Abstract
The concentrations of indoor air phthalates (10 compounds) were measured. The samples were collected from 92 rooms of 46 houses and 50 offices of 25 buildings in Tokyo during the summer and winter months between December 1999 and October 2000. Air sampling was carried out using a quartz fiber filter and a solid phase extraction disc (EmpoerTM C18) to collect the particle and gas phase compounds, respectively. The air was pumped through the filters and discs at a rate of 10L/min for 24 hours (14.4m3). They were extracted separately with acetone and phthalates were analyzed by GC-MS.
The compounds predominantly detected in indoor air were di-n-butyl phthalate (DnBP) and di-2-ethylhexyl phthalate (DEHP). The ranges of concentrations of these two phthalates were 78.4-7, 220 ng/m3 and 10.8-2, 380 ng/m3, respectively. The six compounds detected in almost all indoor air samples were dimethyl phthalate (DMP), diethyl phthalate (DEP), diisobutyl phthalate (DiBP), DnBP, benzyl butyl phthalate (BBP) and DEHP. The median concentration ratio of indoor to outdoor air concentrations of these 6 compounds varied from 2.1 to 45.6. A comparison concentrations in houses and offices showed that the median of 5 of the 6 compounds (the exception being DEHP) was higher in offices than in houses. However, the maximum of 5 of the 6 compounds (the exception being BBP) was higher in houses. The concentration levels of some phthalates, including DnBP and DEHP, were significantly positively correlated with room temperature in the houses and offices studied. At a room temperature range of 4.9-31.2°C, more than 91.3% of dimethyl phthalate and less than 11.0% of DEHP was in the gas phase.However, the concentration of DnBP in the gas phase increased with increasing room temperature. Below 20°C, only 6.5% of DnBP was in the gas phase, compared to 89.8% in the gas phase above 30°C.
