Objective: 2-Ethyl-1-hexanol (2E1H) is a volatile organic compound (VOC) which seldom attracts attention in Japan. This study aimed at clarifying changes in its concentration over time, emission sources, and students' symptoms in classrooms of a university building where indoor air was found to be markedly polluted with 2E1H.
Methods: From March 2001 through September 2002, we measured VOC concentrations in Building A, constructed in 1998, as well as Building B (Sept. 2002), constructed over 30 years ago and considered as a control. Airborne concentrations of 13 carbonyl compounds were quantified with diffusive samplers and high-performance liquid chromatography, and those of 41 other VOCs with an active sampling method using charcoal tubes and a gas chromatograph with a mass spectrometer (GC-MS). In August 2002, we also measured VOC emissions from the floors using double-cylinder chambers and the airborne concentrations of phthalate esters by filtration sampling, both by GC-MS. Subjective symptoms in 315 student classroom users in Building A and 275 in Building B were surveyed in July 2002 with anonymous self-administered questionnaires.
Results: 2E1H concentrations in Building A, which exceeded the Japanese recommended threshold of total VOCs (400 microg/m3) in some measurements, tended to be lower in winter and higher in summer, and did not show any tendency for decrease over time. No association was found between indoor concentrations of phthalate esters and those of 2E1H. The concentrations clearly differed between rooms, related to emission rates from the floors. Carpeting materials had been placed directly on the concrete floors in rooms with higher emission levels, whereas the carpeting materials and the concrete floor did not make contact in the room where emission was lower. The odds ratio for subjective symptoms with students in classrooms in Building A was not higher than in Building B where the 2E1H concentrations were low. However, a few students limited to Building A did complain of problems with the nasal passages, throat and lower airways.
Conclusion: Compounds containing 2-ethyl-1-hexyl moiety are presumably hydrolyzed to emit 2E1H when the backing of carpeting material is in contact with concrete floors. Although no significant difference was observed in symptoms between the student groups in the two buildings, this was possibly due to the small sample size. Measures to prevent 2E1H emission and dose-response relationships in sensitive individuals should be studied further.