Water damage describes various possible losses caused by water intruding where it will enable attack of a material or system by destructive processes such as rotting of wood, mold growth, bacteria growth, rusting of steel, swelling of composite woods, de-laminating of materials such as plywood, etc.

The damage may be imperceptibly slow and minor such as water spots that could eventually mar a surface, or it may be instantaneous and catastrophic such as burst pipes and flooding. However fast it occurs, water damage is a major contributor to loss of property.

An insurance policy may or may not cover the costs associated with water damage and the process of water damage restoration. While a common cause of residential water damage is often the failure of a sump pump, many homeowner’s insurance policies do not cover the associated costs without an addendum which adds to the monthly premium of the policy. Often the verbiage of this addendum is similar to “Sewer and Drain Coverage”.

In the United States, those individuals who are affected by wide-scale flooding may have the ability to apply for government and FEMA grants through the Individual Assistance program.^[1] On a larger level, businesses, cities, and communities can apply to the FEMA Public Assistance program for funds to assist after a large flood. For example, the city of Fond du Lac Wisconsin received $1.2 million FEMA grant after flooding in June 2008. The program allows the city to purchase the water damaged properties, demolish the structures, and turn the former land into public green space.^{[citation needed]}

Water damage describes various possible losses caused by water intruding where it will enable attack of a material or system by destructive processes such as rotting of wood, mold growth, bacteria growth, rusting of steel, swelling of composite woods, de-laminating of materials such as plywood, etc.

The damage may be imperceptibly slow and minor such as water spots that could eventually mar a surface, or it may be instantaneous and catastrophic such as burst pipes and flooding. However fast it occurs, water damage is a major contributor to loss of property.

An insurance policy may or may not cover the costs associated with water damage and the process of water damage restoration. While a common cause of residential water damage is often the failure of a sump pump, many homeowner’s insurance policies do not cover the associated costs without an addendum which adds to the monthly premium of the policy. Often the verbiage of this addendum is similar to “Sewer and Drain Coverage”.

In the United States, those individuals who are affected by wide-scale flooding may have the ability to apply for government and FEMA grants through the Individual Assistance program.^[1] On a larger level, businesses, cities, and communities can apply to the FEMA Public Assistance program for funds to assist after a large flood. For example, the city of Fond du Lac Wisconsin received $1.2 million FEMA grant after flooding in June 2008. The program allows the city to purchase the water damaged properties, demolish the structures, and turn the former land into public green space.^{[citation needed]}

Categories[edit]

There are three basic categories of water damage, based on the level of contamination.

Category 1 Water – Refers to a source of water that does not pose substantial threat to humans and classified as “clean water“. Examples are broken water supply lines, tub or sink overflows or appliance malfunctions that involves water supply lines.

Category 2 Water – Refers to a source of water that contains a significant degree of chemical, biological or physical contaminants and causes discomfort or sickness when consumed or even exposed to. Known as “grey water“. This type carries microorganisms and nutrients of micro-organisms. Examples are toilet bowls with urine (no feces), sump pump failures, seepage due to hydrostatic failure and water discharge from dishwashers or washing machines.

Category 3 Water – Known as “black water” and is grossly unsanitary. This water contains unsanitary agents, harmful bacteria and fungi, causing severe discomfort or sickness. Type 3 category are contaminated water sources that affect the indoor environment. This category includes water sources from sewage, seawater, rising water from rivers or streams, storm surge, ground surface water or standing water. Category 2 Water or Grey Water that is not promptly removed from the structure and or have remained stagnant may be re classified as Category 3 Water. Toilet back flows that originates from beyond the toilet trap is considered black water contamination regardless of visible content or color.^[5]

Classes[edit]

Class of water damage is determined by the probable rate of evaporation based on the type of materials affected, or wet, in the room or space that was flooded. Determining the class of water damage is an important first step, and will determine the amount and type of equipment utilized to dry-down the structure.^[6]

Class 1 – Slow Rate of Evaporation. Affects only a portion of a room. Materials have a low permeance/porosity. Minimum moisture is absorbed by the materials. **IICRC s500 2016 update adds that class 1 be indicated when <5% of the total square footage of a room (ceiling+walls+floor) are affected **

Class 2 – Fast Rate of Evaporation. Water affects the entire room of carpet and cushion. May have wicked up the walls, but not more than 24 inches. **IICRC s500 2016 update adds that class 2 be indicated when 5% to 40% of the total square footage of a room (ceiling+walls+floor) are affected **

Class 3 – Fastest Rate of Evaporation. Water generally comes from overhead, affecting the entire area; walls, ceilings, insulation, carpet, cushion, etc. **IICRC s500 2016 update adds that class 3 be indicated when >40% of the total square footage of a room (ceiling+walls+floor) are affected **

Class 4 – Specialty Drying Situations. Involves materials with a very low permeance/porosity, such as hardwood floors, concrete, crawlspaces, gypcrete, plaster, etc. Drying generally requires very low specific humidity to accomplish drying.

