The Consultant preparing the MRP should remember that air quality samples are only a snap shot in time. At best, this represents the air quality at the moment of collecting the sample. As the only guidance currently available for the consultant are publications by professional organizations and individual authors that vary greatly, the author of the MRP should decide for themselves what are the limits that best meet the needs of their client.
The MRP should specify that the Contractor provide a remediation report at the conclusion of the project. The following content of a remediation report should be placed in the project file:
The Consultant should issue a letter to the client that presents the laboratory data collected during the PRV. The content of the letter should state that, based on the visual inspection and PRV data, it appears that the contractor has completed the remediation activities in accordance with the MRP, and thus, current industry standards.
The following are actual excerpts from MRPs that were prepared by Consultants that should be avoided or clarified:
Example 1: “The HVAC system should be cleaned and sterilized.”
Comment: Using the word sterilized implies a method of cleaning that exceeds what may not be capable under field conditions, and cannot be completed on porous or semi-porous surfaces.
Example 2: “Install equipment to maintain the temperature between 50-60 degrees Fahrenheit, and the relative humidity between 40-60%, the water activity (AW) in susceptible materials should remain below 0.7.”
Comment: The requirement of pre-treating the makeup air that migrates into the containment area for temperature and humidity can be a very expensive task. This should only be considered under the requirements to preserve electronics or other sensitive items. The testing of water activity is extremely difficult under field conditions as this is normally a laboratory procedure. Field measurements of moisture content should be sufficient.
Example 3: “The negative air pressure should be maintained for at least 24 hours after the final cleaning and before PRV sampling.”
Comment: After the second cleaning of a three cleaning process, most contractors switch from using negative air pressure to using an air scrubber to eliminate the influences of the outside conditions. The MRP could discuss the time duration for having the air scrubbers operate before the testing occurs. This is normally 12 hours. There should also be a discussion of whether the air scrubbers are operating during, or turned off before, the sampling is completed.
Example 4: “The negative air pressure should be maintained at -0.02 inches of water column or greater for the duration of the project.”
Comment: There should be a range for the upper limit of pressure. Current industry standard is -0.10 inches of water column.
Example 5: "There are to be no mold spores detected in the containment area during the clearance testing.”
Comment: The absolute absence of mold spores or debris in the containment area cannot be achieved under field conditions.
Example 6: “Microbial contaminants identified indoors are equal to or lesser than the levels identified outdoors and there are no hazardous microbiological contaminants identified indoors there were not identified in the outdoor air.”
Comment: This is a common specification in MRPs and does not allow for the heterogeneous character of mold debris in the air at any given time. Because a 10 foot by 10 foot by 8 foot room contains 22,656 liters of air, and most sampling consists of 75 liters, the sampling only represents 0.003% of the room. It is not reasonable to expect a contactor to meet this specification when the consultant it limited to sampling an extremely small portion of the containment area. A tolerance above the current background should be agreed upon by the stake holders (The book titled “Bioaerosols Assessment and Control” describes tolerances above background). Also, a discussion of what is found inside the containment area, but not outside, should be tolerated and agreed upon.
Example 7: "“Pack-out all items within the residence for off-site storage.”
Comment: The requirement for the removal of all items, and for off-site storage, is not necessary under most conditions.
Example 8: “All wooden timbers should be scrubbed with an EPA approved quaternary ammonium antimicrobial agent and finally encapsulated with an appropriate product.”
Comment: It is not necessary to abate surfaces that are not contaminated with mold. Any product used to address mold contamination should focus on removing the mold colonies and not deactivating or killing the contaminate. It is not necessary to use an encapsulant (or a lock down product) as used in the asbestos industry, unless the surface cannot be satisfactorily decontaminated and the material cannot be removed.
Example 9: “The Contractor is to leave mold contamination that is less than 5 square feet”
Comment: A Consultant should never allow for mold contamination to remain after the remediation activities were completed and then expect the Contractor to successfully pass the PRV. This MRP was prepared by an engineering firm with no mold remediation experience which resulted in a very expensive law suite and delayed the project completion by months.
The purpose of the MRP is to provide guidelines for the remediation contractor to complete a project in accordance with current industry standards and demonstrate that the building can be occupied. It helps to streamline mold removal protocols and mold containment and to formulate a quality remediation plan.
Preparing a MRP with the content described herein will greatly reduce the future liabilities for the Property Owner, Consultant, and Contractor. However, the first step is for the stakeholders to find a competent Consultant.
This is Part 4 of a 4-Part series on preparing mold remediation protocols. It includes post-remedial verification, project file documentation, and examples of inappropriate protocol content. The Mold Remediation Protocol (MRP) document helps contractors follow standards and make sure the building is safe for use.
The PRV documents the successful completion of the mold remediation activities. Both visual and laboratory data complete this two-step process.
The first step is a visual inspection of the containment area look for any dust or debris. We refer to this as a white glove test. If the consultant is happy with the cleaning, a mold remediation protocol sample is taken for mold remediation protocol and sent to the lab for testing.
The number and type of samples that should be collected to complete a PRV is a topic of much discussion. At a minimum, it is recommended that non-viable air quality samples be collected. These should be collected inside the containment area and outside the building.
We also consider the building that is providing makeup air that migrates into the building. It may be necessary for the consultant to sample each unique area inside this building.
There may be up to three or four unique sources of air bing pulled into the containment area. The samples collected outside the containment are used for comparison to the mold species.
They're also compared to the population observed inside the containment. In addition, tape life samples should be collected on the surfaces that were abated (i.e. wood framing).
The MRP should also clearly state how the laboratory data from the PRV will be assessed. It should also state what will be acceptable. The consultant should remember that air is a heterogeneous medium (not homogenous). There are diurnal cycles in the production of mold spores during a day’s 24 hour period.
Further, there will be a time lag period between the changing outdoor air quality and the migration of this air into the building and then into the containment area.
The MRP should state the limitations of what the consultant will accept for indoor-outdoor differences. It should list mold species found inside the containment area but not the outside. Thus, when the laboratory data is received there will be agreement whether the contractor passed or failed.
Some consultants state that they will only accept an air quality sample inside the containment if the species and populations of mold spores are less than or equal to that found outside. However, in order to acknowledge the heterogeneous environment and lag time for equilibration, it would appear appropriate to allow an increase in the amount seen inside the containment to the outside comparison.
In addition, it would appear that a minimum amount mold spores may seen inside the containment area even though they were not observed outside at the moment the sample was collected.
At Farsight Management we understand that not all indoor air quality companies are created equal.
We feel that it is imperative to educate ourselves, our employees, and our customers. You can trust that we follow all the national standards in regards to indoor air quality. This includes mold remediation, lead abatement, asbestos removal, and everything that we do.