Due to economic growth, human beings have been coming in greater contact with various chemicals. Thus, the people who have become the chemical sensitive are also increasing, which results in anaphylaxis for various chemicals. Recently, a sick house syndrome is occurring frequently in an indoor environment. Especially, since the aged and infants who are physically weak, pass their time mainly in a room, there is a high risk for them to fall into the syndrome, of which the results are asthma or allergy. In this study, the ability of houseplant (Golden pothos) to remove the chemicals was examined. An indication of the ability, purification rate P_a of the plants, was examined in an experimental sealed chamber. P_a was derived from the measurements by tin oxide gas-sensor characteristics for a chemical. To calculate P_a, the peak of the sensor output was divided by the full-width at half maximum. The following chemicals were examined; formaldehyde, toluene, xylene, benzene and trichloroethylene. The rate became high when the plant was illuminated. The smaller the molecular weight of a pollutant was, the larger the purification rate became. Namely, it took a long time to remedy an indoor environment when chemicals with large molecularweight were adopted in the architecture-materials. Gaseous chemicals diffuse directly into soil. Features of the sensor characteristics in the soil were similar to the characteristics in the chamber atmosphere. Low purification ability of potted soil without plants was found. In this study, it was demonstrated that the plant tested had a higher ability to absorb ammonia than formaldehyde.

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The droplet method is unique sampling procedure utilizing a droplet which containing a reagent solution, which made at the end of the stainless-steel pipe. This method is able to sampling various soluble substances, which needs suitable trapping reagent. Most of the interfering ions and species did not interfere in the determination. We investigated to obtain the best condition to the droplet method; reagent delivery rate, the size of the end of the pipe, effects of wind velocity and humidity were examined in the wind-tunnel method and nitrogen dioxide (NO₂) was used as a test gas. Reagent solution was distilled water contained 3% triethanolamine. Satisfactory result was obtained and the detection limit for NO₂ is 5 ppb (C. V: 5-20%). The results were satisfactory when compared with a reference method. This droplet method was applicable to the measurement of NO₂ in air samples.

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The effects of ozone (0₃) and soil water stress, singly and in combination, on leaf gas exchange rates, leaf ultrastructural characteristics and annual ring width of Fagus crenata. seedlings were investigated. Three-year-old seedlings were exposed to charcoal-filtered air (<5nmol·Emol^-10₃) or 60 nmol·mol^-10₃, 7 hours per day (11:00-18:00), for 156 days from 10 May to 12 October 1999 in naturally-lit growth chambers at 20/15°C (day/night). During the same period, half of the seedlings in each gas treatment received 250 mL of water at the 3-day-intervals (well-watered treatment), while the rest received 175 mL of water at the same intervals (water-stressed treatment). The long-term and mild soil water stress induced significant reductions in leaf water potential after July, and then the net photosynthetic rate at 350 μmol·Emol^-1CO₂ (A₃₅₀) stomatal diffusive conductance to water vapor and transpiration rate were significantly reduced after August. In addition, the diameter of plastoglobuli in the chloroplasts was significantly increased by the soil water stress. The 0₃ caused significant reductions in A₃₅₀, maximum net photosynthetic rate at saturated CO₂-concentration (A_max), carboxylation efficiency of photosynthesis (CE) and darkadapted maximum chlorophyll fluorescence (F_v/F_m). The 0₃-induced reduction in the net photosynthetic rate was firstly due to the reduction in the quantity and/or activity of RuBP carboxylase/oxygenase (Rubisco), and then due to the reductions in the regeneration rate of RuBP and activity of photochemical system in the chloroplasts. Furthermore, the size of starch grain in the chloroplasts and annual ring width were significantly reduced, whereas the diameter of plastoglobuli was significantly increased by 0₃. No significant interactions between 0₃ and soil water stress were observed with the leaf gas exchange rates, leaf water potential, ultrastructural characteristics of leaf mesophyll tissue and annual ring width throughout the one-growing period. Based on the results of the present study, we concluded that the photosynthesis and structural characteristics of Fagus crenata are affected by ambient levels of 0₃ and long-term mild water stress, and these two stresses are related to the decline of this tree in Japanese mountainous areas such as Tanzawa Mountains in Kanagawa Prefecture.

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At Nippon Telegraph and Telephone Corporation, environmental investigation of machine rooms was carried out using a handy and cheap metal plate exposure method from the viewpoint of preventive maintenance on communication equipment.
It was proven that this method is effective for evaluating indoor environments. However, when the exposure period of the metal plate is shortened, the business trip for the installation of the metal plate increases, and the low cost advantage is lost.
We examined a handy and cheap method which was able to evaluate atmospheric environment during a short-term exposure.
The main results are shown as follows.
(1) We found the condition of non-sealing up structure to maintain corrosion amount information on a metal plate for long term.
(2) We created a device that continuously records the amount of corrosion using a non-sealing up structure. We named “Environmental corrosion recorder”. Six pairs of metal plates are installed in the recorder. By using this recorder, the business trip operation of conventional method is decreased to 1/4 or less.
(3) We carried out experiments on this recording method and the conventional metal plate exposure method concurrently over four months in six places. It was proven that the data taken from the recorder was almost the same as that taken using the conventional method.
(4) The correlation coefficients for the amount of the sulfur corrosion detected by the two evaluation methods were 0.96, 0.96 and 0.76 in the machine room, the office and outdoor, respectively. The correlation coefficients for the amount of the chlorine corrosion detected by the two evaluation methods were 0.93, 0.97 and 0.96 in the machine room, the office and outdoor, respectively.

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