Damp and mould growth history in the property
In this article we will discuss our recent visit to a library based in Leeds where we were requested to carry out an assessment of indoor air quality in relation to selected biological contaminants. The library, a period three storey town building is situated in the busy city centre. The building consists of a basement used for the storage of books and upper floor areas used as a main public library. The basement consists of 8 individual book storage areas and several ancillary rooms. Individual areas are open and connected to each other which allows the free flow of air throughout the book storage areas. The building has a long history of damp and mould growth in the book collections. Due to this the basement area had been fitted with air-conditioning and dehumidification equipment and walls had been treated, repaired and tanked to control the ingress of water in to the basement all prior to our assessment.
Sampling and analysis of the indoor air quality
Our surveyor collected samples of airborne moulds onto Vesta Spore Trap cassettes using High flow 1600 air sampling pump. These samples were collected over a period of ten minutes and total volume of 200-250 litres was collected. Samples of airborne viable moulds were also collected by an SKC biostage 200 sampler using a High Flow 1600 air sampling pump. Samples were collected onto 90mm microbiological growth plates with ME or SD agar medium. Our surveyor then used a process called Moisture mapping using specialist equipment called a Hydromette HB30 moisture meter and a Tramex Moisture Encounter Plus. The wind speed was also measured with a Rotating Vane Anemometer LCA301.
Our conclusions and recommendations based on Moisture mapping
Based on the results of the moisture mapping and the samples collected, our surveyor concluded that the library basement was affected by visible mould and significantly elevated levels of fungal spores.
The indoor air in the basement is affected by elevated number of Aspergillus mould spores. Aspergillus moulds in general are considered highly allergenic and pathogenic and are the cause of the respiratory disease called Aspergillosis. The fungal contamination in the basement is limited to the outer surfaces of books and the total extent of fungal contamination is approximately 10m2. The assessment of all the relevant exposure factors indicate that at the present the overall risk to health from exposure to fungal elements in the basement is likely to be medium to high.
Our surveyor strongly recommended the client to use respiratory protection of FFP3 when carrying out work in the basement for long periods of time. It is also recommended that individuals with pre-existing respiratory illnesses, individuals with respiratory allergies and otherwise immunocompromised individuals avoid work in the basement. The ventilation rate in the basement should be increased in order to aid the drying, decrease humidity and provide fresh air into the basement essentially preventing damp and mould growth in the future.