The Dangers of Secondary Mold Growth
Caused by Improper Remediation of Flooded Buildings
Molds and other microbes start growing on water damaged materials within 48 hours after flood waters have receded. Molds can amplify in large numbers behind wall cavities, hidden from view and in other places where moisture remains. These molds can cause health problems, occasionally serious ones. If properly remediated right after the waters recede these health risks can be avoided along with the cost of future remediation. Please see the following paper for details, providing tips and references for proper remediation.
Important Considerations in the Decontamination of Flooded Buildings
As you are aware, the recent floods will continue to have a major impact upon all involved for quite some time. As the waters recede, a major cleanup effort is beginning. The effort to restore homes and businesses back to their original condition will be conducted by various types of individuals ranging from home and business owners to restoration specialists experienced in restoring water damaged structures. The quality and extent of this cleanup will be varied according to the expertise of the individuals and companies involved. These various parties should be following published guidelines established by governmental and non governmental groups. Important guidelines include: the American Red Cross/FEMA (ARC 4477/FEMA 234, 1992) publication "Repairing Your Flooded Home" and the Institute of Inspection, Cleaning and Restoration Certification, "IICRC Standard and Reference Guide for Professional Water Damage Restoration S500-94". After the North Carolina floods in the fall of 1995, the state of North Carolina adopted the IICRC publication S500-94 as their recommended protocols to mitigate flood damaged buildings. Other publications do exist but these two are essential to have.
Consequences of Improper Remediation
Molds and other microbes can start to grow on water damaged materials in a few days after flood waters have receded. It is well documented that mold contamination in buildings can cause significant health problems. These problems can include simple allergic responses such as eye, nose and throat irritation, excessive colds and flu, lowered immune systems, acute mycotoxicosis, a severe reaction to mold produced toxic chemicals, mold induced asthma, mold lung infections like aspergillosis, and chronic debilitating lung diseases such hypersensitivity pneumonitis. Recent published research after the Mississippi flood of 1993 stated "that simply cleaning, disinfecting, and drying flooded surfaces may not prevent mold contamination from persisting long after floodwaters have subsided" (Pearce, et., al, 1995). In the houses tested, in this report it was found that wall cavities behind water damaged drywall were not opened or treated. Only the drywall was dried and disinfected. Secondary contamination from mold growth was able to occur and this led to elevated mold spore levels within these structures. Also, the crawl spaces and basements remained a source of elevated relative humidity. Improper decontamination of flooded buildings can pose health problems due to secondary mold growth that becomes established in areas that are not remediated. These established colonies can cause health problems which could continue to effect the building occupants for months and years to come.
It is essential that the decontamination efforts be conducted following the procedures established in the above mentioned publications. Deviation from these procedures will increase the risk of health problems in the future. Some of the important points mentioned in these guidelines and the research regarding drying and decontamination of flooded structures are as follows:
- Flooded river water can be contaminated with numerous microorganisms that pose a threat to health and safety. Flooded waters may contain raw sewage and other contaminants. Microorganisms from contaminated waters can cause a host of illnesses including gastroenteritis, dermatitis, hepatitis A, and cold and flu like symptoms. Safety precautions such as wearing protective gloves, boots, protective headgear and a respirator should be taken by all parties coming in contact with this water and water damaged materials.
- All water-soaked flooring materials such as carpet and carpet pads, inexpensive area rugs, underlayment materials and warped or damaged wood flooring, need to be removed and replaced. All wall coverings, and drywall that have been water damaged need to be removed and the interior wall cavities need to be dried and disinfected. Moisture laden drywall, insulation and lath and plaster that is wet from capillary action needs to be replaced. Wood paneling if not warped or stained may be salvageable. Salvage efforts would require removal, disinfection and sealing of the paneling and thorough treatment of all structural materials behind the paneling before reinstallation.