Restoration[edit]

Water damage restoration can be performed by property management teams, building maintenance personnel, or by the homeowners themselves; however, contacting a certified professional water damage restoration specialist is often regarded as the safest way to restore water damaged property. Certified professional water damage restoration specialists utilize psychrometrics to monitor the drying process.^[7]

Standards and regulation[edit]

While there are currently no government regulations in the United States dictating procedures, two certifying bodies, the Institute of Inspection Cleaning and Restoration Certification (IICRC) and the RIA, do recommend standards of care. The current IICRC standard is ANSI/IICRC S500-2015.^[8] It is the collaborative work of the IICRC, SCRT, IEI, IAQA, and NADCA.

Fire and Water Restoration companies are regulated by the appropriate state’s Department of Consumer Affairs – usually the state contractors license board. In California, all Fire and Water Restoration companies must register with the California Contractors State License Board.^[9] Presently, the California Contractors State License Board has no specific classification for “water and fire damage restoration.”

Procedures[edit]

Water damage restoration is often prefaced by a loss assessment and evaluation of affected materials. The damaged area is inspected with water sensing equipment such as probes and other infrared tools in order to determine the source of the damage and possible extent of areas affected. Emergency mitigation services are the first order of business. Controlling the source of water, removal of non-salvageable materials, water extraction and pre-cleaning of impacted materials are all part of the mitigation process. Restoration services would then be rendered to the property in order to dry the structure, stabilize building materials, sanitize any affected or cross-contaminated areas, and deodorize all affected areas and materials. After the labor is completed, water damage equipment including air movers, air scrubbers, dehumidifiers, wood floor drying systems, and sub-floor drying equipment is left in the residence. The goal of the drying process is to stabilize the moisture content of impacted materials below 15%, the generally accepted threshold for microbial amplification. Industry standards state that drying vendors should return at regular time intervals, preferably every twenty-four hours, to monitor the equipment, temperature, humidity, and moisture content of the affected walls and contents.^[5]

