Sampling for Mould in Red Bluff Elementary School, Quesnel

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1 Sampling for Mould in Red Bluff Elementary School, Quesnel Introduction What are moulds? Moulds are part of the fungi kingdom and serve an important role in breaking down organic matter. They are found both outdoors and indoors. The fungi most commonly found growing indoors are often called "moulds" (for example, species of Penicillium, Aspergillus, and Cladosporium). Moulds spread naturally through the release of spores into the air. Any air movement will cause the dry spores to be carried with the air current; eventually the spores will land on a surface. Moulds may also spread through direct mechanical transfer of mould-covered materials, or by a person or animal brushing against a mould and then depositing some mould on another surface. Once a colony of mould is established and subsequently disturbed or damaged, spores may become airborne and spread throughout the building. As long as moisture and nutrients are present, mould growth will usually continue unabated. Moulds are likely to grow where there is water or prolonged dampness - such as in bathrooms, crawlspaces, water-damaged walls, ceiling/roofing material, and the damp parts of refrigeration or air conditioning systems (for example, air chillers or drip trays). A source of nutrients for mould is basically any organic material and can include simple sugars and starches as well as more complex carbon-containing substances such as paper and wood. Many porous building materials such as drywall, wallboard, wallpaper, insulation, ceiling tile, and wood contain organic material. Without moisture, mould cannot grow or reproduce and will die or enter a dormant stage. In the case of some moulds, this dormant stage can last for years. However, given the right conditions, such as a water or moisture supply, the mould can become active (start growing again) and release spores. Nature of the mould problem within the school A previous mould assessment, conducted in 2012 by an independent health and safety consultant, identified mould contamination within the crawlspace at Red Bluff Elementary School. In addition, standing water was present on the crawlspace floor in a number of locations. At that time, the concentration of mould spores measured in the crawlspace was 100,000 spores per cubic meter (spores/m 3 ) and most of these were Penicillium/Aspergillus spores. Staff in the school had reported a number of health (and other) complaints ranging from musty odours to upper respiratory allergy-type symptoms and even the onset of asthma. 1

2 The School District conducted some mould remediation within the crawlspace, including the removal of suspected mouldy debris, sealing of mechanical penetrations from the crawlspace into the classrooms, and the installation of a ventilation system designed to maintain the crawlspace at a lower air (negative) pressure than the rest of the school. This would act to prevent the exchange of air between the crawlspace and the remainder of the school. According to school staff, the ventilation equipment in the crawlspace had not been set up properly and continued to push air from the crawlspace into the school. The purpose of the present sampling was to determine if mould from the crawlspace had migrated into the school and could still affect the health of school staff. Sampling Methodology Five locations were identified for dust sampling as summarized in the following table: Sample Location Number Room 3, carpet Room 3, shelving Room 9, Aboriginal room, carpet Gym floor, by the crawlspace hatch Crawlspace floor Dust samples are a more reliable indicator of ongoing mould contamination than other sample types as they represent an accumulation over time, rather than a temporary condition. In contrast, airborne mould spore concentrations can vary greatly, depending on many factors, and can change daily or even hourly. Dust samples were collected by a WorkSafeBC Occupational Hygiene Officer, on June 27, Samples were collected using a vacuum cleaner equipped with dust collection attachments and filters, provided by the analytical laboratory. Samples were analyzed by EMSL Analytical, Inc., in New Jersey, in accordance with the ERMI sampling methodology. ERMI stands for Environmental Relative Mouldiness Index. The technique was developed by scientists at the US Environmental Protection Agency to help predict mould contamination within US homes and other buildings. In order to determine a mouldiness index, the dust samples are analyzed for the presence of particular mould species using DNA (genetic material) detection techniques that don t depend on spore traps or culture. The method can identify up to 36 different species of moulds, including 26 that are associated with water damage/mould contamination and 10 species that 2

3 are typically found outdoors. A mathematical comparison between these two groups results in a mouldiness index. Index numbers of 5 or greater indicate that water damage/mould contamination may be present (see the Figure below). The technique can also be used to identify the presence of moulds from a contamination source that may have migrated to other areas within a building. Individual species can be traced using this method. Results ERMI mouldiness index The results of the ERMI index calculations are shown in the following table. Sample Location ERMI Index Number Room 3, carpet Room 3, shelving undetermined Room 9, Aboriginal room, carpet Gym floor, by the crawlspace hatch Crawlspace floor 16 Other than the crawlspace, the ERMI index values were far below the cutoff value of 5. This suggests that mould contamination from water damage is not present in these samples. Most of the moulds identified in the classrooms and Gymnasium were common outdoor species. The index value from the shelving in Room 3 was undetermined, as very few moulds (of any type) were detected. In contrast, the crawlspace index was very high and indicates that mould contamination is still present in the crawlspace dust. 3

4 Mould species identification results The results of the identification, to species, of the water damage indicator moulds are summarized in the following table. Water damage indicator moulds Identified in the classroom dust Water damage indicator moulds identified in the crawlspace dust Room 3 Carpet Room 3 Shelving Room 9 Carpet Gym Floor Aspergillus penicillioides Yes Yes Yes Aspergillus restrictus Aspergillus versicolor Eurotium (A.) amstelodami Yes Yes Aureobasidium pullulans Yes Yes Yes Cladosporium sphaerospermum Yes Penicillium brevicompactum Yes Yes Penicillium corylophilum Penicillium variabile Yes Scopulariopsis chartarum Yes Stachybotrys chartarum Wallemia sebi Yes Yes Yes Of the 26 species of moulds that were analyzed as part of this technique, 12 were identified in the crawlspace (see the table above). Of these, the most numerous were Aspergillus penicillioides and Wallemia sebi (highlighted in the table). Many of these moulds were also found in the classroom and Gym floor dust samples. In particular, A. penicillioides and W. sebi were found in all of the floor dust samples collected. The dust sample collected from the shelving in Room 3 contained no water damage indicator mould species. The original 2012 consulting report identified significant amounts of Penicillium/Aspergillus type spores in the air within the crawlspace and the school, as well as spores of Stachybotrys (a mould commonly associated with water damage). Given the results of the present dust sampling, it is likely that the Penicillium/Aspergillus spores detected in the original spore traps were Aspergillus penicillioides (and other similar) spores originating from the crawlspace. A complete set of the laboratory results have been included with this report. 4

5 Conclusions and Recommendations The results of the dust sampling indicate that the classrooms and Gym are not currently contaminated with mould due to a past exchange of air with the crawlspace. However, there is evidence, in the settled dust, that the mould within the crawlspace has migrated into the occupied areas of the school. Given the amount of mould contamination in the crawlspace and the complaints reported, it is likely that, at some point, the airborne mould spore levels in the classrooms were high enough to affect the health of the school staff. These levels would have depended on the amount of mould in the crawlspace air (as high as 100,000 spores/m 3 ), how much crawlspace air moved into the school and the number of time this took place. In order to prevent any additional mould from entering the school from the crawlspace and eventually address the crawlspace contamination problem, the following are recommended: All of the flooring in the school should be vacuumed using a HEPA vacuum cleaner. This vacuuming should be performed on a regular, ongoing basis. Access to the crawlspace should be restricted to properly trained workers using the appropriate engineering controls (e.g., containment around the crawlspace hatch during entry) and personal protective equipment (including respiratory protection). The ventilation system in the crawlspace should be continuously operated in negative pressure mode, as long as there is moisture in the crawlspace. The water intrusion problem in the crawlspace should be investigated and corrected. Geoffrey A. Clark, MSc, CIH, ROH Sr. Occupational Hygienist WorkSafeBC 5