Perceptions, subjective symptoms and syndromes related to IAQ and their use in guideline settings

DefinitionsHealth is a state of complete physical, mental and social well-being and not merelythe absence of decease or infirmity (WHO 1948). The effects of interest indoorstherefore include both adverse effects and changes of well-being. Building-RelatedIllness (BRI) is a group of known causalities between symptoms and indoor exposuresto air pollutants. Generally, the causalities have a uniform clinical picture and aspecific cause of the complaints. Many BRIs are low exposure levels manifestationsof adverse effects known from high exposures e.g. occupational exposures. Thesymptomatology is important for diagnoses of adverse effects at low exposure levelsindoors. The prevalence of building-related symptoms (BRI) is commonly used tocharacterize the indoor air quality (IAQ) in office buildings (Niemela et al 2006). Anassociation may exist between BRI and productivity or sick leave (Niemela et al2006).Objective health effects are quantifiable changes or signs observed by an independentobserver (not the exposed). In contrast, symptoms and perceptions are personalexperiences or judgements made by the exposed occupant. Symptoms are unspecifici.e. many exposures may cause each of them. Therefore they do not alone identify theexposure cause. For each symptom multiple response modifiers and multiple biasesare possible and different persons may have different spectrum and intensity ofsymptoms. Also, most indoor exposures may cause a number of different signs andsymptoms. Therefore, objective measurements of effects are preferred and subjectiveratings should be substituted by objective measurements where possible but few areavailable. On the other hand, objective measurements are expensive and timeconsuming, a fact which in many cases prevent their use and in the absence ofinstrumentation for chemical detection of small amounts of some air pollutants, thesenses remain the most sensitive indicator system (Berglund et al 1992). Added to thisis that discomfort is subjective by nature and cannot be measured without subjectiveevaluations. Many symptoms are therefore important per se, and cannot be substitutedby objective measurements.AimsThis presentation is aimed at both an update on the biological background for knownsymptoms and perceptions in IAQ science and practice as well as presenting some ofthe newest literature in the field. In addition recommendations are given on how to usesymptoms and perceptions reports in field investigations and IAQ sciences. Thepaper discusses how substitution of subjective evaluations can be made with objectivemeasurements, and if IAQ guidelines can be defined for signs and subjectivesymptoms. Finally, recommendations are given on guideline settings for IAQ.This review includes literature younger than a review made by Berglund et al (1992).It does not pretend to be complete but merely summarizes uses of symptoms andperceptions during the last 5-7 years in IAQ research and managements of buildings.The focus is on symptoms and subjective ratings, not on objective health effects.