Frequently Asked Questions - Remediation and Testing Questions

The term “toxic” can be very misleading. Anything, including water, can be toxic at the right dose. A better term might be “toxigenic” which would indicate that the mold has the POTENTIAL to produce mycotoxins, and those molds that are toxigenic do not always produce toxins. The production of mycotoxins is determined by the environmental conditions and is not well researched.When people talk about “toxic black mold”, most often they are referring to Stachybotrys.  The reality is that many species of mold are toxigenic and color is not a reliable way to identify mold. Stachybotrys is what we call a “tertiary colonizer” which means it’s not the first type of mold to show up after water intrusion. Stachybotrys has a relatively high moisture requirement, so it is usually found in areas where cellulose materials have been saturated for a long time. From a remediation perspective, Stachybotrys is a relatively large spore, and therefore more likely to settle out… which makes it an easier mold to clean.

Mold needs only two things for growth; a food source, and moisture.  We have no control over the food sources within our home, as any organic material is potential mold food, but we can control the moisture.Repairs to leaking windows, pipes, appliances, etc., should be made immediately. Water damage that results from a sudden discharge of water, within the last 48 hours, can usually be dried by a professional water damage restoration company.  Water damage that is older than 48 hours can usually be assumed to have some degree of mold growth, whether visible or not, and should be properly documented and remediated.Condensation on exterior walls is common in older, uninsulated homes.  This can be prevented by ventilating the home, insulating the walls and ceiling, and replacing old aluminum framed windows with new vinyl framed windows.

The first step is to identify and repair the source of moisture.  Mold will not grow without moisture. The second step is to assess the situation.  How much mold is present?  Do you have any liability… can you get sued?  Are there any health concerns?  How you answer these questions will determine the next steps.The decision to do-it-yourself or hire it out is always a tough one, and there is no wrong answer. Should you choose to hire it out, and we highly recommend this option, you should choose a contractor that has the proper training and equipment. Should you choose to do-it-yourself, you should purchase the proper equipment and get some guidance proper personal protection and remediation techniques. In either case, post-remediation testing is always recommended to ensure the project was completed correctly.

There is always air movement through walls and floors.  Contaminants that exist in crawlspaces, attics, and wall cavities have the potential to enter your home and degrade the indoor air quality.

Dirty air duct systems are a common contributor to poor indoor air quality. Even clean duct systems can be a transport mechanism for airborne spores to move through a structure and spread the contamination. Pacific IAQ recommends that the HVAC system be turned off immediately when a mold problem is discovered.

Physical removal is always the best way to get rid of mold. This means removal of affected drywall, carpet, padding and other porous materials, and detailed cleaning of semi-porous and non-porous materials.  HEPA filtered air scrubbers are used to physically remove airborne spores.

Bleach can be effective at killing mold and removing the stains caused by mold, but bleach is not recommended because it does not actually remove the mold.  Pacific IAQ recommends a mild surfactant solution (dish soap and water) as a cleaning solution on semi-porous and non-porous materials (porous materials with mold growth are generally not cleanable). We recognize that bleach is a cost effective antimicrobial, and that many homeowners will use bleach regardless of what we recommend, so if you do use bleach remember that a 10:1 solution of water and bleach is more effective than straight bleach.  Also, if you use bleach, reapply as often as necessary to keep the area wet for at least 30 minutes, and always use it in a well ventilated area, as the byproducts of bleach may be more harmful than the mold you are cleaning.

Mold growth on drywall is an indication of a moisture problem. Painting over the mold will not fix the problem. Once mold growth has been established, it takes very little moisture (as low as 70% relative humidity in the air) to continue to support the growth. Mold that is trapped under a layer of paint will continue to grow and will, eventually, return.

The law is not clear on this issue, and laws differ from state to state.  A landlord must provide you with a safe living space. That means that any environmental conditions that could adversely affect your health must be fixed.  The problem with mold is that it is a natural organism that exists in every home to some extent.  Pacific IAQ has been on both sides of this legal issue and more often than not, the law favors the tenants when a landlord fails to address mold and water damage issues.

You need to sample for mold when you suspect that you have a problem and you need to know the extent of the problem.  If you have a dark mold-like growth on your wet drywall, you don’t need a laboratory to tell you its mold. What you may need to know is how that mold has affected your living space… is it confined to that one area or has it become airborne and spread throughout the home? The best way of detecting mold is through your olfactory senses (smell). That musty, moldy smell is usually the microbial volatile organic compounds (MVOC’s) produced by mold, and is a good indicator that you have a mold problem.

On an initial mold investigation, Pacific IAQ does not always recommend mold sampling.  As degreed scientists, we believe that any test should be conducted with the specific purpose of answering a question. If you have visible mold growth on your wall then we don’t need a surface sample to answer the answer the question “is that mold?”.  If you have a reaction to a specific mold and the question is “is that Aspergillus niger” then a surface sample is a very good option.  In general, mold samples fall into two categories; viable and nonviable, and within each of those categories we can collect air samples, surface samples, or bulk samples. The samples are sent to an accredited laboratory where they are examined under direct microscopy. The type of sample taken depends on the specific question we are trying to answer.Another method that we can use is qPCR analysis. This is a quick sample, with results in about two days, but considerably more expensive. The advantage of qPCR analysis is that we get the most accurate speciation, and the most accurate quantification of the molds present.  This method is typically used in legal cases.

