Abstract
The measurement of volatile organic compounds (VOCs) and aldehydes in indoor air in a newly built wooden house showed that the concentrations of acetaldehyde, hexanal, nonanal, acetic acid, acetone, terpenes and p-dichlorobenzene were higher than those of other VOCs such as toluene and formaldehyde. An investigation of the emission sources of these compounds revealed that the under flooring space was a common source for all compounds except p-dichlorobenzene. An analysis of the flooring adhesive polymer revealed that water-based polyvinyl acetate (PVA) adhesive had been used during floor construction; therefore, the compounds emitted from a cured PVA adhesive prepared in a laboratory and their degrees of variation with humidity were investigated. It was determined that the cured PVA adhesive predominantly emitted acetic acid, acetaldehyde, acetone and vinyl acetate, and the emission levels increased with humidity. Because the under flooring space has poor ventilation, the emitted compounds from the cured PVA adhesive were collected in a sampling bag made from polyvinyl fluoride film and the concentration change in the compounds was monitored for 7 days. The measurement results on the seventh day showed that the concentrations of both acetaldehyde and acetone were 2.5 times those at the start of the measurement. Considering that coniferous material emits acetaldehyde, acetone, terpenes, hexanal and nonanal, the compounds detected in higher concentrations in the newly built house were believed to be emitted mostly from the PVA adhesive and wood-related construction materials. It was considered that the emitted compounds first stagnated in the under flooring space before gradually leaking into the indoor area through the narrow gaps between the floor materials.
