The purpose of the study was to assess the working conditions in hairdressing salons and the influence of work factors on the workers' health. Twenty randomly sampled hairdressing salons in the Helsinki, Finland, metropolitan area were selected for the study. The study was performed during winter 1994-1995; itincludeda survey of the hairdressing chemicals in use, the measurement of physical and chemicalworking conditions, and a self-administered questionnaire of the work environment and health of the workers. The air temperature varied between 16-25degreesC, air velocity 0.02-0.3 m/s, and relative humidity, 18-42 percent. The total dust concentration varied between 66-133 mu g/m3. The concentration of volatile organic compounds was 84-465 mu g/m3 and the peaks rose to 25-45 mg/m3. The highest concentration of ammonia detected was 3.5 mg/m3. The longterm concentrations of thioglycolates and persulfates were at their lowest below the detection limit, and at their highest 1.8 mu g/m3 for thioglycolates and 4.7 mu g/m3 for persulfates, respectively, and the peaks of persulfates, 30 mu g/m3. Hairdressing chemicals, awkward work postures, and repetitive movements were the most frequent causes of discomfort and for some had caused a work-related disease. Good general ventilation decreased the health complaints caused by hairdressing chemicals, but caused discomfort as a result of drafts. On average, the physical and chemical working conditions in the hairdressing salons were satisfactory compared with the Finnish criterion for indoor climate. However, the frequent high peak concentrations of chemicals during dyeing, bleaching, permanenting, and aerosolspraying stillpose a significant health problem. Although effective general ventilation alleviated the effects of the air pollutants, it could not completely solve the problem. Therefore, localexhaust ventilation is recommended at the mixing places for hairdressing chemicals and wherever they are applied to the hair. According to our results, already increasing the air exchange rate up to 5 to 7 times per hour during the high exposure jobs would improve the situation.