First we have to look at the differences between viable and nonviable sampling:Viable Sampling – Viable sampling only documents mold that is alive and able to grow and produce spores. Nonviable sampling documents all spores, alive and dead. The advantage of viable sampling is that the mold is actually grown out on a Petri dish and mycologists are able to identify the mold down to the species level, and viable sampling can differentiate Aspergillus and Penicillium. The disadvantage of viable sampling is that it takes 7-10 days to culture the sample, and the dead spores, which can also contribute to poor indoor air quality, are not counted.  Another disadvantage of viable sampling is that some mold species grow better on specific media, so the standard PDA or MEA Petri dishes may not allow all species to grow.Nonviable Sampling – Nonviable sampling documents all spores. The main advantage of nonviable sampling is the quick turn-around time. Pacific IAQ can get results next-day at no additional charge. The disadvantage of nonviable sampling is that molds are reported at the genus level, and Aspergillus and Penicillium cannot be differentiated and are therefore reported together as “Penicillium/Aspergillus”The most common samples collected are:

• Tape-Lift Surface Sample – Tape-lifts are a nonviable method of sampling where surface material is “lifted” off on a piece of clear tape. The tape is fixed to a microscope slide and analyzed through direct microscopy. Tape-lifts are quick and reliable, with very few cons. This is the most common type of surface sample collected.
• Spore-Trap Air Sample – Spore-traps are small cassettes that trap particles on an adhesive slide inside.  The cassettes are attached to a pump, which pulls a specified volume of air across the interior slide. The particles that are stuck to the slide are analyzed through direct microscopy. The advantage of spore-traps is that they are quick. The disadvantage is that they document conditions at a specific place, at a specific time, and conditions can change rapidly, especially in the outdoor air.  This is the most common type of air sample collected.
• Swab Sample – Sterile swabs are used to collect surface material. The swabs are sent directly to the laboratory where they are used to inoculate a Petri dish. The Petri dish is cultured for 7-10 days and the resulting mold growth is analyzed through direct microscopy. This type of sampling is commonly used for legal documentation.
• Anderson Sampling – An Anderson sampler is used to move air through 400 small holes, directly onto a Petri dish. The Petri dish is cultured for 7-10 days and the resulting mold growth is analyzed through direct microscopy. This type of sampling is commonly used for legal documentation.
• Bulk Sampling – Bulk sampling is the collection of bulk material for analysis. This material may include carpet samples, drywall, wood, or any other material suspected of containing mold growth. Analysis can be either viable or nonviable. This type of sampling is rarely used.
• Mycometer Samples – Mycometer is a trade name for a luminometer that quantifies mold in air and surface samples.  Mycometer detects chemical markers associated with an enzyme reaction that is specific to fungal cells. Samples are collected on swabs or PCM cassettes, and analysis is done in the field, in about 40 minutes. The obvious advantage is the 40 minute turnaround time on analysis. The disadvantage is that the results document only total fungal biomass and cannot identify specific mold genera. Another disadvantage is that there is no independent third party verification, as there is when using an independent laboratory. This means that there is no record of the results of the analysis, and no documentation other than the word of the analyst.  While the technology is promising, Pacific IAQ does not recommend the use of this product until these problems are addressed.

Sometimes many… and sometimes none! If the mold is visible and you’re looking for a remediation protocol, there’s probably no need for sampling. If the problem is not so clear cut, it may take a few samples.There is no law or regulation regarding the number of samples a consultant should take.  The industry generally relies on the “professional judgment” of the consultant. The problem with this, of course, is that you will always find someone who’s “professional judgment” differs from your own.Mold spore concentrations in the outside air are in constant fluctuation depending on the wind, precipitation, time of day, etc., and the indoor air is usually reflective of the outside air. Taking one sample inside and one sample outside would be similar to flipping a coin twice and drawing conclusions from that. Obviously the more times you flip a coin the more accurate your statistics will be. The same holds true for air sampling. It has been estimated that, in order to have 90% a confidence level in your data, you would have to take three samples and a blank from the problem area, three samples and a blank from a non-problem area, and three samples and a blank from two outdoor locations… three times a day, for three days. That’s 144 samples… No one will pay for that so we have to settle on something in between. The AIHA recommends a minimum of two outside samples and Pacific IAQ agrees. As far as inside samples, we recommend at least one in the problem area(s), and one in a non-complaint area.  For post remediation verification, we recommend two outside, one in the containment, and one outside the containment. 

There is no “good” mold to have growing in your home. Mold growth is an indication of an even larger water problem. From an environmental consultant’s perspective, the type of mold is far less important than the extent of the growth and the cause of the moisture.  The microclimates where molds develop and grow are constantly changing because of temperature, air movement, and moisture content, and the mold species that is growing right now may not be the same species that is growing next week. 

