This investigation consisted of an intervention study of asingle officebuilding. In the first study, already reported, itwas concluded thatmicrobiological and chemical factors wereunlikely to be responsible forsymptoms of sick buildingsyndrome (SBS) in this building. The focus of theinvestigationtherefore narrowed down to the physical factors. Theseincludethe thermal aspects, and aspects relating to air quality,lighting and acoustics.
This report contains the results of the second study,carried out after intervention measures had been implemented.The questionnaire usedpreviously was shortened and retested. Ascoring system was used to ratesymptoms and find associationswith SBS. The most prevalent physicalfactors were reports ofdry air, stuffy air and noise, but the factors moststronglyassociated with SBS symptoms were ventilation noise,staticelectricity and dust. The dust appears to be produced bythe supplyventilation system. The intervention measuresprovided the building withimproved thermal control. This hadsome effect on the perceived airquality, but the effect on SBSsymptoms was slight. Although air flows tothe rooms wereadequate, the distribution of supply air in the rooms was stillpoor after intervention.
The acoustic environment was examined because of the strongassociationfound between complaints of ventilation noise andSBS symptoms.Measurements showed that many occupants were beingsubjected to over 70 dBof noise produced by the ventilationsystem. Much of this was in theinfrasound region below 20 Hzand inaudible. The biological effects ofinfrasound have beenreported to include symptoms such as headache,fatigue, nauseaand lack of concentration. The descriptions of these symptomsare very similar to the descriptions of some SBS symptoms.Theresults from this study showed that opening a window couldincrease levelsof infrasound. Reducing fans speeds providedsome noise reduction, althoughthe effects in the infrasoundregion were slight. Closing both windows and doors gave thebiggest reduction, but this adversely affects air qualityandinterferes with working routines.
Other factors considered in this study are allergy,circadian rhythms,electromagnetic fields, individual controland lighting. The strongestassociation with SBS symptoms waswith atopic conditions of asthma,allergy, eczema and allergy.Evening types had more SBS than morning types,which is a newfinding in SBS studies. Working with computers had littleeffecton SBS in this study, and the literature suggests that theeffectsof electromagnetic fields in an office environment areslight. Individualcontrol over the work and the indoorenvironment appears to be associatedwith SBS. High levels oflighting were slightly associated with SBS.
The most effective remedial measures in this building wouldbe to lower the supply air temperatures to give improved airdistribution, to filter theair at the supply terminals toreduce the dust, and to install an activenoise control systemto reduce levels of low frequency noise andinfrasound.
KEYWORDS:Sick building syndrome, allergy, infrasound,air quality.
Stockholm: Energiteknik , 1999. , 155 p.