Just before the start of winter I was invited by the management of large hospital in the north of the country to investigate a case of poor indoor air quality in a small office building. The office workers have been complaining from a poor indoor air quality for several months. They suffered from throat irritations and increase frequency of illnesses, generally respiratory in nature. My investigation has as usual started with the inspection of the building as such. As you can see from the photo below one corner of the building is under the level of the ground to a height of about 1 meter.
Building corner below ground level
The build was constructed in 1970′s and had a damp proof course installed. Even though it is not visible in the next photo the damp proof course lays about another 10 cm into the ground.
This is a classic example of a damp proof course failure through bridging. The soil around the building has bridged the existing damp proof course and the water from the ground was allowed to penetrate the building single leaf brick wall. As is it common for rising damp, the problem manifested itself on the inside by paint wall damage to about a meter height. This kind of damage can go high depending on the height of the external ground and wall materials.
Water damage to internal wall from water penetration
Naturally, the penetrating water has caused a significant increase in internal humidity. Water condensed on internal windows and walls of the office. Employees working in this office already concerned by the visible damage, stuffy humid air and visible mould have started experience respiratory problems.
I have carried out sampling of the office air and carried out evaluation of the mould spore burden. Our analysis showed that the concentration of mould spores in the building was about 1700% higher as corresponding mould concentration on outside of the building.
- Mould contamination of office window
The microscopic identification of moulds on the window and in the office air has confirmed the presence of several penicillium species, Cladosporium and Paecilomyces mould.
None of these moulds is considered particularly hazardous to health, or at least not pathogenic in human but it is well know that exposure to large amount of any mould spores is likely to result in allergic reactions and /or respiratory problems.
The proposed solution to this problem was to carry out complete deep clean of the property to reduce the mould spores levels to normal concentration and remove the ground about the perimeter of the building. This would stop the rising damp problem and subsequently mould would not have enough moisture to establish itself again.
As it goes for government own properties the building was demolished – so much for money saving subtle approach.
By Tomas Gabor
