Providing Sound Environmental Solutions for Business and Industry

Mold Investigation & Remediation Services

TTI Environmental, Inc. (TTI) offers professional mold investigation and remediation services.  TTI's services includes: 

Mold – General Overview

Microorganisms are a normal and essential component of all environments.  There are three (3) general requirements for microbial growth: a favorable physical environment (light & temperature), a source of food, and moisture.  Microbes, as a group, have adapted well through evolution and are able to colonize most environments.  Depending on the source of carbon used as a food, ambient conditions, and the amount of moisture available, some species are likely to colonize almost any available area.

Since favorable environments and sources of food are available in most areas of any home, the availability of moisture generally becomes the controlling factor for microbial growth.  The presence of excessive moisture and/or evidence of water damage are used as surrogates for identifying potential growth areas.  The presence of free water is generally associated with bacterial growth, while moist air without free water lends to potential fungal growth.

Microorganisms and/or their reproductive structures are almost always found in outdoor air, although their type and population will vary depending on environmental and climatic conditions.  Doors and windows provide easy access to the interior of buildings.  It is normal to find some quantity of microorganisms in indoor air, although their numbers should be significantly less than outdoor levels.

Excessive moisture from leaks, floods or other sources inside a building can create an environment, which will tend to amplify their population.  Depending on the amount of water, temperature, lighting and food source available, different species may become dominant.  The presence of some microorganisms in significantly large quantities may lead to adverse health effects in building occupants.  Both the presence and concentration of microorganisms as well as the susceptibility of the exposed individuals may drive the incidence and severity of these effects.

In cases of major water incursion into a structure, it is critical to dry the interior as quickly as possible.  Many factors will affect the rate of growth, but minimal impact is generally only encountered if dehumidification can be initiated within 48 hours.  The longer the home remains wet or damp, the more moisture will be absorbed by vulnerable materials and the more extensive the colonization is likely to be.

Clothes, paper, cardboard, upholstered furniture, and pressed wood products are typically the most vulnerable.  Hardwoods, synthetics, metallic components, coated materials, and those protected by vapor barriers tend to resist absorption and are generally slower to be colonized.  Moisture is absorbed fastest through direct contact with free water and more slowly through exposure to moist air.

Colonization is generally most extensive in areas with direct contact with free water, those that are enclosed, and on materials that have been previously colonized.  As the water evaporates, airflow patterns within the home will move moisture throughout, including the interior of walls.  Cold spots become condensing surfaces that act as secondary sources of free water at locations often far removed from the original leak or point of entry.

In cases where the mitigation is not initiated for two weeks or more, colonization may become so extensive as to begin to threaten the health of occupants and remediation workers.

Controls must be put in place to minimize growth, limit dispersion of microbes and their reproductive structures, and to minimize exposure to workers and residents.

When a residence has suffered a water casualty of significant magnitude, it is important to develop an effective and comprehensive strategy for restoring it to its preexisting condition.  It is imperative that the root causes of the water incursion be corrected or the condition is likely to recur.

Contractors should be screened to assure that they are properly trained, experienced, and well equipped.  Work objectives must be clearly stated and their achievement validated through thorough inspection and sampling.  Each step of their work should be properly documented and records maintained for future considerations.

In cases of extensive colonization, colonized absorptive materials are generally discarded because they are either structurally damaged or not cost effective to sanitize.  Less absorptive materials must be cleaned, sanitized and dried.  Materials prone to future wetting are most vulnerable and should be treated to give them residual microbial resistance.

Once damaged materials and active growth have been removed, all surfaces should be HEPA vacuumed, sanitized, treated as appropriate and thoroughly dried.

A thorough visual inspection and representative sampling should then be conducted to check for structural damage and determine the need for any further mitigation action.

Once mitigation is completed, representative sampling should be conducted to validate the effectiveness of the clean up.

