Mold 101: Standards, Guidelines, Clean Up, and Control!

MOLD 101: An Overview For Safety Professionals (Part 2)

By Michael A. Pinto, CSP, CMP

This is part two of the article. To read part one, click here.

Standards and Guidelines

Regardless of which sampling technique is utilized, it is difficult to find definitive standards for comparison of fungal sample results. The instruction manual that OSHA uses for its inspectors has some recommendations for indicators of indoor contamination (these are noted in colony forming units per cubic meter of air [cfu/m3]). OSHA tells its inspectors that levels of 1000 cfu/m3 or greater indoors is a matter of concern for further investigation. The American Conference of Govermental Industrial Hygenists (ACGIH) has a relatively new manual on biological contamination, but even that doesn’t have hard numbers for either cultured sample or direct analysis sample results. What most of the expert guidance documents do indicate is that comparisons should be made between out-of-doors and inside the building, and between complaint areas and non-complaint areas with the levels and types of biological organisms compared to determine whether indoor amplification is present.

The wide range of natural spore levels is dependent on the season, the surrounding vegetation, and even time of day. This fact makes the collection of out-of-doors comparison samples critical. However, these sorts of comparisons are not very helpful in determining the effectiveness of mold cleanups or even doing the risk assessment for the building occupants who have complaints about the indoor environment. In an effort to deal more effectively with such cases, a number of scientists and consultants around the country, led by Dan Baxter of San Diego, California, have assembled large bodies of anecdotal information that relates fungal counts from direct analysis samples to complaints and symptoms of building occupants. This data has pushed a number of experts to adopt 2000 counts of mold spores per cubic meter of air (c/m3) as a maximum for a clean building. Just as important as the total count, these quasi-industry standards set limits for species that are known to generate more significant allergic reactions (i.e., Penicillium and Aspergillus at less than 1000 c/m3 each) as well as species that have toxigenic properties (i.e., Stachybotrys or Fusarium are not acceptable in indoor air at any level) (ETA Internal Document).

There is some reason to be optimistic that continued studies of the relationship between airborne mold levels and health effects will eventually move the information from a quasi-industry standard to a full-fledged consensus standard and perhaps ultimately provide the basis for regulatory guidance.

Cleaning Up and Controlling Mold Contamination

Although fungus species are natural organisms found throughout the world, their presence in our houses, schools, and offices often creates health hazards that have to be dealt with in an effective manner. The key to controlling fungal growth is to remove the moisture, the nutrients, or the source of spores. In ancient times the technology was such that their only option was to try and remove the source of the mold contamination itself and pray that it didn’t return. This is illustrated quite clearly in the Biblical book of Leviticus. The priests were history’s first known mold inspectors. Homeowners with mold growth on their walls were instructed to scrape it off and then have the area checked by the priest. If successive scraping or cleaning did not keep the mold from coming back, the house was to be destroyed and the debris dumped in an “unclean” place (Bible Leviticus 14:43-45). While this may seem harsh, it does graphically illustrate that the serious health consequences of indoor mold contamination were well known over 3,000 years ago.

Source removal is an option that is used quite frequently today if visible mold growth is present on porous materials. Physical removal is still the best choice for plaster, drywall, ceiling tiles, cellulose insulation, cardboard boxes, and other such materials that harbor visible fungal contamination. In less extreme cases, removing the moisture source and cleaning the surface with a sanitizer/biocidal agent can be effective. If such techniques are employed it is essential that the sanitizing agent come in full contact with the fungal material for the required amount of time. Whether it is excess humidity, condensation or moisture intrusion as a result of roof leaks, pipe failures, or subgrade seepage, the water intrusion must be controlled. To err in either one of these critical control activities is to invite recontamination. This is why the ACGIH guidelines call for porous materials that have been wet for longer than 48 hours to be removed regardless of whether the leak came from a clean or dirty water source.

