What is mold and how does it grow?
There are more than 100,000 identified species of fungi existing naturally in our environment today. Species have existed for millions of years, are generally present throughout the world at ambient airborne levels, and have limited negative impact on mankind. Upon germination, fungi become mold. Germination or reproduction of fungi occurs when fungi, which are naturally present in building materials (such as ceiling tiles, drywall, insulation, etc.), are exposed to moisture. As long as the moisture is present the fungi will reproduce (grow) until a potentially serious human health issue is created.
Can mold impact our health?
Inhalation of elevated levels of airborne fungi may result in an allergic or even toxic response. Individuals who are already immune compromised and small children are particularly vulnerable.
How long does moisture need to be present for a mold problem to develop?
Generally, building materials must remain wet for more than 24-48 hours for molds to develop. If mold is visible prior to that time it is likely from a preexisting water problem and not from the immediate occurrence. It is therefore extremely important to respond quickly to issues of water incursion by repairing the source of the leak, thoroughly drying all wet materials, and removing moisture from the air, as soon as a leak is discovered.
Are molds always visible?
Once molds become visible they must be removed. A visual inspection is an important first step in any microbial investigation. Unfortunately, molds thrive in environments where there is a lack of ventilation such as in wall cavities, subfloors, beneath wall/floor coverings, behind vapor barriers, and behind ceiling tiles. Therefore, when microbial growth is suspected it is critical to investigate all areas thoroughly for potential water impact.
When will molds become airborne?
Until the source of water intrusion is eliminated and all impacted materials dried, molds will continue to grow. Eventually molds will become aerosolized (airborne). This occurs when fungus germinates and distributes millions of spores in hopes of reproduction. Generally the longer the molds have been germinating the higher the spore counts and the more likely the molds have become aerosolized. Drying out building materials and molds may stop the mold growth but it may also make the dead mold spores more likely to aerosolize. Therefore, if the drying process is performed in an area with existing mold it should be performed only under carefully controlled conditions.
When is mold exposure harmful?
We are constantly exposed to thousands of different types of fungi in our everyday lives. Certain types of fungi tend to exist naturally in soils, plants, fruits, and textiles in our environment. Exposure to these fungi in naturally occurring doses is generally not harmful to our health. Exposure to these fungi at levels which exceed those naturally existing in the environment may be harmful. Therefore, when a microbial investigation is performed, the levels and types of fungi present in the internal environment should be compared with those existing naturally in the outside environment. Should the indoor composition significantly vary quantitatively or qualitatively (genus or species) from the out- side composition, microbial magnification should be suspected.
What are some commonly found fungi which exist naturally in the environment?
While the types and concentrations of fungi existing in the environment vary from one geographic region to another, the more common types are as follows: Aspergillus (most common), Alternaria, Bipolaris, Chaetomium, Cladosporium, Fusarium, Penicillium, and Paecilomyes.
What levels of exposure are harmful?
There are no established safe exposure limits for any fungi and all may be potentially harmful. Individual health and sensitivities will dictate on a unique basis both the impact (i.e. particular health effect) and duration of illness as a result of exposure. Individuals who are immune compromised, infants, and small children whose immune systems are less developed, may be more severely impacted by exposure and may experience long term health effects.
What is Stachybotrys?
Stachybotrys is a fungi which has received tremendous media attention recently. It is a black, slimy mold which requires an ongoing water source and/or extremely high humidity to grow. Once the drying process begins, the Stachybotrys mold, which is a very fragile mold, is generally replaced by Aspergillus or Penicillium. The mold’s “slimy” characteristic is an important factor in why it is not often found in an aerosolized form. If this mold is found and has become aerosolized, it generally indicates that water intrusion has been ongoing for some time. Stachybotrys is a mold which se- lectively chooses a host of cellulose building materials as well as products containing wood, paper, or cotton. This is not the black mold in your shower or the green mold on your cheddar cheese.
If the presence of mold is suspected, what are the important risk factors to look for?
- A. Is visible mold present or is there a strong musty odor?
- Risk: May indicate a long-term problem and consequently higher levels of potentially toxic mycotoxins.
- B. Are there immune compromised individuals or small children living or working in close proximity to the suspected areas of impact?
- Risk: May indicate the need to exercise greater diligence investigation as well as remediation. Even relatively low levels of fungi may cause these individuals to suffer adverse health effects.
- C. Are occupants complaining of health related illnesses which can be linked to microbial exposures?
