According to Encarta – World English Dictionary, “clearance” is defined as “removal of unwanted objects” and “permission for something to happen.” Both definitions are pertinent to the subject of remediation of compromised indoor environments.

Additionally, definition of another term, “remediation,” should be considered. The term is defined as “the use of remedial teaching” or “therapy to improve skills or health.” Combining all these definitions will better explain the phrase “remediation of compromised indoor environments for clearance.” Being “clear on clearance” thus becomes “The active therapy of improving compromised indoor environments by removing unwanted objects, thereby providing permission for something to happen.” In the case of remediation for clearance, that permission for something to happen is nothing more and nothing less than allowing the environment to be free to be used safely again. However, this “clearance” is not experienced as a result of the efforts by many professional’s actively attempting to clear compromised environments.

To help correct this situation, the focus of this article will be narrowed to address issues of gaining clearance indoor environments compromised by unacceptable organic contamination caused by “mold.” Clearance certainly is a major buzzword currently for remediation work within compromised environments.

We start the process of remediating mold contamination by reviewing the United States Environmental Protection Agency, Office of Air and Radiation, Indoor Environments Division document EPA 402-K-01-001 (March 2000), Mold Remediation in Schools and Commercial Buildings. This position paper lists the following six criteria for knowing when remediation and/or cleanup is complete:
We start the process of remediating mold contamination by reviewing the United States Environmental Protection Agency, Office of Air and Radiation, Indoor Environments Division document EPA 402-K-01-001 (March 2000), Mold Remediation in Schools and Commercial Buildings. This position paper lists the following six criteria for knowing when remediation and/or cleanup is complete:

“You must have completely fixed the water or moisture problem.

You should complete mold removal. Use professional judgment to determine if the cleanup is sufficient. Visible mold, mold-damaged materials, and moldy odors should not be present.

If you have sampled, the kinds and concentrations of mold and mold spores in the building should be similar to those outside, once cleanup activities have been completed.

You should revisit the site(s) shortly after remediation, and it should show no signs of water damage or mold growth.

People should be able to occupy or re-occupy the space without health complaints or physical symptoms.

Ultimately, this is a judgment call; “there is no easy answer.”
(p. 36)

Let’s analyze these general federal guidelines. The first two items are rather straightforward. Item 1 is quite clear. Completely fix the source of intrusion problem from water or moisture. In many cases, successful mold remediation efforts will involve reliance on other contractors, such as plumbers, exterior wall or window-framing carpenters, foundation or basement wall masons, or roofing specialists. Otherwise, the point-source for water intrusion will, relatively quickly, reproduce the original compromise in the environment. The same is true for HVAC systems, where failure of humidity control both within the indoor environment and within the duct system itself can perpetuate mold growth despite the best of remediation efforts.

Item 2 states that professional judgment should be enlisted to determine whether mold removal is complete. The qualifications of “professional” are assumed in these guidelines, but the situation in practice sometimes involves personnel who lack the specialized knowledge, academic studies, and practical training to discharge their duties from the required perspective. After all, “judgment” involves forming an opinion by discerning and comparing, a duty made all the easier by actually being a professional. Obviously visible mold, mold-damaged materials, and moldy odors should not be present. However, in many cases now encountered (as a result of energy-efficient strategies in construction), professional judgment will involve and rely on deeper probing of obscured spaces and of areas proximate to the obvious problems in order to be clear on clearance.

With respect to Item 3, where remediation should reduce the sampling counts of molds, the federal guidelines further delineate the following:

“Sample analysis should follow analytical methods recommended by the American Industrial Hygiene Association (AIHA), the American Conference of Governmental Industrial Hygienists (ACGIH) or other professional guidelines (see Resources List). Types of samples include bulk samples (chunks of carpet, insulation, wall board, etc.) and water samples should be taken from condensate drain pans or cooling towers”
(p. 25).

On the surface, this is relatively good instruction. However, when considering outside levels compared to those found indoors, how would you factor in the obvious issues of relative humidity, ambient temperature, and air velocity? When you consider the relationship of temperature, moisture, and air velocity, just where you set the “baseline”? Just how do you begin to construct a workable interrelationship of these factors, to best utilize your professional judgment?

Item 4 reflects basic good business discipline, revisiting the remediated environment shortly after the project is completed, to confirm that the intended result has been accomplished: no signs of water damage or mold growth.

Item 5 also confirms the intended result, namely that people should be able to be in the space without generating health complaints or physical symptoms. What steps should you take, in exercising your professional judgment, to insure safe re-occupancy? For example, to what extent do you need quantifying pre-remediation testing, for comparison to post-remediation samples? The liability and duty for responsible exercise of professional judgment come crisply into focus when your determination is expected to reliably predict whether the job has been completely done.

When we address Item 6, we have come full circle: the final criterion for knowing when remediation and/or cleanup is complete “ultimately … is a judgment call; there is no easy answer.” If there is no easy answer, then what are all the difficult issues that you should be weighing and comparing in reaching your final opinion. Since these factors are not listed in the guidelines, exactly, who is relied upon for “professional judgment” provides an enormous amount of ambiguity in the issue of clearance?