- Personal contents: All waterlogged porous fabrics such as pillows, mattresses, stuffed animals, upholstered furniture need to be discarded. Fabrics such as bedding, linens, clothing may be laundered or professionally dry-cleaned. Books, papers, documents and photographs of personal value can be salvaged. Consult with a professional restorer specializing in document disinfection, drying and preservation techniques.
- Crawl spaces and basements need to be dried out and plastic barriers should be put down on the ground to lower relative humidity. All openings from the crawl space/basement into the upper part of the house such as wiring runs and plumbing chases need to be sealed with plumbers foam or equivalent.
- The heating, ventilation and air conditioning (HVAC) system needs to be cleaned out, disinfected or in the event of contamination or inaccessibility, replaced. The cold air return plenum, if water damaged, needs to be thoroughly inspected, porous materials removed, the area disinfected and dried before returning the HVAC system to service. Water damaged ducting needs to be replaced. Submerged gas and oil appliances will need replacement.
- Areas with difficult access such as attics and crawl spaces should not be overlooked and should be remediated if water damaged. Water damaged inaccessible areas can become reservoirs of microbial growth.
- All structures occupied by high risk individuals should be evaluated by an environmental consultant experienced with water damaged buildings and microbial contamination issues. These high risk individuals include the infirm elderly with compromised immune systems, immune compromised AIDS and cancer patients, individuals recovering from surgery or extended illness, the presence of young children, especially infants under the age of two, and individuals with respiratory problems. An environmental consultant can test the structure and advise on proper remediation procedures to insure that the structure is clear of contamination before reoccupancy.
- When seeking assistance from professional restoration firms, ask for affiliation with industry trade associations such as the Water Loss Institute, (WLI) a division of the Association of Specialists in Cleaning and Restoration (ASCR International) and water damage technicians who have been certified and registered with the IICRC. These individuals have been trained and tested on the remedial procedures as referenced in this paper.
Following the above guidelines and the publications referenced will go a long way in protecting the health and safety of all individuals involved with these unfortunate floods.
This paper was written by R. David Bierman, REA a state Registered Environmental Assessor, who has 10 years experience conducting microbial investigations of water damaged buildings. He is also an educator to the restoration and insurance industry on proper remediation of mold and sewage contaminated structures. He was a contributor to the IICRC Standard and Reference guide S500-94. He is the owner of Safe Environments in Novato, CA, and an associate of Restoration Consultants in Sacramento, CA, two firms specializing in consulting, environmental monitoring and project management of contaminated water intrusions into buildings.
Sources for the above publications:
"Repairing Your Flooded Home" ARC #4477/FEMA 234 contact: the local American Red Cross or the local US Governmental Office of the Federal Emergency Management Agency.
"IICRC Standard and Reference Guide for Professional Water Damage Restoration S500-94" contact: IICRC, 360-693-5675 or Restoration Consultants, 916-736-1100.
For computerized IICRC registrant referral directory call: 1-800-835-4624,
For information on Water Loss Institute members in northern and central California call ASCR headquarters at: 1-800-272-7012, or visit their web site at: http://www.ascr.org.
Berry, M., et. al., Suggested Guidelines for Remediation of Damage from Sewage Backflow into Buildings, Journal of Environmental Health, October, 1994.
Berry, M., et. al., Protecting the Built Environment - Cleaning for Health, 21st Press, Chapel Hill, NC, 1993.
Burge, H.A., "Approaches to the Control of Indoor Microbial Contamination." In: Proceedings of IAQ 87, Practical Control of Indoor Air Problems, Atlanta: ASHRAE, Inc., 1987.
Morey, P., "Guidelines and Specifications for Remediation", 10th Annual Professional Conference on Industrial Hygiene, American Industrial Hygiene Association Conference, San Diego, CA, 1995.
New York City Department of Health, "Guidelines on Assessment and Remediation of Stachybotrys chartarum in Indoor Environments" sponsored by NYC Dept. of Health, NYC Human Resources Administration and Mount Sinai Occupational Health Center, 1993.
Pearce, M., et al., "Long Term Monitoring of Mold Contamination in Flooded Homes", Environmental Health Oct. 1995.