After the Storm - Now What?
During a flood cleanup, the indoor air quality in homes, offices or any type of building may at first glance be the last thing on anyone's mind, but failure to completely and properly dry building interiors and remove any and all contaminated materials can result in serious long-term health risks to building occupants.
Standing water and wet materials are a breeding ground for microorganisms, including bacteria and mold. They can trigger allergic reactions or make asthma symptoms worse, and continue to damage building materials, furnishings long after the flood.
Safety is the first concern when entering a home or building that has been damaged by floodwaters. Here are some guidelines:
Check for structural damage. Do not go in if there is any chance of the building collapsing.
Upon entering the building, do not use matches, cigarette lighters or any other open flames, since natural gas and other combustible fumes may be trapped inside. Instead, use a flashlight.
Be careful walking around. After a flood, steps and floors are often slippery with mud and covered with debris, including nails and broken glass.
Keep the electrical power off until an electrician has inspected the electrical system for safety.
Until local authorities proclaim the water supply to be safe, boil water for drinking and food preparation vigorously for five minutes before using.
Next Priority -- Drying Out
Once the building has been judged structurally sound, the next priority is to dry it out!
Many microorganisms, including mold begin growing within 24 to 48 hours. As a result, it is imperative to begin the drying process as soon as possible. Here are some steps to follow:
Remove standing water
Identify and remove animal carcasses and materials affected by the water
Dry out the area
Wear protective clothing
Clean and disinfect
Hire professional help
Remove Any Standing Water
Standing water is a breeding ground for microorganisms, which can become airborne and be inhaled. In addition, floodwater that contains sewage or decaying animal carcasses may also harbor infectious microorganisms. To minimize health problems and lessen structural damage, all standing water should be removed as quickly as possible.
Identify and Remove Animal Carcasses and Materials Affected by the Water
If a flood involves sewage-contaminated water or has animal carcasses floating in it, do not try to save any of the materials as exposure to this kind of water carries the additional hazard of infection with the hepatitis A virus.
Bag and throw away any materials that can trap mold. Also, make sure that there is no asbestos or lead in the materials to be thrown out. Disturbing or removing materials containing asbestos (such as in insulation) or lead (such as in lead-based paint) may result in elevated concentrations of those hazardous materials in the air. Just looking will not yield a definitive answer. Sampling may need to be done to verify the materials' composition.
Some materials tend to absorb and keep water more than others. If these materials get wet and cannot be thoroughly cleaned and dried, discard them. Otherwise, they can remain a source of future microbial growth. Mold may begin growing 24 hours after the materials become wet although there may not be any visible signs of it. Molds are mistakenly considered more of a nuisance than a health threat, but their damage can be long lasting. Examples of water-absorbing materials that must be removed and thrown out include:
These items can retain water and begin growing mold even if they appear to be dry. Some may become contaminated with mold while wet and continue to be a source of mold spores and exposure even after drying. Flooded carpet, for example, can store mold spores for years. Any carpet if not properly maintained can store mold spores, and flooded carpet allows the mold to grow further. Running fans and opening windows is not enough. Once carpet becomes colonized (mold growing in the material), it needs to be discarded unless professional cleaning can effectively remove the microbiological contaminants.
Remove all drywall and insulation damaged by water at least 12 inches above the high water mark. Visually inspect the wall interior and remove any other materials with visible mold growth. (This step may have to be carried out by a licensed contractor.) This removal of mold-contaminated material from the walls is crucial because both allergic and toxic effects can remain in dead spores.
Dry Out the Area
If areas are wet, yet have not suffered from a flood, set up fans and turn on the HVAC system to help dry things out. It is important to do this because microorganisms like mold can quickly begin growing in materials. These can later be released into the air and trigger allergies and asthma attacks along with other health problems. If humidity levels are increased for a long time then dust mites may grow. Dust mites prefer humidity levels above 60 percent.
Be patient! The proper drying out process can take a long time.
In large buildings, the typical drying out period may be 7 to 10 days. It is imperative to not only dry the building, but to dry it out correctly. Drying out large buildings is a very complex process and will require the help of professionals. Believe it or not, if a building is dried out too quickly, interior furnishing materials can become damaged.