Let’s continue our educational inquiry and visit our next document, the New York City Department of Health, Bureau of Environmental & Occupational Disease Epidemiology: Guidelines on Assessment and Remediation of Fungi in Indoor Environments. Environment Assessment, 2.4 Analysis of Environment Samples states:

“Air samples should be evaluated by means of comparison (i.e. indoor to outdoors) and by fungal type
(e.g. genera and species).

In general, the levels and types of fungi found should be similar indoors (in non-problem buildings) as compared to the outdoor air. Differences in the levels or types of fungi found in air samples may indicate that moisture sources and resultant fungal growth may be problematic.”

The ambiguity of this guideline could be misinterpreted by almost anyone when trying to gain clearance. The relationship of temperature, relative humidity (moisture), and air velocity all will affect the definition of baseline data, which then skews your efforts at comparing outdoor to indoor measurements.

Further, we should focus on the American Conference of Governmental Industrial Hygienists (ACGIH), Bioaerosols – Assessment and Control. Section 15.5, Judging Remediation Effectiveness, states – “the success of a remediation effort is judged in part by the visible degree of contaminant removal that is achieved. Effectiveness may also be confirmed by sampling” [see 15.2.3.4]. The qualifying words “in part” and “visible degree” and “may also be” are proper in a guidelines document – but again, they allow for a broad range of ambiguity in understanding and, therefore, in end results. While we would like to think that everyone performs to the highest standard, real-world activities simply fail to meet the test. Just how clear are you on gaining clearance? That is the standard to which you will perform and by which you will judge your success.

If performances and end results differ, then one likely explanation is that training in the remediation field has yet to address the issue of clearance in a clear and unambiguous fashion. The ultimate criterion for the adequacy of abatement efforts in the treatment of all biological and chemical contaminations (not just mold) is the ability of people to occupy or re-occupy the space without health complaints or physical discomfort [see 8.6.3]. This is, as we discussed before, a predictive professional judgment. Complicating this situation is the gnawing realization that not one of the guidelines provides a discrete standard, firm guidance on how to form your opinion by discerning and comparing the key factors involved. Again, possibility of referring to a minimum performance level concerning clearance is hindered by ambiguity in the relationship of relative humidity, ambient temperature, and air velocity, especially as these relate to indoor and outdoor comparisons.

While we applaud the guidelines above for the level of information they provide, unfortunately, the interpretation of individual professional judgment leads to cloudy not clear results. Understanding the method by which federal standards are developed, such guidelines are the important initial step toward standardization. However, when remediation is attempted within compromised environments, interpretations of such general guidelines vary greatly among individuals and across region, making consistent clearance difficult to rely upon.

In summary, clearance is based upon professional judgment of an individual who should be qualified – by study, training, and actual practice — to issue such a mandate. Clearance should never be based solely upon subjective standards such as visual inspection alone. Whenever feasible, clearance should be quantified by accepted scientific methodologies. When necessary, even “experimental” techniques should be employed as part of the assessment, to give the broadest information in making the predictive judgments regarding the safety of re-occupancy. Scientific methodologies should encourage development of a more distinct relationship between ambient temperature, relative humidity, and air velocity, specifically when comparing indoor to outdoor data.

Additionally, we urge you to consider how the extremes of outdoor variability in temperature, relative humidity, and air velocity can challenge and even cripple reliance upon comparative values. The guidelines recommend pre- and post-remediation comparisons of indoor-to-outdoor levels while ignoring the many obvious variables that can skew interpretations. Indeed, it is easily possible to claim clearance when that standard has not yet been met.

Understanding the concepts and having a working knowledge of these relationships will allow the indoor air quality professional to better exercise professional judgment with remediation projects of compromised environments. Based upon these ideas, recommendations for clearance in remediation projects include the following:

  1. Is a qualified air quality professional setting the written clearance guideline?
  2. How was this clearance guideline derived?
  3. Were considerations for ambient temperature, relative humidity and air velocity taken into consideration in setting the clearance guideline?
  4. Is the recommended clearance guideline realistic with regard to the variability’s of temperature, humidity and air velocity?
  5. Have the clearance guidelines been clearly written into the scope of work for remediation?
  6. Have you relied clearly and comfortably on your professional judgment with assessment of the remediation process, to gain clearance?
  7. Have you obtained written copies for your files of the final documentation of clearance reports assembled by the air quality professional at the completion and any subsequent follow-up evaluation visits to the remediated environment?
  8. Are you unclear about anything on gaining clearance? Don’t be afraid to ask questions EVER! Remember, your professional judgment is the final determination upon which people will rely when they re-occupy the environment that you have remediated.

The industry of remediating compromised indoor environments is dealing with critical ambiguities on this topic of gaining clearance. We share an optimistic opinion, based upon the realities of the political and regulatory processes and on our own remediation experiences that industry-wide standardization and specific guidelines will soon be forthcoming in our industry. Our public not only demands that we be clear on clearance – they deserve nothing less from any of us.

About the Author:

JL Skiter Kowalski, CAFS, CMR, CIE, PIAQM is a NAFA Professional Member and has been involved in the air filter industry for over 20 years. Credit also goes to John Parks Trowbridge, M.D. and Debra A. Troxclair, Ph.D. in the development of this article.

Clear on Clearance; Spring 2003 issue of Air Media
Author(s): Skiter Kowalski, CAFS, CME, CIE, PIAQM