The cleanup and/or removal of fungal contamination requires appropriate work practices and personal protective equipment. Anyone who is going to intentionally disturb fungal contamination in any way should protect themselves with a respirator or filtering face-piece (minimum N-95 rating on the face-piece) (NYCDH, EPA, AIHA). Individuals engaged in a cleanup should not confuse a filtering face-piece with a dust mask, although both are now available at many hardware and discount stores. A standard mask for nuisance dust does not provide appropriate seals or filtration to minimize inhalation of disturbed spores.

When advising individuals about mold cleanups our organization recommends surgical gloves underneath cotton or leather work gloves as critical for individuals who are involved in the removal of contaminated materials. If it is cleanup and sanitizaton, heavy duty rubber gloves are necessary to protect the worker from possible chemical exposures. Large scale removal or cleanup projects may require the use of disposable body coverings, hoods, and booties to minimize the cross-contamination from work areas to clean areas in the building.

Depending on the type and amount of material to be dealt with, it may be necessary to isolate the work area from other areas in the building through the use of plastic sheeting to seal doorways, windows, vents, and other openings. If the potential for airborne dispersion of contamination is significant, it may be necessary to utilize large filtering fans to create negative pressure inside the specific work area. As such, many large mold remediation projects take on the appearance of an asbestos or lead abatment job site. Incorporating the techniques of separate decontamination stations, sealing of debris, and proper waste loadout from asbestos or lead types of projects can also be beneficial to large scale mold remediation activities.

It should be noted that there are some consultants and contractors in the restoration and mold remediation industry that feel that the precautions of work area set-up such as decontamination chambers and negative pressure are unnecessary overkill which artificially inflates the price. One of the main arguments of the “set-up minimalist” is that the mold contamination does not have the same dangerous properties as asbestos, lead, or hazardous waste. Nevertheless, continued medical research, an increasingly high level of liability associated with such work, and the practical aspects of utilizing more extensive set-up to minimize the amount of post-remediation cleaning that needs to be accomplished to reach clearance levels are factors that are pushing more and more projects toward extensive set-up.

To be sure, not every project needs full-scale asbestos-style precautions. Indeed, there are several products currently on the market that provide limited tools and supplies for homeowners and maintenance/custodial workers to properly deal with small sections of mold contamination. Even in such smaller projects the basic principles of isolation, limited dust generation during removal, thorough sanitization, encapsulation of residual mold, and proper disposal are useful.

A Parting Word

Although mold is a naturally occurring phenomenon, the presence of extensive mold growth indoors has been known as a source of concern since ancient times. Today, however, we do not have the benefit of priests trained and tasked to properly identify mold contamination and advise building owners of the proper techniques for dealing with the situation. Lacking priests to ask, many companies will be turning to their safety professionals for answers to their mold remediation questions. Hopefully this article has provided some of the necessary background to deal with those inevitable questions. For more in-depth information and advice about dealing with mold problems, safety professionals are urged to contact one of the growing number of businesses that deal with mold hazard assessment and remediation.

References

1. Bioaerosols: Assessment and Control, American Conference of Governmental Industrial
Hygienists, Cincinnati, 1999
2. Report of Microbial Growth Task Force, American Industrial Hygiene Association, 2001
3. A Guide for Mold Remediation in Schools and Commercial Buildings, Environmental
Protection Agency, 2001
4. Fungal Contamination In Public Buildings, Health Canada, 1995
5. Standard and Reference Guide for professional Water Damage Restoration S500, Institute of
Inspection Cleaning and Restoration Certification, 1999
6. Guidelines on Assessment and Remediation of Fungi in Indoor Environments, New York City
Department of Health, 1993
7. Sampling and Identifying Allergenic Pollens and Molds; Blewstone Press, San Antonio, 1990. Page 42
8. Guidelines on Assessment and Remediation of Fungi in Indoor Environments, New York City Department of Health, New York, 1993. Section 3.3
9. OSHA Technical Manual, Occupational Safety and Health Administration, Washington D.C., 1995. Page 6-9
10. Internal Document, Environmental Testing Associates, San Diego. (858) 272-7747
11. New Oxford Bible; Oxford University Press, New York, 1991. Leviticus 14:43-45

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