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MOLD RISK MANAGEMENT CRITERIA

December 5, 2002

������������ADVANCED CHEMICAL SAFETY uses the procedures and criteria described in the following to develop an opinion concerning mold and fungi in a building. Given the lack of agreement on interpreting the highly variable viable and non-viable mold data, these interpretation criteria are general and are subject to local conditions at a site, professional judgement, and a subjective assessment of the overall quality of indoor air.

������������Initially a walk through evaluation is made to attempt to identify potential sources of fungal amplification. Fungi need a source of moisture, a source of carbon, and proper temperature. Because fungi grow well at room temperature, control is achieved through adequate filtration and control of moisture. Areas which have poor filtration and a source of moisture are likely to be sources for fungal amplification.

������������A walk through investigation will look for possible sources for fungal amplification. These include: visible filamentous fungal growth, water damage, poor housekeeping, poor ventilation, and inadequate filtration. A "Mold Potential Survey" is completed to help insure a comprehensive investigation.

������������Samples may be taken. ACSafety routinely obtains viable samples in suspected locations. The samples are collected with an RCS Centrifugal sampler and allowed to grow in a certified microbiology laboratory. Viable molds are counted and reported in terms of viable spores per cubic meter of air. The three major species are usually identified. Conclusions are based on the relative concentration of viable spores when comparing indoor air to outdoor air, and the relative abundance of specific species. The following table is a guide to the interpretation of the relative concentration data.

Indoor/Outdoor Concentration Ratio	Interpretation Guide
≤ 2	Low viable spores indoors - no reason for concern
>2 - ≤ 4	Medium viable spores indoors - Control water sources and improve ventilation
>4 - 8	Moderate - Corrective action should be taken
>8	Heavy - Corrective action should be taken

������������Bulk samples may be taken from the suspect material. These may be swab samples, bulk dilution samples, or plate samples taken on sterile commercial plates. For bulk samples, the following numbers are rough rules of thumb.

Viable Spores/gram	Interpretation Guide
<10,000	Low viable spores indoors - no reason for concern
10,000 - 100,000	Medium viable spores indoors - Control water sources and improve ventilation
100,000 - 1,000,000	Moderate - Corrective action should be taken
>1,000,000	Heavy - Corrective action should be taken

The species of organisms present in a sample have a bearing on whether or not an area is considered a problem.

Attempts to link bulk sources such as visible mold on a wall to airborne concentrations of fungal organisms are often problematic. The levels of fungal organisms vary by several orders of magnitude during the course of a day due to activity levels in an area and other factors such as fluctuations in temperature or humidity which cause the release of spores. The spores may no longer be viable and though allergenic and possibly toxigenic it will not grow on any media. Rapidly growing fungi may crowd out slower growing fungi. The wrong media may be used for viable sampling.

There are at present no strict numerical guidelines which are appropriate for assessing whether the contamination in an area is acceptable or not. Further investigation of contamination sources is warranted in the following circumstances.

1. Total indoor counts are substantially greater than outdoor fungal counts (compare indoor and outdoor ratios). This comparison is not valid when the outdoor sample was taken during or immediately after precipitation. It probably is not valid during some winter months where outdoor fungal counts are usually below that indoors.

2. Comparison of indoor and outdoor levels of fungal organisms show one of the following:

A. Organisms are present in the indoor sample and not in the outdoor sample.
B. The predominant organism found in the indoor sample is different than the predominant organism in the outdoor sample.
C. A unique species of an organism is found in the indoor sample. The organism may be present in a mixed outdoor sample. It may be absent from samples taken in other areas of the building.

3. If the criteria in #2 are met and the organism is capable of producing a carcinogen (e.g., aflatoxin produced by Aspergillus flavus). The spores may be toxic by inhalation (e.g., satratoxin H in the case of Stachybotrys atra). The production of the toxin is very dependent on the source of nutrition for the organism.

4. In some cases, (especially at non-residential locations, to comply with the American's With Disabilities Act), efforts will be suggested to further reduce levels even though they are not identified as a problem in section 1, 2 and 3. This would be the case where an individual has been diagnosed by a physician to be allergic to a specific fungal organism. Efforts may then be made to further reduce exposure through increase filtration of the air. There are often problems linking an environmental exposure to an allergy test. The antigenic material produced by a fungus of a particular genus will vary according to species or a strain within the species and vary with the source of nutrition for the organism. Other factors also influence the antigenicity of the fungal spore. Thus, establishing a direct link between environmental exposure and the results of an allergy test is often problematic. Removal of the person from the area is often the most successful approach.

5. An opportunistic fungal pathogen is found in an area which houses individuals who are immune compromised.

6. Aggressive sampling and sampling of suspected sources of fungal organisms is often warranted. The amount of fungi present in an air sample is highly variable. Changes in airflow, humidity, light level and temperature can all trigger a spore release. A single air sample will often underestimate the fungal contamination in the air.

In applying the principles some additional considerations are:

A. If the numbers are high (air or bulk).
B. Fungi indoors are different from outdoors or other controls.
C. The fungi are allergenic or toxic.
D. The area is likely to be disturbed.
E. There is or was a source of water or high relative humidity.
F. There is or was a source of water or high relative humidity.
G. People are occupying this area or have contact with air from this location.
H. There are immune compromised individuals or individuals with elevated sensitivity to molds.

Note: If A through G are not true, then there probably is not a fungal related problem.

Common species that may raise the level of concern:

Absidia sp.
Alternaria sp.
Aspergillus flavus, A. fumigatus and Aspergillus sp.
Cladosporium sp.
Fusarium sp.
Penicillium sp.
Rhizpus sp.
Stachybotrys sp.