Currently, there are no regulatory standards for acceptable levels of microorganisms in bio-aerosols, wipes or bulk samples derived from residential indoor environments.  Interpretation of the significance of qualitative and quantitative results varies from site to site and from practitioner to practitioner.  As a result, site specific clearance criteria are often based on generally defined guidelines offered by recognized organizations such as the American Industrial Hygiene Association (AIHA) in Field Guide for the Determination of Biological Contaminant in Environmental Samples, 1996 and the American Conference of Governmental Industrial Hygienists (ACGIH) in Bio-aerosols 1999.  These organizations generally agree that properly mitigated areas should be visually observed to be free of any microbial colonization and particulate debris.  Bio-aerosols results should not exceed outdoor or control levels and display similar species distribution as the outdoors or controls.

Surface wipe samples exhibiting microbial populations from 0 to 1500 CFUs/inch² are often encountered on un-impacted wood components of structures.  For the purpose of microbial mitigations, vertical surface populations greater than 1500 CFUs/inch² are often considered in need of mitigation.

TTI’s Role

Initial Mold Investigation

An initial mold investigation and evaluation involves a visual inspection of the interior and exterior of a building or home for evidence of mold, water and moisture.  Occupant interviews are used to ascertain any symptoms or concerns the occupants or property owners may have.  A general inspection protocol includes, but is not limited to, locating the mold and moisture, assessing the mold and moisture to determine the source, performing measurements (temperature, humidity, etc.), and conducting mold sampling, if appropriate.  After the inspection is completed, a comprehensive report is prepared.  The report includes an explanation of the extent and location of any mold or moisture, location of any active leaks, interpretation of the sampling data and recommendations for the remediation of the mold problem. 

Mold Sampling Methods

The microbial sampling consists of collecting fungal spore trap air samples, fungal bulk samples and/or fungal tape lift samples. 

Fungal spore trap air samples are collected by using an Air-O-Cell cassette attached to a high volume vacuum pump.  A volume of air is drawn through the cassette and the contents of the air are deposited upon a specially treated glass slide, which is then analyzed by a mycologist who identifies fungal types and quantity.  Fungal spore trap air samples measure both viable and non-viable fungal spores.

Fungal spore trap air samples are collected from the outdoors to be used as a comparison to the inside samples.  There are currently no guidelines for interpreting fungal air sample results.  It is generally accepted that indoor airborne fungal concentrations should be approximately the same or below those found outdoors, and display similar species distribution.  Elevated indoor airborne fungal concentrations as compared to outdoor concentrations are often an indicator of a fungal amplification source due to a moisture condition.

A bulk sample is a small piece of building material (i.e. a piece of carpet, cardboard, wood, etc.) that can act as substrate for microbial growth.  The purpose of collecting the bulk sample is to determine the type of suspected fungi within that substrate. 

Tape lift samples are collected by applying a three (3) inch strip of clear tape on a smooth surface that has suspected visible fungal growth on it.  By gently rubbing the tape, a portion of the mold growth is stuck to the tape.  The tape is then placed on a glass microscope slide.  The slide is then sent to an accredited microbiology lab and analyzed by an experienced mycologist.  

Remediation Work Plan Design

The mold remediation work plan is designed for a mold remediation contractor to follow, so that all remediation activities are performed properly and all areas of mold contamination are addressed.  Specific work area recommendations are listed for solving the problems that were found.  A typical work plan will include a removal and cleaning schedule, specific work area and cleaning requirements and the terms for a final inspection and clearance sampling.  Also, in the work plan is a description of appropriate personal protection, proper work are containment, clean up and disposal procedures. 

Final Inspection and Clearance Sampling

After a mold remediation project is complete, a final inspection and clearance sampling will be performed.  The final inspection will include confirmation that:

Air and/or wipe samples will be collected upon final inspections of remedial areas.  The analytical results will determine if the remedial areas are cleared for re-occupation or if additional remediation will be required.  If post remediation samples do not meet the clearance standards, then the remediation contractor is responsible for the additional costs of the samples, including labor costs.

It should be noted that mold remediation projects do not result in a sterile environment and it is impossible to remove all mold spores in the work area.

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