The concentrations of volatile organic compounds (VOCs) and carbonyl compounds were measured at 40 residences in 3 cities in China (30 in Chengdu and 5 each in Beijing and Changsha). Indoor, outdoor, and personal exposure samples were simultaneously collected at each site. The average concentrations of benzene, toluene, xylene, and formaldehyde, particularly those of benzene and formaldehyde, were significantly higher than those in other countries, both indoors and outdoors. A significant correlation was observed between the indoor concentration of, and personal exposure to VOCs and carbonyl compounds. Indoor/outdoor ratios of many VOCs and carbonyl compounds exceeded 1, indicating the presence of emission sources in the indoor environment. The relationship between indoor air concentrations or personal exposure to VOCs and carbonyl compounds and time elapsed after interior decorating, type of interior decoration, ventilation time, average length of furniture usage, number of pieces of furniture per floor area, interior decorating materials of floors, interior decorating materials of walls, and smoking were studied. It showed that VOCs and carbonyl compounds in Chinese indoor environments were influenced by factors such as time elapsed after interior decorating, type of interior decoration, decorating materials, and average length of furniture usage. The lifetime cancer risk of exposure to benzene or formaldehyde is about 10^-4 for each substance. More attention should be paid to the high risk of exposure to VOCs and carbonyl compounds in China.

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A new device (Passive Emission Colorimetric Sensor: PECS) has been developed to easily and precisely measure the emission rates of formaldehyde from various surfaces in residential houses. PECS is a very small device (external diameter: 23mm, thickness: 3.2mm). PECS consists of a polyethylene terephthalate (PET) body and a test paper, which turns red by enzyme reaction in the presence of formaldehyde. At the beginning of measurement, 1 drop of pure water is put into the PECS, the PECS is placed on each of the indoor materials, and 30 minutes later the coloration can be measured by visual observation or absorption photometry.
The response to the color change of PECS in the measurement of reflectance was correlated with the concentration of the solution between 0.4 and 20μg/mL (R²>0.99). In measuring the emission rates from plywood with any order of emission rates using PECS and the desiccator method, both results were nonlinearly correlated (blue LED: y = 0.225x^0.444,R² = 0.995, green LED: y = 0.233x^0.529, R² = 0.992). The precision (N = 7) of the measurement was 4.3% ~ 13 %. The lower limit of quantification (LOQ) of the emission rates measured by PECS were equivalent to 0.06 mg/L measured by the desiccator method. This LOQ is much lower than the emission rates of normal plywood in class F ****(<0.3mg/L).

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Indoor air pollution by chemicals was examined in 105 residences, for which final construction (including renovations) had been completed at least half a year earlier, in Osaka from June 2003 to January 2004. The airborne compounds were collected for 24 hours under normal living conditions. Collected nitrogen dioxide and formaldehyde were measured using the colorimetric method while 38 volatile organic compounds (VOC) and 39 semivolatile organic compounds (SVOC) were analyzed using gas chromatography/mass spectrometry. The median concentrations of nitrogen dioxide (35μg/m³), formaldehyde (31μg/m³), toluene (22μg/m³), and ethylacetate (12μg/m³) were relatively high among the compounds studied, and high concentrations of α -pinene (maximum: 1800μg/m³) and p-dichlorobenzene (1770μg/m³) were found in several residences. The concentrations of p-dichlorobenzene alone exceeded the indoor guideline values of Japan in 10% of the examined residences. The indoor concentrations of formaldehyde and nitrogen dioxide were significantly higher in winter than in summer. The indoor concentrations of di-n-butylphthalate and di (2-ethylhexyl) phthalate were high among SVOCs, and the concentrations of many phthalates and phosphates were significantly higher in summer than in winter. S-421, a synergist, was found in indoor air of a high 90% of the residences. Thirteenfungicides and insecticides containing metoxadiazone, which was not known as an indoor air pollutant, were found in the residential air samples.

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A schoolgirl developed symptoms associated with sick building syndrome during a period of attendance at an elementary school soon after the renovation of the school in February 2002. The quality of the indoor air appeared to be the main cause of her illness, since she recovered after changing schools. The objectives of this study were to clarify the characteristics of the changes in the airborne concentrations of formaldehyde and volatile organic compounds (VOCs) over time, and to present recommendations regarding the renovation of schoolrooms.
Beginning in March 2002 and continuing on a bimonthly basis for two years, we measured in the schoolroom the airborne concentrations of formaldehyde and seven of the eleven VOCs (i. e., toluene, ethylbenzene, xylene, styrene, p - dichlorobenzene, tetradecane, and di- n - butyl phthalate) regulated by the Japanese Health, Labour and Welfare Ministry. The two-yea r results obtained in this study revealed that the airborne concentrations of formaldehyde and the components of the VOCs fluctuated in three different ways depending on their physicochemical characteristics: (1) The airborne concentrations of toluene, ethylbenzene, xylene, and styrene reached peak levels in the summer of 2002, but had decreased dramatically by the summer of 2003; (2) The concentration of p - dichlorobenzene reached a peak level in the summer of 2003; and (3) The concentrations of formaldehyde, tetradecane, and di - n - butyl phthalate reached peak levels in the summers of both 2002 and 2003. These results suggest that the toluene, ethylbenzene, xylene, and styrene that are contained within paints rapidly volatilized during the first summer, and that the formaldehyde and di- n - butyl phthalate that are contained within the furniture or interior materials continue to volatilize at low levels every hot and wet summer. The concentrations of total VOCs and formaldehyde measured in the summer of 2002 had, however, decreased to 54% and 55%, respectively, by the summer of 2003. Based on these observations, we recommend that the renovation of schoolrooms should be completed early during holidays, and that VOCs should be allowed to volatilize, at least in part, during hot summer holidays.

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