spores (for example, dust or dander)
  • Warmth; mold generally does not grow in cold environments.

HVAC systems can produce all three requirements for mold growth. The air conditioning system creates a difference in temperature, encouraging condensation. The high rate of dusty air movement through an HVAC system may furnish ample food for mold. Since the air-conditioning system is not always running, warm conditions are the final component for mold growth.


    Jump up ^ Indoor Environmental Quality Dampness and Mold in Buildings. National Institute for Occupational Safety and Health. August 1, 2008.Jump up ^ Minnesota Department of Health. "Mold and Moisture in Homes". Minnesota North Star. Retrieved 22 November 2011. Jump up ^ Gent, Janneane. "Levels of Household Mold Associated with Respiratory Symptoms in the First Year of Life in a Cohort at Risk for Asthma" (PDF). Department of Epidemiology and Public Health, Yale University. Retrieved 18 November 2011. Jump up ^ Cohen, Aaron. "WHO Guidelines for Indoor Air Quality: Dampness and Mould" (PDF). World Health Organization. Retrieved 18 November 2011. Jump up ^ "Warm Air is a Moisture Conduit". by Robert Wewer. FSI Restorations. Retrieved 1 January 2014. Jump up ^ "The Doormat Test". by Robert Wewer. FSI Restorations. Retrieved 1 January 2014. ^ Jump up to: a b Canada Mortgage and Housing Corporation^ Jump up to: a b c d e "A Brief Guide to Mold, Moisture, and Your Home. EPA 402-K-02-003". U. S. Environmental Protection Agency. September 2010. Retrieved 10 May 2013. Jump up ^ "Controlling Mold Growth in the Home" (PDF). Kansas State University. Jump up ^ Niemeier, R. Todd, Sivasubramani, Satheesh K., Reponen, Tiina and Grinshpun, Sergey A., (2006) "Assessment of Fungal Contamination in Moldy Homes: Comparison of Different Methods", Journal of Occupational and Environmental Hygiene, 3:5, 262-273 [1]Jump up ^ "Mold Resources". United States Environmental Agency. Archived from the original on February 18, 2004. Retrieved July 12, 2015. Jump up ^ "List A: Antimicrobial Products Registered with the EPA as Sterilizers" (PDF). US Environmental Protection Agency Office of Pesticide Programs. February 2014. Retrieved July 12, 2015.  |archive-url= is malformed: flag (help)Jump up ^ "Mold Cleanup & Abatement, Removal Service Company - Victoria, BC". Retrieved 2016-07-06. ^ Jump up to: a b "Guidelines on Assessment and Remediation of Fungi in Indoor Environments" (PDF). New York City Department of Health and Mental Hygiene. November 2008. Retrieved 10 May 2013. Jump up ^ NIOSH. "Recommendations for the cleaning and remediation of flood-contaminated hvac system: A guide for building ovwners and managers". Center For Disease Control. Retrieved 18 November 2011. Jump up ^ "Chapter 6 - Containment and Personal Protective Equipment (PPE)". EPA. Retrieved 29 June 2014. Jump up ^ "Mold Removal Protection Levels". Environmental Protective Solutions. Retrieved 29 June 2014.

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