Office environments are places which often suffer from indoor air quality problems. The reasons for poor air quality can range from insufficient fresh air supply, poor air filtration, off gassing from furniture and fittings, contaminants introduced by maintenance or cleaning personnel, building services failures, contaminants introduced by occupants them self, computers, photocopiers and many others. The multitude of potential reasons for complaints can sometimes be overwhelming and finding a solution to the problem is a very complex task.
Each investigation into air quality in the office environment starts with a thorough review of the existing situation including review of the building plans, maintenance schedules, unusual events in the building life (flood, fire), discussion with the maintenance operatives and most importantly discussions with the complaints them self. This data gathering exercise is possibly one of the most important parts of an indoor air quality investigation because it provides the investigator with information about possible sources and thus the selection of most appropriate investigation, sampling and analysis methods. No investigator holds all the equipment and can employ any sampling protocol and he/she certainly cannot analyse for any chemical customer might wish for.
Many customers have often unreasonable expectation from an investigation and often expect the investigator to turn up, sample something and simply tell them what the problem is and how to resolve it. I wish it was that simple in all cases! The investigator has to approach every investigation with a completely open mind and do not get sidetracked by opinions of the building managers or occupants. All information regardless of who provides it is extremely important and any piece can lead to a solution but open mind is the best tool in any indoor air quality investigation.
I have been invited to investigate an indoor air quality problems occurring on one floor of a relatively modern office block. The occupants have been complaining from poor air quality, increased frequency of illness (mainly respiratory) and odours. The office has previously suffered from a small water leak which has originated on the floor above. The leak was caused by a failure of a window frame which allowed the water to penetrate the building envelope and leak through the floor. The water has caused a relatively small brown staining on the suspended ceiling tiles. After the appearance of the staining the frequency of air quality complain increased and mould have been suspected to be the main reason.
At the request of the client several air quality tests including mould spore sampling and identification, formaldehyde test and volatile organic compounds screen were performed. In addition to these test direct reading samples were collected for the presence of ozone, suspended particulate matter, carbon monoxide and forensic dust analysis.
The chemical analysis of the indoor air showed that the total concentration of aldehydes, including formaldehyde, was measured below 60 µg/m3 and none of the identified compounds exceeded its occupational or indoor air quality concentration limit. The total concentration volatiles organic compounds was measured below 20 µg/m3 and all the compounds could either be associated with personal care products, traffic or off-gassing from furnishing. However the concentration of volatiles in the environment was very low and very unlikely to be the source of the complaints. Ozone and particle counts did not show any abnormalities which could be source of the complaints.
The analysis of the fungal spores concentration showed that the concentration of spores and other fungal elements in the air was significantly lower indoor than in the outside environment; with existing mould genera consistent with the fungal genera present outdoors. The mould spores primarily considered to be the main source of the complaints turned out to be in norm and unlikely to be the problem. The indoor amplification of fungal spores has not been confirmed.
The main clues about what might be wrong in this office environment came from the conversation with the office occupants and then subsequent investigation of the ceiling cavity and the ventilation system. The occupants stated that the indoor air quality was worse towards the end of the working day and this issue was reoccurring on a daily bases. This prompted an investigation of the air supply to the offices. It has been found that this office has virtually no fresh air supply even though the office ceiling had 6 air conditioning units installed. The office managers did not realise that the installed units only re-condition the air but do not provide fresh air. Typical air condition unit would heat, cool and filtrate indoor air and re circulate it back into the office space. The measurement of carbon dioxide gas in the office environment showed that the carbon dioxide concentration increased from just below 500ppm to over 2500ppm in the late afternoon. Carbon monoxide at this concentrating does not present a health hazards and it does not cause odours etc but it is a reliable indicator of an insufficient air supply.
Forensic analysis of the collected dust also showed another potential indoor air contaminant which might contribute to adverse symptoms experienced by the occupants. Microscopic analysis of the dust revealed the presence relatively large circular particles. The symmetrical circular shape of all the observed particles suggested that they were formed by liquid aerosol droplets squashed into circular shapes by the microscope cover slide. The most likely origin of these particles was the photocopying machine installed in the corner of the office. The health effect of these droplets could not be ascertained but it is safe to assume that they would at least contribute to the poor air quality.
The overall conclusion of the investigation was that the main culprit in this particular case was the lack of fresh air supply and possible irritation of aerosolised photocopier particles.
By Tomas Gabor