Sick house syndrome and multiple chemical sensitivity syndrome caused by indoor chemical substances have become a problem. In addition, energy-saving measures to control the outside air intake rate according to indoor carbon dioxide concentration and the number of occupants have received attention in recent years. However, attention is rarely paid to the increase in indoor chemical concentration due to the decrease in the outside air intake rate. To measure the concentrations of indoor chemical substances, such as formaldehyde and volatile organic compounds (VOC), gas chromatography, high-performance liquid chromatography and other techniques need to be used and it is not easy to obtain measurements in a short time. Further, there are no systems capable of accurately monitoring the concentration of indoor chemical substances. To solve these problems, a simplified method of measuring the concentration of total volatile organic compounds (TVOC) using a semiconductor-based sensor was developed and the development results were presented in the previous report. This paper reports the evaluation results of the characteristics of three types of semiconductor-based sensors installed in two buildings, the results of confirmation that the semiconductor-based sensors could be used for monitoring the concentration of chemical substances in the buildings, and the subjects for future study.

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Fungi pollution was periodically investigated from February 2007 to September 2009 (five times in total) in an art museum in Shizuoka Prefecture. In this case, by observation of a colony, or observation by optical microscope, some difficult fungi (Aspergillus section Restrictus) to identify were isolated from the surface of the work collected, and from the air in a storehouse. It was thought that these fungi isolated caused contamination and degradation of the art work, and identification by a gene analysis was performed on about ten isolates. The gene analysis was conducted by determining the base sequence of the D1D2 region of the 26SrRNA gene. From the result of identification, the isolates were cultivated using several sorts of culture media for fungi, and comparison of the shape of the colony and comparison of microindentations such as the conidial head with a light microscope were conducted. As a result, the samples were classified into about five strains. One of species was Aspergillus penicillioides known as a cause of the brown spot (foxing) on art work of paper or books. It was suggested that the other strains were related species of A. penicillioides, and a high possibility that it was the offending fungi foxing of the art work of paper and staining of paintings.

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α-Pinene is a major compound contributing to indoor air pollution in Japanese residences together with many aliphatic or aromatic hydrocarbons. In the present study, the amounts of each enantiomer of α-pinene ((+)- and (−)-α-pinene) absorbed by a resident in a Japanese home were estimated by evaluating their inhalation toxicokinetics in rats. Measured amounts of the substances were injected into a closed chamber system in which a rat had been placed, and the concentration changes in the chamber were examined. The toxicokinetics of the substances were evaluated based on concentration-time courses using a nonlinear compartment model. The absorption amounts per unit time in rats exposed to the substances at constant concentration were simulated using the estimated values of the toxicokinetic parameters. The estimated amounts for the two enantiomers showed approximate agreement. When the values were compared with those for aliphatic or aromatic hydrocarbons examined in our previous studies, α-pinene was estimated to be absorbed more easily by inhalation than n-hexane, n-heptane, n-nonane, n-decane, toluene, xylenes, ethylbenzene and styrene, and to be absorbed about the same level as 1,2,4-trimethylbenzene. Their absorption amounts in human residents were extrapolated from the results for rats and the residential concentrations found in our previous study. The total amount of the two enantiomers absorbed was estimated to be 31 μg/60 kg of human body-weight while at home for 16 h (residential concentration: 4.4 μg/m³ as median value). The value was the highest after that for toluene. Similarly, in a residence where air pollution was marked, the absorption amount of α-pinene (13 mg for 16 h in a residence with an indoor maximum concentration of 1.8 mg/m³) was estimated to be much more than those of other substances. The value (13 mg) was the same level as the tolerable daily intake (TDI) calculated from the No Observed Adverse Effect Level (NOAEL) proposed by the Environmental Protection Agency (EPA).

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The emission flux of styrene monomer from expanded polystyrene beads (EPSB), expanded polystyrene (EPS) and others, such as pillow, cushion and soft toy samples was measured by using passive flux sampler (PFS). The styrene emission flux was measured at 298 K (11-220 μg/m²/h), 309 K (32-620 μg/m²/h), and 323 K (203-2.23×10³ μg/m²/h) and it was found that the emission flux increased with increase in temperature. Apparent activation energy for styrene emission flux from samples was measured < 100 kJ/mol. Activation energy for thermal degradation reaction of polystyrene chain was reported 210 kJ/mol. Thus, it is observed that the rate controlling step is not degradation reaction step but may be mass transfer steps. It may face some difficulties for the users of expanded polystyrene-used products as if expose styrene and other chemical compounds.

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We have developed a portable device for formaldehyde monitoring, and have carried out indoor air monitoring in several houses. The absorbance difference of the developed sensor element was measured at regular intervals in the monitoring device and converted into the formaldehyde concentration. This was possible because the rutidine derivative that was formed as a yellow product of the reaction between β-diketone and formaldehyde was stable in the sensor element. The device contained an LED as a light source and photodiodes as photo-detectors. It was sufficiently small (10 cm × 10 cm × 4 cm) to be installed at a desired location in the house. In addition, the device was able to monitor a closed area without a convection flow, because it did not use a pump for air sampling. The detection limit was 5 ppb x hour, and we estimated it took about 1 hour to detect a formaldehyde concentration of 94%.
The developed sensor device was small and easy to use and we successfully carried out hourly formaldehyde monitoring using our monitoring device under several indoor conditions. We found that a high formaldehyde concentration could be measured in a room containing furniture and clothes. We also found that, although the formaldehyde concentration decreased rapidly when ventilation was provided, it recovered rapidly in several hours when we stopped ventilating the room.

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A precise measurement method for 3-ethenylpyridine (3-EP) and nicotine by using an alkaline-coated cartridge was developed. The amounts of 3-EP and nicotine recovered from the spiked cartridge were more than 80% during air-sampling time of 12 hr. The detection limits of 3-EP and nicotine by this method for an air volume of 72 L were 0.08 μg/m³ and 0.10 μg/m³, respectively. In a smoking room, the concentration of 3-EP was found to be 0.85-5.4 μg/m³, and that of nicotine, 6.0-34.1 μg/m³; moreover, the 3-EP/nicotine ratio was found to be 0.14±0.03. In the smoking room, the concentration of 3-EP was significantly correlated with that of nicotine (correlation coefficient, 0.94). Side-stream smoke was collected in a Tedlar^® Bag, and changes in the concentrations of 3-EP and nicotine during 4 hours were monitored. The 3-EP/nicotine ratio in the side-stream smoke increased with progress in time; at the start of the measurement, this ratio was 0.13, and 4 hours later, it was 1.02. The Tedlar^® Bag film was cut, and the concentration of 3-EP and nicotine on the film surface as well as in the air contained in the bag were measured; nicotine was found to be more adherent than 3-EP. Therefore, it was considered that increase in the 3-EP/nicotine ratio with progress in time was caused by a rapid decrease in nicotine concentration in the air that was attributable to easy adherence of nicotine to the film surface.

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