- Risk: If occupants are complaining of symptoms which may be linked to mold exposure, it may signify either the presence of relatively high levels of bioaerosols or the possibility that immune compromised or hypersensitive individuals are present.
- D. Are other environmental issues potentially involved?
- Risk: If there is the possibility that other environmental hazards such as asbestos, lead based paint, non-microbial industrial hygiene issues, etc. may be impacted either in the investigation or the remediation, certain proper precautions need to be taken so as not to aggravate the existing situation.
- E. Does the suspected area of impact involve a high risk environment such as a hospital, food preparation area, infant day care, etc.?
- Risk: Due to the obvious higher exposure risk in these environments, the highest levels of diligence should be used in evaluating and defining areas of impact.
What are some of the potential health consequences of mold exposure?
Some of the most common health effects that may result from exposure to high levels of mold include: allergic responses, headaches, dermatitis, asthma, eye problems, diarrhea, vomiting, nausea, fever, respiratory illnesses, and ear infections. It is thought that exposure to specific fungi will develop certain types of illness; therefore, it is important to document specific complaints of ill health which may then be traced back to exposure to a specific mold.
When is there a need to conduct a microbial investigation?
A microbial investigation should be performed based on the evaluation of the following factors:
- Is there current or past water damage particularly to building materials (cellulose, drywall, wood) that have been wet more than 24-48 hours?
- Is visible mold present?
- Are occupants complaining of health issues which coincide with the presence of water damage?
- Are immune compromised individuals or infants located in close proximity to areas of impact?
- Is there evidence of hidden microbial growth (i.e. odors) and/or is there evidence of past moisture problems?
- Are ambient moisture levels high?
- Is there visible microbial evidence in the HVAC system and/or wet filters, standing water, dirty surfaces?
What should the microbial investigation accomplish?
Once it is determined that a microbial investigation should be performed, a broad spectrum of sampling techniques should be performed so that the full extent of contamination can be delineated, the fungal reservoir identified, and an appropriate remediation/restoration plan developed, if needed.
Who should perform the microbial investigation?
The investigation should be performed by an individual with microbial investigation experience, preferably an industrial hygienist with microbiology or toxicology ex- perience. A Certified Industrial Hygienist (CIH) may possess a good background for this type of work.
What type of laboratory should analyze the samples?
The samples taken should be analyzed by an independent microbial laboratory which regularly performs this rype of analysis. The laboratory should participate in the American Industrial Hygiene Association Microbiology Pat Program.[/learn_more
What type of sampling and activities should be included in a microbial investigation?
The first step in a microbial investigation should be to examine the building layout and HVAC system. Next, a thorough visual observation of the building should be performed after discussion with knowledgeable personnel concerning the location and cause of water intrusion. The duration of water intrusion as well as the date of the event may also be important. Sampling should always include a variety of the following samples because sampling is a snapshot of conditions existing at me time of the investigation. Varying the types of samples as well as varying the sample location and time will ensure a more representative picture of the actual conditions.
Types of Microbial Sampling
- Surface – Bulk, Swab, or Tape Samples
- Air Samples – Viables/Nonviables – taken inside as well as outside
A variety of surface sampling should be performed because areas of impact may be missed or may not be conducive to certain types of surface sampling. Air sampling should always be performed outside as well as inside so that a comparison of quantity and type of mold/bacteria present inside the building can be made to that which naturally exist in the environment. Sampling for bacteria should also be included as part of a fungal (mold) investigation because the presence of certain types of bacteria may indicate a water impact and thereby validate fungal results. In addition, if the water impact was the result of a sewer or other “dirty water” problem, the presence of bacteria may exist along with fungi to produce additional health Issues.
What steps should you take once mold is identified?
- Fix or stop the cause of moisture
- React promptly – dry and clean impacted areas
- Hire appropriate professionals
- Develop and follow a plan of action for water problems (i.e. Industrial Hygiene 0 & M Plan)
- Document all actions
If it is determined that remediation of the impacted area is necessary, what procedures should be followed?
- Develop a remediation plan detailing the method, scope, time, and controls to be used.
- Inform all parties impacted and determine if they need to be relocated.
- Impacted items need to be removed under negative pressure containment and in such a manner that does J not contaminate clean areas.
- All items/materials that can be cleaned should be itemized along with the cleaning method.
- HVAC system needs to be evaluated for impact and should be decontaminated if necessary.
- Visual examination should be made to ensure all visible contamination has been removed.
- Upon project completion, clearance sampling should be performed to ensure areas are safe for reoccupancy.