Many states now have a certification requirement for mold remediation, California is not yet one of them. Since mold remediation usually involves the removal of building materials, certain cities like Santa Rosa are requiring building permits for mold work. Permits can only be obtained by home owners and licensed contractors. So the minimum qualifications for mold work would be a general contractor’s license.There are many organizations that offer mold training and “certification”. The problem with most is that their certification is really nothing more than a training certificate. The Institute of Inspection Cleaning and Restoration Certification (IICRC), the National Association of Certified Home Inspectors (NACHI), the National Association of Mold Professionals (NAMP), and the Mold Inspection Consulting and Remediation Organization (MICRO), all offer training certifications in mold remediation and mold investigations. The problem with training certifications is that anyone can attend the 1-5 day course, pass the exam, and walk out as an “expert”.  The consumer has no way of knowing how much education and/or experience that person has.The only actual certification that exists is from the American Indoor Air Quality Council (AmIAQC). The AmIAQC certifications must pass an exam and meet stringent education and experience requirements prior to being awarded the board-certification. The Certified Microbial Remediator (CMR) certification has a two year requirement, and the Certified Microbial Remediation Supervisor (CMRS) has a five year requirement. For additional information regarding mold certifications, or to find a local certified professional, check the AmIAQ website www.iaqcouncil.org.Having said all that, there is no law or regulation that would prevent a home owner from cleaning up their own mold. Mold remediation is not rocket science and most of the “technicians” that do the actual work are seasonal or temporary employees with little or no training or experience.  If a home owner chooses to do their own remediation, Pacific IAQ recommends The Homeowners Do-It-Yourself Guide to Mold Removal, by Eric and David Keith. The book and video can be purchased at www.firstamericanresearch.com. 

In general, porous items with actual mold growth are not savable. This includes bedding, clothing, shoes, upholstered furniture and mattresses.  Porous materials with settled spores can usually be cleaned. Semi-porous and non-porous items can also be successfully cleaned, even if they have actual growth. Items that have a high monetary or sentimental value may be salvaged if the owner understands that the mold remediation may not be complete.  The owner of Pacific IAQ completed a remediation project on a 35 million dollar estate in Ross, California. The project not only included the full-gut remediation of the structure, but also the cleaning of over 30 million dollars worth of art work. Sometimes you have to get creative and step out of the box to save these special items.  

Containment is nothing more than a system of barriers and other engineering controls designed to contain the mold contamination to the designated work area.  Contractor’s typically erect 6 mil poly sheeting (visquene) around the work area and then place the “containment” under as slight negative pressure with HEPA filtered air movers. While the mold spore concentration within an area may not be too high at the beginning of a project, it will quickly climb as moldy materials are disturbed. The containment is designed to prevent those mold spores from moving to unaffected areas of your home. 

The industry is evenly split on this topic. Some consultants recommend cleaning of the duct system after remediation of any mold in your home, others believe that the ducts should never be cleaned. Pacific IAQ falls somewhere in between. We believe that actual mold growth in rigid ducts can be successfully cleaned, but mold growth in the flexible ducts is not practical or possible. Pacific IAQ recommends that flexible ducting that has actual mold growth inside should be replaced. If the ducts, flexible or rigid, are contaminated with mold spores due to an elevation somewhere in the home that has traveled through the duct system, then duct cleaning may offer some benefit. In either case it is recommended that the duct cleaning should be done by a NADCA certified duct cleaner. 

If the porous items have not been wet, and there is no actual growth, they can generally be cleaned by HEPA vacuuming. Pacific IAQ recommends that these items are HEPA vacuumed three times at opposing 60° angles. Porous items with actual mold growth are usually not salvageable. 

Semi-porous and non-porous materials can be cleaned by HEPA vacuuming and damp-wiping with a mild surfactant solution (soap and water). A surfactant actually changes the physical properties of water and acts as a solvent or cleaner. Bleach has no surfactant properties and is not considered a cleaner. 

Pacific IAQ has three requirements for post-remediation verification; the building materials must be cleaned to a dust-free condition (if there is dust and debris, then there are still mold spores), the material must be dry (below 15% moisture content), and the laboratory analysis must indicate that the air and/or surface samples are reflective of normal fungal ecology.“Normal fungal ecology” simply means that the airborne mold spore concentrations inside should be similar in species composition and distribution to the outdoor air samples.  Pacific IAQ does not necessarily require the inside concentrations to be lower than outside concentrations because outside mold spore concentrations vary from minute to minute and it takes time for inside concentrations to reach an equilibrium. We look instead for spikes, or elevations, in specific mold types that indicate a mold reservoir in the home.Surface samples are far more important than air samples. After a remediation project is complete, there should be no mold growth on the affected surfaces. This does not mean that there are no spores, as spores can be found everywhere; it means that there is no actual growth and that the mold spores on the surface are reflective of normal fungal ecology. 

NO. Mold is everywhere. Even if you could remove all of the mold from a contained area, normal mold spore levels would return as soon as the containment barriers were removed.  The goal of remediation is to fix the source of water, remove all mold growth, and clean the affected areas to a state of normal fungal ecology