| Table 1 : Samples | Conclusions |
| Table 2 : Remediation # 1 | Photos, Remediation # 1 |
| Table 3 : Remediation # 2 | Photos, Remediation # 2 |
INTRODUCTION
This article describes the results of monitoring the exposure of remediation workers to airborne fungal spores during two mold remediations. Both remediations were performed inside full containments; and by the same remediation company. The measured concentrations of airborne fungal spores are reported for personal samples, inside area samples, and outside area (decontamination unit) samples. The sampling method is described, the sample results for each remediation are presented, and the sample results are discussed. In addition, photographs of the remediation, personal sampler, and the samples themselves are included in the article.
Until recently, the technology to allow mold remediation workers to be monitored for exposures to airborne fungal spores has not been available. Therefore, almost no data are available on typical exposure levels inside a contained work area. The author is not aware of any other published data describing the personal exposure of mold remediation workers.
If a sufficient database of worker exposures is established, then the appropriate level of respiratory protection may be assessed. Second, the potential for remediation activities to contaminate areas outside containment may be evaluated. Third, work practices that minimize exposures may be identified.
The sampling media were Bi-Air cassettes containing 25 millimeter (mm) diameter mixed cellulose ester (MCE) filters with a pore size of 1.2 microns (um). The cassettes were designed to operate at airflow rates of 0.4 to 4.0 liters per minute (lpm); and for sampling times of up to six hours in ambient environments. The cassettes used to collect area samples were equipped with a slotted cap, while the cassettes that were used to collect personal samples were equipped with a three-hole insert.
The samples were collected using SKC 224-PCXR8 Universal Sampling Pumps. These low-volume pumps have an airflow range of 0.005 to 5.0 lpm. The airflow rate was verified using a 65 mm constant bore rotameter with a range of 0.2 to 4.0 lpm, which was attached to the cassette cowl by a Bi-Air calibration probe.
Remediation # 1 involved the removal of contaminated drywall inside a containment with an approximate size of 8 x 10 x 10 feet. A low-volume HEPA filtration unit was operating inside containment in the scrub mode. The work was performed by three workers wearing personal protective equipment and full face respirators. Only the first two hours of the remediation were monitored. Three two-hour samples were collected at an airflow rate of 1.0 lpm: an outside area, and inside area, and a personal sample. The outside area sample was collected at the entrance to the decontamination unit of the containment.
Remediation # 2 involved the removal of contaminated drywall inside a containment, although the size of the containment was not reported. The work was performed by workers wearing personal protective equipment and full face respirators. Other details were not reported.
A total of three personal samples, four inside area samples, and one outside area sample were collected during the first two hours of the remediation. The approximate sampling time for each inside area sample and personal sample was 30 minutes. The outside area sample, which was collected at the entrance to the decontamination unit of the containment, was collected for the full two hours.
| First Personal | 0921 | 0936 | 15 |
| First Inside Area | 0921 | 0951 | 30 |
| Second Personal | 0958 | 1028 | 30 |
| Second Inside Area | 0955 | 1025 | 30 |
| Third Inside Area | 1030 | 1055 | 25 |
| Third Personal | 1105 | 1126 | 21 |
| Fourth Inside Area | 1103 | 1133 | 30 |
| Outside Area | 1021 | 1221 | 120 |
Airborne samples were collected at 1.0 lpm for two hours. The concentrations of airborne fungal spores detected in the samples collected during Remediation # 1 are contained in Table 2.
| Ascospores | 100 | 0 | 500 |
| Aspergillus/Penicillium | 0 | 3,300 | 1,400 |
| basidiospores | 400 | 0 | 0 |
| Chaetomium | 0 | 13,800 | 15,800 |
| Cladosporium | 5,000 | 60 | 200 |
| Stachybotrys | 0 | 100 | 2,100 |
| TOTAL | 7,500 | 17,800 | 20,000 |
The sampling period of two hours (sample volume of 60 liters per sample trace) resulted in a heavily overloaded filter for the personal sample. The overloading on the inside area sample was to a lesser degree, but still problematic. The reported spore counts for both samples were assumed to be significantly less than the true counts. Therefore, it was concluded that sample volumes significantly less than 60 liters should be used to monitor the exposures of mold remediation workers.
