There are several methods for determining personal exposure to PM_2.5. Among these methods, the gravimetric method that include collection of PM_2.5 on the filter and measurement of the filter weight have the advantage of measuring weight of PM_2.5 directly. We have developed a low-noise personal pump for collecting PM_2.5, and found that this can be used even in the bedroom. Teflon coated glass fiber filters (T60A20, Pall Corp.) was used for collecting PM_2.5. These filter was heated at 300°c for 6 hours prior to use, and put into a desiccator where relative humidity was kept at 50%. When the filter was PM_2.5 weight can be measured accurately. This method can be applied to not only the personal exposure surveies of PM_2.5 but also indoor/outdoor ones.

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An attempt was made to evaluate the stability of generation on formaldehyde gas at a level typical of an indoor environment by a permeation tube method using paraformaldehyde. The permeation tube was prepared by filling a cylindrical polyethylene tube with paraformaldehyde. The permeation rate (Pr) of formaldehyde gas from the tube was evaluated at 50°c by measuring both the weight loss of the whole tube, which is a normal way to derive a standard permeation rate of a permeation tube, and the amount of formaldehyde at the outlet of a gas generator. The results showed that Pr obtained by formaldehyde gas analysis (Pr_f) successfully became constant after 40 days when the tube was placed in the gas generator at 50°c, and kept stable for more than a year. Meanwhile, at the beginning of the gas generation, the rate of weight loss of the tube (Pr_w) was about 10 times greater than the Pr_f and decreased continuously to meet the Pr_f with 60.0 ng/min for about 210 days. These results indicate that impurities contained in paraformaldehyde are also generated from the tube and caused the excess rate obtained by the previous weight loss method.

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In recent years, many control products against odor pollutants in the toilet are commercially made available in large number, and it requires new technique of reproducing the odor pollutants in the toilet in order to pursue the performance of these control products. The human excreta being the source of micro heat, the odor pollutants rise and diffuse from the excreta through toilet bowls. In such case, the odor pollutants leak from between the thighs and buttocks and contaminate the toilet space. Therefore, it has been one of the issues to find out how to reproduce the indoor air pollution caused by the odor pollutants that leak from toilet bowls. Thus, in this study, we attempted to make new proposal as well as verification regarding the manner in which the odor pollutants are generated from toilet bowls. Specifically, we have 1) developed the "mock body waste" which has the characteristics of the odor generated from the excreta during excretion, and then 2) produced the "stationary odor gas generator" which is capable of the stationary generation and, finally, 3) produced the "odor source sticker" that reproduces the generation of the odor pollutants during non-excretion. The results of our experimental verification were as follows: 1) the mock body waste made of sponge and clay materials was capable of reproducing the characteristics of the ammonia gas that is generated during excretion. It is also noted that, when the mock body waste was placed and the "Odor substance emission area regulator" was mounted, the contaminant concentration values of the substances appeared somewhat lower while the trend of the values concurred with the actual toilet pollution. This technique can be applied to the performance test of the control products such as deodorizing toilet seat and deodorant; 2) the stationary odor gas generator was able to retain the ammonia concentration for a long period of time and proved suitable for the method of testing the products such as deodorizing toilet seat; 3) As the problem during non-excretion is the pollution arising from the deposits on the toilet seat, this pollution may possibly be reproduced by using the "odor source sticker".

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Removal of gaseous volatile organic compounds (VOCs) in indoor air by the photo Fenton reaction using a gas-liquid two-phase photoreactor was investigated. In proposed air cleaning process, the removal of VOCs in the gas phase involves mass transfer with simultaneous chemical decomposition. As the first step of the process, the mass transfer of VOCs from the gas phase to the liquid phase occurs in the gas-liquid two-phase photoreactor. This is followed by the oxidative reaction due to highly-reactive hydroxyl radicals generated by the photo Fenton reaction. The decrease in dissolved VOCs concentration by the photo Fenton reaction leads to enhance the mass transfer. In this study, acetaldehyde as a model hydrophilic VOCs and toluene as a hydrophobic VOCs were used. It was found from the results of one-pass tests that 97% of gaseous acetaldehyde and 50% of gaseous toluene could be removed at the inlet acetaldehyde concentration of 1000ppb_v and the inlet toluene concentration of 1000ppb_v, respectively. In the proposed air cleaning process, because VOCs oxidations occur in the liquid phase, potential harmful incomplete oxidative degradation products could not be detected by PTR-MS.

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