Investigation of air quality problems is a difficult task requiring detailed knowledge about the affected environment, possible contaminants sources and most of all it requires an open mind to be able to spot potential problem areas. I have been asked to investigate possible indoor air quality problems in an Oxford college after one of the members of staff complained about poor indoor air quality in one particular computer room. The room with alleged air quality was located in the basement and was approximately 5m wide X 5m long and 2.4m high. The rooms was used as a computer working room for students who visit the room on “as needed” bases. The room was equipped with 12 computer stations.
The location of the room was not particularly fortunate because basements are not designed for continuous human occupation. It is likely that anybody requiring working in a basement would sooner or later complain either of poor air quality or lighting or both. Unfortunately as any space is at the premium school and business must make use of any available resource they have. Have carried out a thorough inspection of the computer room and did not found any problems with moisture which could lead to odours of mould contamination.
Fortunately I have managed to find another but better positioned computer room of virtually the same size and use frequency which I could used as a comparative bases for my assessments. I have decided to measure a range of volatile organic compounds, formaldehyde and fungal spores in both rooms and in the outside environment to evaluate if a significant difference exists between them.
The measurements of volatile organic compounds showed that the problem room has a overall concentration of VOC of 17 µm/m3 and the non-problem computer room had VOC concentration of 42 µm/m3. Similarly the overall concentration of aldehydes in the problem room was 36 µg/m3 and in the non-problem area was 66 µg/m3. More specifically the concentration of formaldehyde gas in the problem room was measured at 26 µg/m3 and in the no-problem room at 45 µg/m3.
The moulds spores sampling showed that at there was significantly lower concentration of mould spores in the problem-room in comparison to the external environmental background sample and the non-problem area sample. Mould genera evaluation of the problem room samples show that the most dominant genera Penicillium/Aspergillus type of spores. The collected environmental background and non-problem area samples were dominated by Cladosporium spores and a group of unidentified fungal spores.
Viable mould samples showed that the overall concentration of viable mould spores in the problem room was only marginally elevated in comparison with the background environmental samples. The overall concentration of viable mould spore samples indoors ranged between 994 and 1450 colony forming units per cubic meter. The average background concentration of culturable fungal spores in the atmosphere at the time of the assessment was 1120 colony forming units per cubic meter.
Probably the most significant factor affecting the indoor air quality in this room was the ventilation. The room had one low level window for provision of fresh air supply. The window was locked and could not be open to provide fresh air during times of high occupancy. There was one air conditioning unit fitted in the ceiling of the room. The air conditioning unit does not provide fresh air into the area.
In the end I have concluded that based on the results of moisture mapping, visual observation and microbiological sampling and identification it was my opinion that the most likely reason for adverse health symptoms experienced by some of the employees in the problem room was lack of fresh air supply.
By Tomas Gabor