The NAU Water Damage Restoration guideline was developed to ensure that all water incursions are handled in a professional manner which includes the latest information / procedures available. Every effort will be made to ensure the health and safety of all NAU faculty, students, staff and visitors to the campus in a timely fashion. Goal Guidelines, procedures and standards have been established not only to ensure the safety of everyone on campus but also to include every means available to promote the preservation, replacement and/or repair of University property according to standards / recommendations contained in the Institute of Inspection Cleaning and Restoration Certification (IICRC) S500 Standard and Reference Guide for Professional Water Damage Restoration. For prolonged water incursion events that lead to the formation of mold growth, remediation efforts shall follow the IICRC Standard for Professional Mold Remediation (S520). Typically an outside contractor that is trained and familiar with the IICRC remediation protocols is retained to perform water, mold and sewage restoration efforts due to the amount of training, vaccination, personal protective equipment (PPE), and other safety requirements associated with the work activities. University personnel that are familiar with water extraction/cleanup activities may assist with small isolated clean water, or Category 1 water, restoration activities if it is safe to do so but should check with their supervisor or NAU Regulatory Compliance. Flood Category Definitions Certain terms and definitions associated with water damage restoration exist. The following are definitions of terms used: Category 1 Water – Water originating from a source that does not pose substantial harm to humans. Category 1 water is also referred to as “clean water.” Examples of clean water sources may include, but are not necessarily limited to the following: • Broken domestic water supply lines; • Tub or sink overflows with no contaminants; • Appliance malfunctions involving domestic water supply lines; • Melting ice or snow; • Falling rainwater; and • Broken toilet tanks and toilet bowls that do not contain contaminants or additives. Clean water that has contact with structural surfaces and content materials may deteriorate in cleanliness as it dissolves or mixes with soils and other contaminants, and as time elapses. Category 2 Water – Water containing a significant degree of chemical, biological and/or physical contamination and having the potential to cause discomfort or sickness if consumed by or exposed to humans. Category 2 water is also referred to as “gray water.” Gray water carries microorganisms and nutrients for microorganisms. Examples of gray water sources may include, but are not necessarily limited to the following: • Discharge from dishwashers or washing machines; • Overflows from toilet bowls with some urine (no feces) • Sump pump failures; • Seepage due to hydrostatic pressure; • Chilled and condensate water; and • Fire Protection Sprinkler Water. Gray water may contain chemicals, biocontaminants (fungal, bacterial, viral algae) and other forms of contamination including physical hazards. Time and temperature aggravate category 2 water contamination levels significantly. Gray water in flooded structures that remains untreated for longer than 48 hours may change to category 3 – black water. Category 3 Water – Grossly unsanitary water containing pathogenic agents, arising form sewage or other contaminated water sources and having the likelihood of causing discomfort or sickness if consumed or exposed to humans. Black water includes sewage and other contaminated water sources entering or affecting the indoor environment. Category 2 water that is not removed promptly from the structure may be reclassified as category 3 water. Toilet back flows that originated beyond the toilet trap are considered black water contamination, regardless of visible content or color. Category 3 water includes, but is not necessarily limited to all forms of flooding from: • Sewage/rainwater mixed; and • Rising water from rivers or streams. Such water sources carry silt and organic matter into structures and create black water conditions. Restoration Guidelines & Criteria Excess Water Removal – Excess water removal is essential as the beginning point of restoration procedures. Removal of excess water may be achieved by physical means such as mopping or soaking up excess moisture from hard surfaces or furnishings. However, water removal usually involves the use of more sophisticated techniques and equipment such as pumps, or specially designed commercial wet vacuuming equipment. Evaporation – Once excess water is removed, remaining water must be changed from a liquid to a vapor by promoting evaporation. Normally, this is accomplished efficiently with specialized air-moving equipment. Dehumidification – Once moisture is evaporated from structural materials and contents into the air, the moisture must be removed from the air through dehumidification, or it must be externally exhausted. Failure to dehumidify may result in substantial secondary damage and present a significant health hazard. Temperature Control – Both evaporation and dehumidification are greatly enhanced by controlling the temperature in a confined environment. Additionally, microorganisms’ growth is temperature related. Thus, temperature modification and control is an important basic principle for safe, effective drying. Monitoring – The damaged structure must be monitored starting with the initial assessment and evaluation, and continuing throughout the restoration process. Monitoring procedures may include, but are not limited to the following: • Temperature and humidity readings; • Updating drying progress status; and • Checking the moisture content of structural wood and other materials with a moisture meter. When applicable, monitoring also must include checking equipment operation, work progress and indoor environment quality. Drying Standards have been developed and are presented in Appendix A. Inspection – Following the removal of excess water, a detailed inspection must be conducted that considers the extent of water migration, the types and quantities of affected materials and the degree of apparent damage. The information obtained may be used to analyze the extent of damage and to determine the job scope. Professional testing equipment and the principals of psychrometry must be used to formulate a plan to dry and restore, or replace both structural materials and contents. A comprehensive inspection may include, but is not necessarily limited to, the following: • Identifying and evaluating health and safety hazards; • Determining the source of water; • Determining the need to protect floor covering materials and contents; • Determining the extent of moisture intrusion; • Determining the job scope; • Evaluating flooring materials; • Evaluating inventories and/or contents items; • Evaluating the HVAC system if affected; • Assess other structural materials (walls, ceilings, etc.); • Documenting preexisting conditions not related to the current loss (wear, urine contamination, delamination, etc.); and • Establishing drying goals. If the inspection conclusions require that any materials be removed, the project manager, building manager, or other responsible party is responsible to providing information regarding the presence of asbestos to the restoration contractor. This information is ONLY available through the Asbestos Program Office (3- 6435). In addition, the contractor must receive, sign, and return a job-specific FS-13 form prior to the start of work or any change in the scope of work. This document is an auditable document required by purchasing in order to process payment for any work performed by contractors on the NAU campus. Floor covering evaluation – It is recommended that a determination be made as to whether floor covering materials (e.g. carpet, cushion, vinyl, wood, laminates) are salvageable. Considerations may include, but are not necessarily limited to the following: • Construction integrity; and • Porosity and potential health effects from contaminants. Disposition of floor coverings and the ability to salvage them will be determined according to the appended Drying Standards. Structural Materials – Throughout the restoration process, it is highly recommended that effort is directed toward anticipating secondary damage and attending to other structural components that may require drying, or demolition and replacement. This is especially important if water remains in contact with building materials longer than 24 hours, such as water on flooring in contact with gypsum board. These components may include, but are not necessarily limited to the following: • Ceilings • Walls • Built-in furnishings and fixtures • Insulation • Structural wood Occupant Evacuation – For areas with extensive water damage, determine if occupants need to be evacuated from the damaged area, and, if so, estimate the duration of time. Factors used to make this determination may include, but are not necessarily limited to the following: • Type of contamination (e.g., Category 1,2, or 3 water); • Obvious indications of high levels of microbiological or chemical contamination; and, • Presence of occupants who are immunocompromised or have mold allergies, asthma or other applicable medical conditions. Technician Training – Technicians performing category 2 water (gray water) and category 3 water (black water) damage restoration must be trained in risks of exposure and procedures for safe cleanup of these materials. Personal Protection – Persons working in or around Category 3 water during the initial stage of decontamination, cleaning and biocide application must be equipped with personal protective equipment (PPE) including but not necessarily limited to the following: • Rubber gloves • Eye protection • Protective suit • Rubber boots An evaluation must be made to determine the necessity for respiratory protection. In the case of overhead hazards or contamination, hard hats must also be worn. APPENDIX A – DRYING AND REMEDIATION STANDARDS Criteria for determining when Building Materials are “Dry” The underlying principles that guided the development of these standards were: 1. The ambient conditions must be stabilized and be able to be held at normal room conditions; 2. The building materials must be returned to their equilibrium moisture content to prevent the active growth of fungal organisms; and 3. The building materials must be returned to their pre-loss moisture state. When these three criteria are met, a building can be considered dry. Drying services shall be considered sufficient when the following three conditions have been achieved. 1. The interior ambient conditions are at or better than normal room conditions (50%RH @ 70° F); 2. The moisture in the building materials themselves will not support the active growth of mold and mildew; and 3. The building materials and contents will finish returning to equilibrium with normal room conditions by themselves without further damage to them. Hardwood Floors – For the purposes of this Standard, drying services on a hardwood floor shall be considered sufficient when all four of the following conditions are met. 1. The moisture content (MC) of the wood is decreasing. 2. All affected wood is within 2.5% of its normal moisture content as determined by actual measurement in a control point elsewhere on the same floor. 3. The differential of MC in wood from the top ¼” to the bottom ¼” is no more than 1%. 4. The building environment is stabilized and the existing HVAC system is capable of maintaining normal room conditions. Drywall – Drying services for drywall will be provided by an outside contractor. If drying procedures are not initiated within 48 hours of the initial water loss or dried within 72 hours, all wet drywall should be replaced. For the purposes of this Standard, drying services on drywall shall be considered sufficient when all four of the following conditions are met: 1. The moisture content of the drywall is decreasing. 2. All affected drywall is within 10% of its normal moisture content as determined by actual measurement in a control point elsewhere in the same building. (Example: Taking several readings in unaffected areas of drywall showed that the MC that should be expected in the building is 14%. Therefore, the maximum reading at the end of the job should be no more than 24 %.) 3. The differential of MC in wood from the top ¼” to the bottom ¼” is no more than 1%. 4. The building environment is stabilized and the existing HVAC system is capable of maintaining normal room conditions. Concrete Block – For the purposes of this Standard, drying services on concrete block shall be considered sufficient when all four of the following conditions are met: 1. The moisture content of the concrete block is decreasing. 2. All affected concrete block is within 10% of its normal moisture content as determined by actual measurement in a control point elsewhere in the same building. (Example: Taking several readings in unaffected areas of concrete block showed that the MC that should be expected in the building is 10%. Therefore the maximum reading at the end of the job should be no more than 20%). 3. 95% of the affected concrete block area meets criteria 1 & 2. 4. The building environment is stabilized and the existing HVAC system is capable of maintaining normal room conditions. Plaster – For the purposes of this Standard, drying services on plaster shall be considered sufficient when all four of the following conditions are met: 1. The moisture content of the plaster is decreasing. 2. All affected plaster is within 10% of its normal moisture content as determined by actual measurement in a control point elsewhere in the same building. (Example: Taking several readings in unaffected areas of plaster showed that the MC that should be expected in the building is 10%. Therefore the maximum reading at the end of the job should be no more than 20%). 3. 