Avoiding and Remediating Mold

Flood events remind us of the importance of having a plan for mold.

By Alexandra Walsh

With so many businesses inundated by floodwaters in Texas and Florida as a result of Hurricanes Harvey and Irma, it’s a good idea to revisit what mold is and what to do about it.

During a flooding event, there is an increased danger of contracting bacterial, viral, and protozoal diseases. Floodwaters can be contaminated with sewage and decaying animal and human remains. Therefore, disinfection of contaminated hands, clothing, tools and equipment, and surfaces in work areas is critical in preventing disease.

Mold can cause any number of health effects and symptoms, including allergic reactions. Preventing mold growth and taking measures designed to protect the health of home occupants and workers is an important responsibility for business owners, as is the health and safety of workers designated to prevent and clean up mold.

With guidance, business owners with little or no experience with mold remediation may be able to reasonably judge whether mold contamination can be managed in-house or whether outside assistance is required.

What is mold and why is it hazardous?

Mold, also known as mildew, is a form of fungus present year-round. Most molds reproduce by forming spores that are released into the air. When spores land on a suitable moist surface they begin to grow, penetrate porous materials, and release chemicals.

Everyone is exposed every day to fungal spores in the air we breathe. Mold growth is encouraged by warm and humid conditions, although it can grow during cold weather too.

Just as there is no such thing as a completely clean home or building, almost all structures have some mold. Humidity, dampness, roof leaks, plumbing leaks, and faulty sprinkler systems can all lead to mold.

Most molds are harmless but some can cause infections and allergy symptoms, and produce toxins. Infections are rare in healthy individuals and the effect of toxins is still not well understood. Nonetheless, mold remediation is often necessary to return impacted spaces to a safe condition and make them suitable for occupancy.

People with special health concerns should consult their doctor if they are concerned about mold exposure. Symptoms that may seem to occur from mold exposure may be due to other causes, such as bacterial or viral infections or other allergies.

Mold cleanup plan

The most important requirement is to control the source of moisture. Next, survey the types of materials and the size of the area involved. This may become important in determining the strategy for remediation and protecting workers.

Materials and tools that cannot be dried and fully cleaned should be removed, using methods minimizing exposure to spores. Mold remediation often involves construction activities.

Drying can involve the use of fans, blowers, and dehumidifiers. However, the more humid the air, the less effective the blowers will be. It is often more cost-effective to remove and replace the building materials than it is to dry and clean materials contaminated with mold.

Remediating mold

Contaminated clothing, tools, and equipment should be cleaned. It is preferable to use soap and clean water whenever available. When clean water is not available, use a solution of one quarter cup of bleach to one gallon of water.

  • Immerse objects in the solution for 10 minutes.
  • If clothing, gently swirl every few minutes.
  • If tools or equipment, allow them to drain and transfer directly to the bleach solution used for cleaning hands.
  • Reimmerse the clothing in the household bleach solution for 10 minutes with periodic gentle swirling of the clothing.
  • If clothing, wring out as much moisture as possible.
  • Allow clothes to thoroughly dry before wearing.

Some mold problems are beyond the ability of business owners to deal with. The Occupational Safety and Health Administration has guidelines to help business owners know when professional help is needed.

If the damage is at a commercial property, remediation can be conducted by the regular building maintenance staff if the mold problem is at Level I or Level 2.

Level 1 is considered small isolated areas of 10 square feet or less, such as mold on ceiling tiles and small areas on walls. Level 2 is areas with up to 10 to 30 feet of mold, such as on individual wallboard panels.

The staff should be trained on proper cleanup methods, personal protection, and potential health hazards. This training can be performed as part of a program to comply with the requirements of the OSHA Hazard Communication Standard (29 CFR 1910.1200).

Respiratory protection such as an N-95 disposable respirator is recommended and gloves and eye protection should be worn. The work area should be unoccupied. Removing people from spaces adjacent to the work area is only recommended for persons recovering from recent surgery, immune-suppressed people, or people with chronic inflammatory lung diseases such as asthma, hypersensitivity pneumonitis, and severe allergies.

DACUM Codes
To help meet your professional needs, this column covers skills and competencies found in DACUM charts for drillers and pump installers. DO refers to the drilling chart and PI represents the pumps chart. The letter and number immediately following is the skill on the chart covered by the column. This column covers: DOK-6, DOK-9, PIG-3, GOI-6, GOI-9. More information on DACUM and the charts are available at www.NGWA.org/Certification and click on “Exam Information.”

