Mould investigation and employees exposure evaluation in Leeds

In this article, we take a look at a local library we were called to evaluate and certify safe for occupation. After evaluating the general state of the building, looking at the level of fungal contamination and conducting microbiological analysis, we identified that the air quality in the basement bookstores was poor with respect to fungal spores. Unfortunately for the staff, the risk to health from exposure to fungal spores is high when working with contaminated articles for significant periods of time. As part of our solution, we recommended that the owners provide a fresh air supply in the basement in order to dilute the contaminants. A supply of fresh air would ensure that humidity conditions were regulated so as to prevent fungal growth.

The library, a period three-storey town building was situated on ground level in Leeds. The building has had a long history of damp and mould growth, particularly in the book collection area. The building was surrounded by properties of similar construction and use. The basement area was fitted with air-conditioning and dehumification equipment, with walls treated, repaired and tanked to control the ingress of water in to the basement.

moulds survey and air quality evaluation in leeds

Mound Sampling and Analysis 

In order to assess the indoor air quality, we collected samples of airborne moulds onto Vesta Spore Trap cassettes, using a high flow 1600 air sampling pump. We calibrated sampling flow rates before and after sampling with an FW 1 working flow meter. In addition, samples of airborne viable moulds were collected with a SKC biostage 200 sampler using a High Flow 1600 air sampling flow meter. For our damp inspection, we carried out moisture mapping using a Hydromette HB30 moisture meter and Tramex Moisture Encounter Plus.

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Mould Exposure Results Evaluation 

The non-viable spore trap samples we took showed that at the time of the assessment the overall concentration of airborne fungal spores in the basement was lower than the existing environmental background. However, many areas in the basement showed elevated spore counts in comparison to the rest of the building and external environment. The spore trap samples collected in the basement were dominated by Penicillium and Aspergillus type spores.

Our analysis revealed that the overall concentration of non-viable fungal spores and distribution of fungal genera in samples was indicative of indoor sources in the basement. Penicillium and Aspergillus spores are closely associated with water damage in buildings and are considered to be allergenic.

Mould Exposure Conclusions

The library basement was the main problem area of the property, with elevated fungal spores, visible mould and air dominated by Penicillium and Aspergillus spores. On the books, we took surface samples that indicated that Aspergillus brasilensis was on the surfaces of the books. This indicates that the basement is likely to have a greater number of species present than indicated by microbiological analysis. Aspergillus moulds can be a problem in large quantities, as they are highly allergenic and pathogenic. In fact, Aspergillus moulds are the cause of a respiratory disease called Aspergillosis.

Based on our mould survey and damp inspectionit is our opinion that the indoor air quality was significantly affected by fungal spores, although none of the employees working in the practice can be considered at an increased risk to health due to personal circumstances. However, if left unaddressed the overall risk to health from exposure to the fungal content in the basement is medium to high. In future, we recommended the user of respiratory protection of FFP3 when carrying out work in the basement for long periods of time. In addition, we recommended that the owners increase the ventilation rate in the basement to aid drying, decrease humidity and provide fresh air.

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