Intolerance may develop to various everyday environmental exposures at levels that are well below those known to cause adverse health effects. Reactions initiate typically from odorous substances. Reactions range from unpleasant sensations and annoyance to multi-organ symptoms, severe disability, and major restrictions in daily life and work. Symptoms often lead to exposure assessments at work and may result in excessive actions to eliminate minor exposures. In environmental intolerance, occupational health care is the front line actor in primary and secondary prevention, and support of recovery.
Human reactions to indoor air can be explained by building-related, psychosocial and individual factors. The non-specific symptoms without a clear cause have also been called the sick building syndrome. In Finland, the prevalence of building-related intolerance is common and higher than elsewhere in Europe. Also, the 37% of working population perceives indoor air harmful to their health. Indoor air problems, especially moisture-damage and moulds are considered a major health risk in Finland.
The mechanisms of environmental intolerance have become more clear. The recognition of functional symptoms and environmental intolerance from indoor pollutant-related symptoms is not easy, but it is possible. The differential diagnosis of symptoms is necessary, because intervention may be the opposite considering e.g. avoidance.
The development, sustenance and perpetuation of environmental intolerance should be prevented. In less severe cases, psychoeducation at occupational services may be sufficient. In cases with severe indoor air -related idiopathic environmental intolerance, so far, results show resistance to other than avoidance and means reasoned by the toxic-hypotheses. However, the recognition of environmental intolerance as one among other functional disorders will open new promising intervention avenues. Studies on new therapeutic means are under investigation.