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Background: Chemical intolerance (CI) is a term used for individuals experiencing symptoms triggered by odorous and pungent substances such as perfume, cleaning agents, mold smell and tobacco smoke. The prevalence of CI range from 0.5-52% depending on definition, and it is overrepresented among women. Living with CI can cause difficulties in daily life, with work, hobbies, social activities, and reduce quality of life. The International Classification of Functioning, Disability and Health (ICF) is a tool to measure an individual’s life situation related to a health condition, in the areas body functions, body structures, activities and participation, and environmental factors.

Aim: The aim of this thesis was to develop a tool that could be used to help persons with CI. Furthermore, the aim was to better understand and describe disability and health aspects of CI in the context of the biopsychosocial model of ICF.

Method: This thesis is based on the results from four studies with different methods: 1; The questionnaire development study in which a questionnaire instrument based on the ICF, for persons with CI, was developed and evaluated in terms of validity and reliability. 2; The survey study using the newly developed ICF-questionnaire, with 112 respondents. 3; The qualitative study with data collection from twelve women who wrote descriptive texts that were analyzed with qualitative content analysis. 4; The experimental study of health-related responses to the mold-smelling chemical trichloroanisole, comparing a CI-group (n=14) with a control-group (n=18). During exposure, symptom intensity, odor intensity and odor valence were rated, and physiological measures were recorded.

Results: The development of the ICF-based questionnaire resulted in a final version that consisted of 57 items divided in three parts. It showed good content validity, readability and face validity, and all parts showed good internal consistency, Cronbach alpha: 0.73-0.87. Test-retest showed good to very good (≥0.61) Kappa agreement for 37 items, moderate (0.41-0.60) for 17 items, and poor or fair (<0.41) for 3 items. Regarding the ICF areas activities and participation and environmental factors, the results from the survey study showed high ratings on difficulties in activities and participation, and environmental barriers. Six themes were identified in the qualitative study: Being limited in participating in society, being forced to behave incompatibly with one´s personality, experiencing lack of understanding and respect from others, experiencing insecurity, being dependent on others, and being forced to choose between the plague and cholera. Regarding the ICF area body functions, the survey study showed reports of several different symptoms and affective and behavioral reactions in response to odorous and pungent substances. The mean of severity of symptoms, was high, 79 on a scale from 1-100. The severity of symptoms was found to have the strongest association with degree of difficulty in activities and participation. The results of the experimental study did not show more health effects of the trichloranisole exposure in the CI-group than the control-group. However, the results showed a high inter-individual variation in ratings of odor intensity, odor valence and symptom intensity.

Conclusions: The ICF-based questionnaire is valid and reliable and can be used as a tool to measure difficulties in activities and participation, and impact of environmental factors. Individuals with relatively severe CI have major difficulties in activities and participation in the society. They also experience large barriers in society, both in form of triggers and in form of negative attitudes from others. The body functions in CI is affected in the form of a large variety of symptoms, as well as affective and behavioral reactions in response to odorous and pungent substances. TriCA does not seem to affect body functions for persons with CI in general, but for some individuals it can affect body functions. Both coping strategies exposing to and avoiding odorous and pungent substances can lead to increased difficulties with activities and participation. The severity of symptoms plays the most important role for the degree of difficulty in activities and participation.