To the Editor.
—Dr Engel1 is to be commended for considering an environmental exposure in his differential diagnosis of a patient with recurrent afebrile flulike symptoms, but I disagree with his description of the sick building syndrome as an example of a "severe allergic reaction" likely to require restriction from work.Sick building syndrome is characterized by symptoms such as mucosal irritation, headache, and difficulty concentrating and often affects a large proportion of occupants of a new or remodeled, mechanically ventilated building. There appears to be no single cause. Factors such as bioaerosols, volatile organic compounds, poor lighting and temperature control, and work stress are likely contributors, although individuals have differing sensitivities to the same conditions. However, as stated in the reference that Engel cites, "there is little evidence that allergy is responsible for most of the features."2 Although these symptoms can be troubling, many investigators feel that