95% of the affected plaster area meets criteria 1 & 2. 4. The building environment is stabilized and the existing HVAC system is capable of maintaining normal room conditions. Concrete – For the purposes of this Standard, drying services on concrete shall be considered sufficient when all four of the following conditions are met: 1. The moisture content of the concrete is decreasing. 2. All affected concrete is within 10% of its normal moisture content as determined by actual measurement in a control point elsewhere in the same building. (Example: Taking several readings in unaffected areas of concrete showed that the MC that should be expected in the building is 10%. Therefore the maximum reading at the end of the job should be no more than 20%). 3. 95% of the affected concrete area meets criteria 1 & 2. 4. The building environment is stabilized and the existing HVAC system is capable of maintaining normal room conditions. Carpeting – For the purposes of this Standard, drying services on carpeting may be effective if the following conditions are met: 1. The carpet is not wet with Category 1 or 2 water for more than 48 hours. 2. The carpet is not wet with Category 3 (black) water for any amount of time. 3. The building environment is stabilized and the existing HVAC system is capable of maintaining normal room conditions. 4. If 1 and 2 are not met, the carpet must be removed and replaced. Carpeting shall be steam-cleaned/sanitized and thoroughly dry prior to reoccupancy. Insulation: For the purposes of this Standard, thermal insulation materials used in walls or ceilings cannot be adequately dried and reused. If insulation material is determined to be wet, it must be removed from the building. The area where it was installed must be thoroughly cleaned, disinfected and dried. New insulation may then be installed. APPENDIX B – FLOOD RESPONSE PROCEDURE Purpose To identify the proper response procedure for University and other personnel when water/sewage flood damage is reported. Response Procedures A. Notifications 1. Upon discovery of a flood, call FAST 3-4227 during normal business hours. After business hours and on weekends notify the Central Plant Operator (3- 6412). Provide information to the Operator regarding the location, intensity and type of flood (i.e., sewage, stormwater, plumbing line, etc.). The Operator will notify the On-Call Supervisor. The Supervisor will then notify appropriate NAU staff. Outside vendors* may be necessary if the scope of damage exceeds the capability of NAU resources-especially if sewage is involved. Outside Vendor Assist (24/7)……………………….Qualified Vendor List* Operations & Maintenance………………………….3-1660 NAU Police ……..………………….…………………3-3611 Custodial Services (small Category 1 water)……..3-6565 NAU Industrial Hygienist………………………..…..3-6109 or 3-6435 * Qualified vendor is one that has met minimum State requirements concerning Insurance. An emergency purchase request should be sent to Purchasing within twenty-four (24) hours after calling the outside vendor to assist. * A Damage Report should be submitted as soon as possible (for non-criminal damage) to initiate the insurance claim process. The Damage Report is located on the NAU “Police/University” website (https://www4.nau.edu/police/). The Damage Report is not a police report and will be issued a claim number by the Insurance Officer at Property and Liability Insurance Services. However, if the damage is due to vandalism/criminal damage, immediately contact NAU Police Dispatch, 523-3611, to file a police report. For additional information about filing a claim for damages, contact NAU’s Insurance Officer with Property and Liability Insurance Services (523-2009). B. Evacuation/Perimeter Control 1. In a situation where floods are uncontrolled or involve infectious waste or other hazards (electrical), staff may be instructed to evacuate the area by NAU Regulatory Compliance, appropriate Capital Assets and Services Staff, or other responders (NAU PD or outside contractor). 2. Perimeter control must be established by staff in the area with assistance from NAU Regulatory Compliance, Custodial Services, or other responders. 3. The remediation contractor will tape off affected areas and divert traffic in such a fashion to minimize public exposure to the affected areas. C. Pre-Restoration Action 1. Responders entering the affected areas will wear the appropriate personal protective equipment (i.e., impervious boots, impervious gloves, goggles, and face shield and protective clothing if splashing is likely). 2. Photographs should be retained for insurance documentation and submitted to the Insurance Officer, Property and Liability Insurance Services, as supporting documentation for the property damage claim. Please write the claim number on all supporting documentation sent. 3. Responders will establish a Decontamination Zone as follows: a. An approved disinfectant (see Definitions) shall be used to decontaminate equipment that is removed from the contaminated area. b. To control the spread of potentially infectious material to clean areas, all persons leaving the affected area shall walk across the Decontamination Zone barrier, which consists of: i. Disinfectant soaked disposable absorbent pads placed on a clean area of the floor, ii. Clean disposable absorbent pads damped with water placed on the clean side of the floor, iii. Clean, dry disposable absorbent pad placed at the end of the Decontamination Zone to dry material passing through. c. All materials used for remediation of the flood must either be decontaminated with an approved disinfectant prior to leaving the flood area or discarded. This includes all plumbing tools and reusable flood response equipment. D. Containment Materials 1. Responders shall maintain spill containment materials. 2. Responders shall place spill barriers around the affected areas in order to contain the flood from potential migration to unaffected areas. 3. Reusable spill barriers shall be decontaminated by responders with a disinfectant and returned to storage. E. Exposure Procedures 1. If university personnel or students have come in contact with sewage flood water, the following should occur: a. Remove contaminated clothing. b. Wash affected area with soap and water. c. Go to the Fronske Health Center for follow-up treatment. F. Asbestos Precautions 1. Because asbestos is present in various building materials of many buildings on campus, no disturbance including removal of flooring or wall materials may be conducted without prior authorization by the Asbestos Program Office. a. Contractors, building managers, project managers, or other responsible parties may contact the asbestos program office directly at 3-6435. b. Restoration Contractors must sign and return a copy of the NAU FS-13 form prior to the commencement of work. This is an auditable document which confirms that the contractor has received asbestos information pertinent to the project at hand. Purchasing requires this document to complete processing of payment for any work performed.