While it is not necessary to seal off the area being worked on, it is helpful to follow dust suppression methods such as misting (not soaking) surfaces prior to cleaning.

Mold can generally be removed from nonporous surfaces by wiping or scrubbing with water and detergent. It is important to dry these surfaces quickly and thoroughly to discourage further mold growth.

There are certainly more exotic cleaners that can be used such as ammonium chloride solutions, phenols, and strong disinfectants—but sometimes this may be overkill and if not properly used, vapors from some of these solutions can be more harmful than the mold.

As a general rule, simply killing the mold, for example with biocide, is not enough. The mold must be removed since the chemicals and proteins which can cause a reaction in humans are present—even in dead mold.

The use of a disinfectant, such as chlorine bleach, is not recommended as a routine practice for remediating mold, though there may be instances where professional judgment may indicate its use.

Contaminated materials that cannot be cleaned should be removed from the building in a sealed plastic bag and disposed of as ordinary waste. The work area as well as those areas the workers are using to exit and enter should be cleaned with a damp cloth or mop and a detergent solution.

Level 2 areas should also be swept with an HEPA (highefficiency particulate air) vacuum cleaner. All areas should be left dry and visibly free from contamination and debris.

When the problem gets too big

If the mold problem exceeds Level 1 and 2 (covers more than 30 feet), a professional water damage remediation company
should be called in.

It’s a good idea to consult with industrial hygienists or other environmental health and safety professionals with experience performing microbial investigations prior to mold remediation to provide oversight for the project.

A professional remediation firm will know at the outset if the job is big enough to warrant calling in an industrial hygienist. These experts can also develop specific guidelines prior to soliciting proposals from remediation companies, or recommend a remediation plan for the outside company to follow. Some insurance companies require this in order to process water damage claims.

The remediation should begin within 24 hours to extract the water and start the drying process—as mold will begin to grow within 24 to 72 hours. That process is accelerated if the environment is warm. Structural drying can take seven to 14 days.

Once the cleaning is complete, the remediation company or the industrial hygienist overseeing the remediation should do a follow-up visual inspection and a moisture survey using an infrared camera or moisture-measuring gauge to make sure all materials are dry (less than 15% moisture).

Preventing mold

Controlling excess moisture is the key to preventing and stopping indoor mold growth.

  • Repair plumbing leaks and leaks in the building structure as soon as possible.
  • Look for condensation and wet spots. Fix sources of moisture incursion problems as soon as possible.
  • Prevent moisture from condensing by increasing surface temperature or reducing the moisture level in the air (humidity). To increase surface temperature, insulate or increase air circulation. To reduce moisture level, repair leaks and increase ventilation (if outside air is cold and dry) or dehumidify (if outdoor air is warm and humid).
  • Keep HVAC drip pans clean, flowing properly, and unobstructed.
  • Perform regularly scheduled building and HVAC inspections and maintenance, including filter changes.
  • Maintain indoor relative humidity below 60% (25% to 50%, if possible).
  • Vent moisture-generating appliances, such as dryers, to the outside where possible.
  • Vent kitchens and bathrooms according to local code requirements.
  • Clean and dry wet or damp spots as soon as possible, but no longer than 48 hours after discovering.
  • Provide adequate drainage around buildings and slope the ground away from building foundations.
  • Pinpoint areas where leaks have occurred, identify the causes, and take preventive action to ensure they do not reoccur.

Employer responsibility

After the prompt removal of contaminated material and structural repair, the underlying cause of water accumulation must be rectified or mold growth will reoccur. Emphasis should be placed on preventing contamination through proper building and HVAC system maintenance and prompt repair of water-damaged areas.

It is essential employers notify workers or other occupants in the affected area of the presence of mold. Notification should include a description of the remediation and a timetable for completion.

Finally, individuals with persistent health problems that appear to be related to mold exposure should see their physicians for a referral to practitioners who are trained in occupational/ environmental medicine or related specialties and are knowledgeable about these types of exposures.


Alexandra Walsh is the vice president of Association Vision, a Washington, D.C.–area communications company. She has extensive experience in management positions with a range of organizations.

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