If the structure does not have electricity, do not use internal combustion engines indoors since they can quickly emit deadly levels of carbon monoxide. Examples include gasoline-powered generators, camp stoves and lanterns, or charcoal-burning devices. Do not use combustion devices designed for outdoor use inside, even in an emergency, since that can be deadly!
Dress the Part
Because mold may have begun growing in some of the materials that will be removed, be sure to wear appropriate protective clothing. Cleaning up mold can be hazardous to health since mold counts are typically 10 to 1,000 times higher than background levels during the cleaning of mold damaged materials. Here are some steps to follow:
Wear a dust mask or particulate respirator (sometimes referred to as a N95 or TC-21C particulate respirator) to keep from breathing in airborne spores. However, remember this type of mask will not protect the persion wearing it from the vapors of cleaning or bleach solutions that can irritate eyes, nose, and throat, and damage clothing and shoes. In addition to protective equipment, make sure the working area is ventilated well.
Wear gloves. While removing materials, cover rubber gloves that may tear easily with work gloves. Be sure to wear gloves when using cleaning and disinfecting solutions.
Wear sturdy waterproof boots to protect the feet from hazards, which may not visible in dirty floodwater.
Wear protective clothing that is easily cleaned or discarded
Clean and Disinfect
All surfaces that are exposed to food, children or pets will need to be thoroughly cleaned. Also clean and disinfect non-porous materials such as glass, plastic or metal. Materials such as the tops of metal desks or file cabinets and concrete, cement, or tile floors can be cleaned using a solution of one (1) part bleach to 10 parts water. Be sure the area is well ventilated.
Ask staff or bystanders to leave when these areas are being cleaned.
Before beginning to clean off any mold, try cleaning a small test patch of it first. If you feel that this adversely affected your health, you should consider paying a licensed contractor or professional to carry out the work.
Use soap/detergent and hot water or a commercial cleaner. DO NOT APPLY ANY AMMONIA-BASED PRODUCTS! Ammonia or ammonia-based cleaners should not be used since residual ammonia can encourage mold growth.
Thoroughly scrub all contaminated surfaces (use a stiff brush to clean block walls) with an excessive amount of soap/detergent.
Rinse well with water
After thorough cleaning and rinsing, disinfect the area. To disinfect, use a solution of 10 percent household bleach (for example, one (1) cup bleach per five (5) gallons of water) and a little detergent. (The detergent will help with the dirt and oil on the surface and act as a surfactant to help thoroughly wet all surfaces). NEVER MIX BLEACH AND AMMONIA SINCE THEY CAN FORM DEADLY VAPORS!
Bleach solution should be applied with a handheld garden sprayer. For large exterior areas, you can spray using a garden hose and nozzle but avoid excessive amount of runoff or standing bleach.
When disinfecting a large structure, make sure the entire surface is wetted (floors, joists and posts). Use a brush or broom to force the solution into crevices.
Be sure you wash and disinfect the walls, floors, closets, shelves and contents. The heating, ventilating and air-conditioning (HVAC) system should be evaluated for mold contamination and professional help engaged to handle the evaluation and cleaning of the system.
Work over short time spans and rest in a fresh air location. Provide continuous and controlled ventilation in work area, with the area of contamination kept at a negative pressure in relationship with the rest of the home. Iin other words, air should flow from clean to dirty areas.
Allow bleach solution to dry naturally for a six to eight hours.
Air out the house (and the building if windows can be opened) out for about two to three days after the work. Increase airflow in the house by moving furniture away from walls and opening closet doors. Consider increasing outdoor airflow in buildings in which windows cannot be opened.
Hire Professional Help
Most mold remediation guidelines advise that if the area of mold growth is larger than 10 sq. ft. to hire a professional contractor to remove the mold and any contaminated materials. But be careful! After a major storm, unqualified opportunists may offer to help. Be wary of people who drive through neighborhoods offering help in cleaning up or repairs. Be sure that any contractors that are hired for cleanup or repairs are qualified to do the job. Check their credentials and their references. Insurance adjusters may be able to assist in finding reputable and qualified contractors.
For More Information
Fact Sheet: Flood Cleanup - Avoiding Indoor Air Quality Problems. US Environmental Protection Agency. Office of Radiation and Indoor Air (6607J). August 1993, 402-F-93-005.
Surviving the Storm: A Guide to Hurricane Preparedness. US Department of Homeland Security/Federal Emergency Management Agency.