Mold (American English) or mould (British English), also sometimes referred to as mildew, is a fungal growth that develops on wet materials. Mold is a natural part of the environment and plays an important part in nature by breaking down dead organic matter such as fallen leaves and dead trees; indoors, mold growth should be avoided. Mold reproduce by means of tiny spores. The spores are like seeds, but invisible to the naked eye, that float through the air and deposit on surfaces. When the temperature, moisture, and available nutrient conditions are correct, the spores can form into new mold colonies where they are deposited.^[1] There are many types of mold, but all require moisture and a food source for growth.

Health effects[edit]

Mold is ubiquitous, and mold spores are a common component of household and workplace dust. In large amounts they can be a health hazard to humans, potentially causing allergic reactions and respiratory problems.

Mycotoxins[edit]

Some mold produce mycotoxins, chemical components of their cells walls, that can pose serious health risks to humans and animals. “Toxic mold” refers to mold which produce mycotoxins, such as Stachybotrys chartarum.^[2] Exposure to high levels of mycotoxins can lead to neurological problems and death. Prolonged exposure (for example, daily exposure) can be particularly harmful. Mycotoxins can persist in the indoor environment even after death of the fungi. They can adhere to dust particles and can spread through the air attached to these dust particles or spores.^[3] There must be very specific temperature and humidity conditions in order for fungi to produce mycotoxins.^[3]

Symptoms[edit]

Symptoms of mold exposure may include nasal and sinus congestion; runny nose, eye irritation; itchy, red, watery eyes, respiratory problems, such as wheezing and difficulty breathing, chest tightness, cough, throat irritation, skin irritation (such as a rash), headache, and persistent sneezing.^[4] Immune-compromised people and people with chronic lung illnesses, such as obstructive lung disease, may get serious infections in their lungs when they are exposed to mold. These people should stay away from areas that are likely to have mold, such as compost piles, cut grass, and wooded areas.^[5]

Asthma[edit]

Infants may develop respiratory symptoms as a result of exposure to Penicillium, a fungal genus. Signs of mold-related respiratory problems in an infant include a persistent cough or wheeze. Increased exposure increases the probability of developing respiratory symptoms during the first year of life. Studies have indicated a correlation between the probability of developing asthma and exposure to Penicillium.^[6]

Mold exposure has a variety of health effects, and sensitivity to mold varies. Exposure to mold may cause throat irritation, nasal stuffiness, eye irritation, cough and wheezing and skin irritation in some cases. Exposure to mold may heighten sensitivity, depending on the time and nature of exposure. People with chronic lung diseases are at higher risk for mold allergies, and will experience more severe reactions when exposed to mold. Damp indoor environments correlate with upper-respiratory-tract symptoms, such as coughing and wheezing in people with asthma.^[7]

Causes and growing conditions[edit]

Mold is found everywhere and can grow on almost any substance when moisture is present. They reproduce by spores, which are carried by air currents. When spores land on a moist surface suitable for life, they begin to grow. Mold is normally found indoors at levels which do not affect most healthy individuals.

Because common building materials are capable of sustaining mold growth and mold spores are ubiquitous, mold growth in an indoor environment is typically related to water or moisture exposure and may be caused by incomplete drying of flooring materials (such as concrete). Flooding, leaky roofs, building-maintenance or indoor-plumbing problems can lead to interior mold growth. Water vapor commonly condenses on surfaces cooler than the moisture-laden air, enabling mold to flourish.^{[citation needed]} This moisture vapor passes through walls and ceilings, typically condensing during the winter in climates with a long heating season. Floors over crawl spaces and basements, without vapor barriers or with dirt floors, are mold-prone. The “doormat test” detects moisture from concrete slabs without a sub-slab vapor barrier.^{[citation needed]} Some materials, such as polished concrete, do not support mold growth.

Significant mold growth requires moisture and food sources and a substrate capable of sustaining growth. Common cellulose-based building materials, such as plywood, drywall, furring strips, finish carpentry, cabinetry, wood framing, composite wood flooring, carpets, and carpet padding provide food for mold. In carpet, organic load such as invisible dust and cellulose are food sources. After water damage to a building, mold grows in walls and then becomes dormant until subsequent high humidity; suitable conditions reactivate mold. Mycotoxin levels are higher in buildings which have had a water incident.