The heavy debris on the filter samples was reminiscent of the early days of asbestos, when the workers were not as concerned about the airborne concentration of fibers inside containment. They used very aggressive methods, often without misting, and were not overly concerned with keeping the workspace clean. The sample filters collected under those conditions were often heavily overloaded with debris - very similar to these results. However, as the industry became more sophisticated and work practices evolved, filter samples overloaded with debris were encountered much less frequently.
The Bi-Air cassettes were changed more frequently during the second remediation that was monitored. The sample times for the inside area and personal samples did not exceed 30 minutes, although an airflow rat of 1.0 lpm was still used. The shorter sample times and reduced sample volumes of 10 to 15 liters did improve sample quality, although overloading was still an issue. However, the ability to analyze these samples was greatly improved compared to those collected during Remediation # 1; and one can have greater confidence in the reported sample results.
The concentrations of airborne fungal spores detected in the samples collected during Remediation # 2 are summarized in Table 3. However, only the concentrations of Aspergillus/Penicillium, Chaetomium, Stachybotrys, and total spores have been included in Table 3. In addition, the sampling periods for the inside area and personal samples have been matched as closely as possible.
| First Personal | 2,130 | 1,330 | 6,130 | 14,660 |
| First Inside Area | 0 | 240 | 720 | 2,640 |
| Second Personal | 0 | 1,200 | 6,800 | 9,460 |
| Second Inside Area | 800 | 600 | 3,600 | 7,800 |
| Third Personal | 0 | 570 | 14,850 | 21,500 |
| Fourth Inside Area | 0 | 0 | 4,950 | 5,270 |
| Outside Area | 267 | 0 | 0 | 5,100 |
The Aspergillus/Penicillium type spores detected in the outside area sample, located outside the entrance to the decontamination unit, had a smooth surface while those detected in the inside area and personal samples had a rough surface - not the same spores. Therefore, it was concluded that the containment was effective in preventing the spread of contaminant spores outside of the contained work area.
The concentrations detected in the inside area samples were generally less than those in the corresponding personal samples. For example, the average exposure based on the Inside Area samples was 5,240 spores/m³, while the average exposure based on Personal samples was 15,210 spores/m³. Therefore, in general, the spore concentrations detected in the inside area samples were not representative of personal exposures.
The concentrations of airborne fungal spores inside the contained work area were again relatively low. The maximum concentration of total spores was less than 22,000 spores/m³. Although the author has detected concentrations in that range in occupied spaces, furnishings exposed to those concentrations were found to beeither contaminated or colonized. Therefore, these preliminary results suggest that containments are required for mold remediation.
The Bi-Air cassette did allow the exposures of remediation workers to airborne fungal spores to be monitored. However, significant overloading of the filters with debris occurred when using the sampling parameters employed in these studies.
Work practices were typical of the early days of asbestos, when the concentration of airborne debris inside containment was often excessive.
No contaminant spores were detected in either sample located just outside the decontamination unit. Therefore, both containment's were effective in preventing the spread of contamination.
The concentrations of airborne fungal spores detected inside containment using the reported sampling parameters were relatively low, with a maximum reported concentration of total spores of less than 22,000 spores/m³.
The preliminay results suggest that containment is required when performing mold remediations.
The results obtained during Remediation # 2 (improved sample quality) suggested that the concentrations detected in Personal samples were higher those in the Inside Area samples by a factor of 3 to 1. Therefore, inside area samples did not provide a good estimate of personal exposures.
Sample volumes of less than 10 to 15 liters are required to monitor worker exposures, assuming current work practices.
1. Containment
2. Contaminated drywall
3. Low-volume HEPA scrubber showing location of Inside Area sample
4, 5, 6.Bi-Air Cassette used as a Personal Sampler on a remediation worker.
7. Outside Area Sample
8. Worker inside containment wearing pump
9. Detail of the Inside Area sample cassette
10. Chaetomium spores in heavy debris, 600X
11. Stachybotrys like spores in heavy debris, 600X
12. Chaetomium and Aspergillus/Penicillium like spores, 600X 13. Aspergillus/penicillium like spores, 600X
13. Background debris was not as heavy, and spores were much easier to see.
14. Air bubbles trapped in the debris were a problem, and required gently heating the slides to prevent them from interfering with the analysis.
15. Chaetomium spore
16. Two Stachybotrys like spores; lighter background debris.