I have been invited to carry out an extensive air quality investigation in a IT suite and a large office complex. The IT room was affected by large moth infestation. In order to resolve the infestation issue a contractor company has been appointed to carry out a fumigation of the room. The room has been fumigated by an approved fumigation agent containing Bendiocarb as a principal constituent. Following the office fumigation one member of the staff has developed sudden and severe allergic reaction which manifested itself as skin reddening and rashes. Several other members of staff have also developed milder reactions. Since the incident the rooms has been intensively ventilated and as a result the symptoms have gradually subsided. At the time of the assessment only the person who experienced initially the strongest reaction was still experienced allergic sensitisation when visiting the IT room.
The IT office was located on the ground floor of the building and consists of one open plan room approximately 9 metres long, 7 metres wide and 2.4 meters high. The rooms had suspended mineral fibre ceiling tiles, plasterboard walls and carpeted floor. Another affected room was the IT store room located in the basement of the building accessible from the outside. The room was approximately 1.2 meters wide, 1.2 meters long and 2.4 meters high. The IT store is not occupied for extended periods of time.
I have carried out extensive chemical and biological sampling in order to confirm that the fumigation agent was indeed responsible for the symptoms experienced by the office staff. I have carried out sampling for volatile organic compounds which were detected in the IT Office at total concentration of 3297 µg/m3. VOC’s were detected in the IT Store at a total concentration of 83 µg/m3.
Bendiocarb as principal component of the used fumigation agent was not detected in the indoor air or as a surface contaminant of the IT office furnishings. The detection limit of the elected method was 7ug/m3 and the World Health Organisation has set and exposure limit to 200 ug/m3.
From the various volatile organic compounds Propan 2-ol (isopropyl alcohol) was detected at a concentration of 2900 µg/m3. Dipropyle glycol was detected at a concentration of 65 µg/m3. 1-methoxy -2-propanol was detected at a concentration of 14 µg/m3. Toluene was detected at a concentration of 16 µg/m3. Hexanal was detected at a concentration of 13 µg/m3. Xylene was detected at a concentration of 6.5 µg/m3.
1-butoxy-2-propanol was detected at a concentration of 9 µg/m3. Dipropylene glycol methyl ether was detected at a concentration of 83 µg/m3. 1-(2-methoxypropoxy) propanol was detected at a concentration of 94 µg/m3. Aldehydes were detected in the IT Room at a concentration of 60 µg/m3 of which formaldehyde formed 34 µg/m3. Isovaleraldehyde was detected at a concentration of 4 µg/m3.
The concentration of mould spores in the IT room was significantly lower than the in comparison to the external background sample. The concentration of airborne bacteria in the IT room was significantly lower in comparison to the external background sample.
I have concluded that the detected total volatile organic compounds were present at the concentration significantly exceeding the recommended indoor air quality values. A propan-2-ol (isopropyl alcohol) was the single most concentrated chemical compounds. The likely source of this chemical compound is electronic or screen cleaning solutions. All other chemical compounds were detected at significantly lower concentrations and can mostly be associated with cleaning products, degreasers and coatings. Propan-2-ol is a significant contributor to poor indoor air quality. However it is unlikely that propan-2-ol (isopropyl alcohol) present as a vapour in the working environment could result in the symptoms experienced by some of the room’s occupants.
I have also concluded that the suspected Bendiocarb a principal constituent of the fumigation agent was not detected in the air or on surfaces of the IT room. However is needs to be noted that Bendiocarb is a biodegradable chemical compounds with a reported decomposition half-life between 2-6 weeks (soil). At the time of the assessment the concentration of this fumigation agent was likely to be extremely low. In the industry Bendiocarb poisoning has occurred in situation where this product was applied at very high concentration. No dermal irritation is reported for Bendiocarb. I have recommended to maintain high ventilation rate in the IT office during working hours due to the likely use of variety of chemicals mainly associated with cleaning of electrical components.
In terms of microbiological contamination I have concluded that indoor concentration of airborne moulds and bacteria in the air was lower than the comparative background sample. The indoor air quality with respect to mould spores and bacterial contamination can be described as good. No sources of likely mould or bacterial contamination were identified in the office. The symptoms experienced by the office staff were unlikely to be caused by exposure to airborne moulds or bacteria.
It was my opinion that the most likely reason for adverse health symptoms experienced by some of the employees working in the IT Room was initial sensitisation by elevated concentration of chemicals post fumigation. Slowly diminishing pattern of exposure symptoms in the office occupants suggested that an unspecified chemical agent or a combination of chemical agents was likely responsible for adverse health symptoms. Likely continuous exposure to elevated concentration of chemicals in the office has most likely contributed to increased chemical sensitivity of some of the employees.
By Tomas Gabor