Hidden mold[edit]

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; and 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.^{[citation needed]}

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. Mold grows 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).^{[citation needed]}

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); and warmth since 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.

Assessment[edit]

An observation of the indoor environment should be conducted before any sampling is performed. The area should be surveyed for odors indicating mold or bacterial growth, moisture sources, such as stagnant water or leaking pipes, and water-damaged building materials.^[9] This can include moving furniture, lifting (or removing) carpets, checking behind wallpaper or paneling, checking ventilation ductwork and exposing wall cavities. Efforts typically focus on areas where there are signs of liquid moisture or water vapor (humidity), or where moisture problems are suspected. Often, quick decisions about the immediate safety and health of the environment can be made by these observations before sampling is even needed.^[9] The United States Environmental Protection Agency (EPA) does not generally recommend sampling unless an occupant of the space has symptoms. In most cases, if visible mold growth is present, sampling is unnecessary.^[10] Sampling should be performed by a trained professional with specific experience in mold-sampling protocols, sampling methods and the interpretation of findings. It should be done only to make a particular determination, such as airborne spore concentration or identifying a particular species.

Sampling[edit]

Before sampling, a subsequent course of action should be determined.

In the U.S., sampling and analysis should follow the recommendations of the Occupational Safety and Health Administration (OSHA), National Institute for Occupational Safety and Health (NIOSH), the EPA and the American Industrial Hygiene Association (AIHA). Types of samples include air, surface, bulk, dust, and swab.^[3] Multiple types of sampling are recommended by the AIHA, since each has limitations.^[11]

Air sampling[edit]

Air is the most common form of sampling to assess mold levels. Although, the Environmental Protection Agency (EPA) does not have any current testing protocols. Air sampling is considered to be the most representative method for assessing respiratory exposure to mold.^[12] Indoor and outdoor air are sampled, and their mold spore concentrations are compared. Indoor mold concentrations should be less than or equal to outdoor concentrations with similar distributions of species.^[3] A predominant difference in species or higher indoor concentrations can indicate poor indoor air quality and a possible health hazard.^[3] Air sampling can be used to identify hidden mold and is often used to assess the effectiveness of control measures after remediation.^[12] An indoor mold air sampling campaign should be performed over the course of at least several days as the environmental conditions can lead to variations in the day-to-day mold concentration.^[12] Stationary samplers assess a specific environment, such as a room or building, whereas personal samplers assess the mold exposure one person receives in all of the environments they enter over the course of sampling.^[12] Personal samplers can be attached to workers to assess their respiratory exposures to molds on the job.^[12] Personal samplers usually show higher levels of exposure than stationary samples due to the “personal cloud” effect, where the activities of the person re-suspend settled particles.^[12] There are several methods that can be used for indoor mold air sampling.

Swab and surface sampling[edit]

Surface sampling measures the number of mold spores deposited on indoor surfaces. With swab, a cotton swab is rubbed across the area being sampled, often a measured area, and subsequently sent to the mold testing laboratory. The swab can rubbed on an agar plate to grow the mold on a culture medium. Final results indicate mold levels and species located in the suspect area. Surface sampling can by used to identify the source of mold exposure. Molecular analyses, such as qPCR, may also be used for species identification and quantification. Swab and surface sampling can give detailed information about the mold, but cannot measure the actual mold exposure because it is not aerosolized.^[12]

Bulk and dust sampling[edit]

Bulk removal of material from the contaminated area is used to identify and quantify the mold in the sample. This method is often used to verify contamination and identify the source of contamination.^[12] Dust samples can be collected using a vacuum with a collection filter attached. Dust from surfaces such as floors, beds, or furniture is often collected to assess health effects from exposure in epidemiology studies.^[12] Researchers of indoor mold also use a long-term settled dust collection method where a dust cloth or petri dish is left out in the environment for a set period of time, sometimes weeks.^[12] Dust samples can be analyzed using culture-based or culture-independent methods. Quantitative PCR is a DNA-based molecular method that can identify and quantify fungal species. The Environmental Relative Moldiness Index (ERMI) is a numerical that can be used in epidemiological studies to assess mold burdens of houses in the United States. The ERMI consists of a list of 36 fungal species commonly associated with damp houses that can be measured using qPCR.^[13][12] Like swab and surface sampling, bulk and dust sampling can give detailed information about the mold source, but cannot accurately determine the level of exposure to the source.^[12]

Remediation[edit]

The first step in solving an indoor mold problem is to remove the moisture source;^[14] new mold will begin to grow on moist, porous surfaces within 24 to 48 hours. There are a number of ways to prevent mold growth. Some cleaning companies specialize in fabric restoration, removing mold (and mold spores) from clothing to eliminate odor and prevent further damage to garments.

