The upper respiratory tract: mucous membrane irritation

Despite the widespread recognition that mucosal irritation is a cardinal feature of "sick-building syndrome," few data exist on the cause, natural history, or pathophysiology of upper respiratory mucous membrane irritation. The baseline prevalence of nasal symptoms among building occupants is often 20%, but in some studies it is as high as 50 to 60%. New techniques of nasal challenge and analysis of cells and mediators in nasal lavage fluid have proved useful in the assessment of rhinitis caused by antigens, cold air, and viruses, and these techniques are now being applied to the study the response to irritants. Human inhalation challenge studies have recently demonstrated a spectrum of sensitivity to environmental tobacco smoke, but the basis for this difference requires additional investigation. Animal and in vitro studies indicate that the chemosensitive neurons and airway epithelium may be critical targets for irritants that participate in the induction of inflammation. New research methods are needed, particularly to evaluate complaints of nasal congestion, drying, and irritation. Techniques should be developed that may be useful for field studies, where the health effects of a complex mixture are being assessed in a specific indoor environment. There exists a group of individuals who report a variety of symptoms on exposure to low levels of common volatile organic mixtures such as perfume, cigarette smoke, and cleaning agents. Some of these individuals report having occupied "sick buildings" during the time their symptoms began. Research is needed to understand the basis of their complaints, their etiology, and treatment.