We examined changes in the self-reported prevalence of respiratory symptoms and total serum immunoglobulin E (IgE) among hairdressers after local exhaust ventilation was installed in some hairdresser salons. We also examined differences in these variables between current and former hairdressers. The survey was a prospective study on 91 female hairdressers and a control group of 80 female office workers. Total serum IgE remained high in the hairdresser groups both in 1995 and 1999 (101 vs. 105 IU/mL blood). The IgE levels among office workers were low in 1995 and 1999. Forty percent of the hairdressers in 1995 had left their profession by 1999, 5.7 times the rate among office workers. The frequency of wheezing in the past year decreased significantly among current and former hairdressers. Our data suggest that hairdressers who remained in their profession were a highly selected and healthy group of workers. The improvement in symptoms might be explained by the reduced exposure resulting from the installation of local exhaust ventilation.