The effective way to clean mold is to use detergent solutions which physically remove mold. Many commercially available detergents marketed for mold cleanup include an EPA-approved antifungal agent.^[15][16]

Mould will start to grow once moisture and organic material come together. This can happen anywhere in a property including bathrooms, walls, garages, bedrooms kitchen, etc. A smell is a good indicator that there is mold growth that needs immediate attention. If not attended to, the growth can spread through the property contributing to adverse health problems and causing secondary damage to the structure and its contents.^[17] Significant mold growth may require professional mold remediation to remove the affected building materials and eradicate the source of excess moisture. In extreme cases of mold growth in buildings, it may be more cost-effective to condemn the building than to reduce mold to safe levels.^{[citation needed]}

The goals of remediation are to remove (or clean) contaminated materials, preventing fungi (and fungi-contaminated dust) from entering an occupied (or non-contaminated) area while protecting workers performing the abatement.^[18]

Cleanup and removal methods[edit]

The purpose of cleanup is to eliminate mold and remove contaminated materials. Killing mold with a biocide is insufficient, since chemicals and proteins causing reactions in humans remain in dead mold. The following methods are used.

• Evaluation: Before remediation, the area is assessed to ensure safety, clean up the entire moldy area, and properly approach the mold. The EPA provides the following instructions:^[8]
• HVAC cleaning: Should be done by a trained professional.^[19]
• Protective clothing: Includes a half- or full-face respirator mask. Goggles with a half-face respirator mask prevent mold spores from reaching the mucous membranes of the eyes. Disposable hazmat coveralls are available to keep out particles down to one micrometer, and protective suits keep mold spores from entering skin cuts. Gloves are made of rubber, nitrile, polyurethane, or neoprene.^[8][18]
• Dry brushing or agitation device: Wire brushing or sanding is used when microbial growth can be seen on solid wood surfaces such as framing or underlayment (the subfloor).
• Dry-ice blasting: Removes mold from wood and cement; however, this process may spray mold and its byproducts into surrounding air.
• Wet vacuum: Wet vacuuming is used on wet materials, and this method is one of those approved by the EPA.^{[citation needed]}
• Damp wipe: Removal of mold from non-porous surfaces by wiping or scrubbing with water and a detergent and drying quickly.
• HEPA (high-efficiency particulate air) vacuum: Used in remediation areas after materials have been dried and contaminated materials removed; collected debris and dust is stored to prevent debris release.
• Debris disposal: Sealed in the remediation area, debris is usually discarded with ordinary construction waste.

Equipment[edit]

Equipment used in mold remediation includes: moisture meter: measures drying of damaged materials; Humidity gauge: often paired with a thermometer; borescope: Camera at the end of a flexible snake, illuminating potential mold problems inside walls, ceilings and crawl spaces; digital camera: Documents findings during assessment; personal protective equipment (PPE): Respirators, gloves, impervious suit, and eye protection; thermographic camera: Infrared thermal-imaging cameras identify secondary moisture sources.

Protection levels[edit]

During mold remediation in the U.S., the level of contamination dictates the protection level for remediation workers.^[20] Contamination levels have been enumerated as I, II, III, and IV:^{[citation needed]}

• Level I: Small, isolated areas (10 square feet (0.93 m²) or less); remediation may be conducted by trained building staff;
• Level II: Mid-sized, isolated areas (10–30 square feet (0.93–2.79 m²)); may also be remediated by trained, protected building staff;
• Level III: Large, isolated areas (30–100 square feet (2.8–9.3 m²)): Professionals experienced in microbial investigations or mold remediation should be consulted, and personnel should be trained in the handling of hazardous materials and equipped with respiratory protection, gloves and eye protection;
• Level IV: Extensive contamination (more than 100 square feet (9.3 m²)); requires trained, equipped professionals

After remediation, the premises should be reevaluated to ensure success.

Residential mold prevention and control[edit]

According to the EPA, residential mold may be prevented and controlled by cleaning and repairing roof gutters, to prevent moisture seepage into the home; keeping air-conditioning drip pans clean and drainage lines clear; monitoring indoor humidity; drying areas of moisture or condensation and removing their sources; ensuring that there is adequate ventilation by installing an exhaust fan in your bathroom; treating exposed structural wood or wood framing with an EPA-approved fungicidal encapsulation coating after pre-cleaning (particularly homes with a crawl space, unfinished basement, or a poorly-ventilated attic).^[8]

See also