Despite the successively strengthened automotive emission standards and to use more number of low emission vehicles such as methanol or electric vehicles, the NO₂ pollution due to automotive emissions is not improved yet.
In June 1992, “the Law Concerning Special Measures for the Total Emission Reduction of Nutrogen Oxides from Automobiles” was promulgated. Heavily polluted areas including Tokyo, Osaka and Kanagawa, where the daily average NO₂ concentration is presently in excess of 0.06 ppm, were obliged to meet the new requirement for emission from trucks and buses.
Until 2000, by the countermeasure taken in this law, about 30% of total NO_x emission will be cut compared to 1992 volume. In result, about 90% of monitoring station will meet the environment quality standard of NO₂.
In this way, it is estimated that the concentration of the NO₂ will be reduced gradually, but still there would be areas that cannot meet the environmental standards. We have to bring about new countermeasuresuch as restrintion of the use of diesel type automobiles, development of new technology, construction of low emission city.

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The importance for the monitoring of polychlorinated dibenzo-p-dioxins and dibenzofurans (dioxins) in flue gases from various incinerators is now increasing. Several indicators of dioxins such as carbon monoxide and total hydrocarbons have been proposed. In this study, a thermal desorption method is developed to determine chlorobenzenes as an alternative indicator of dioxins because of its simplicity and rapidity comparing with a conventional solvent extraction method.
The flue gas is passed through a set of two adsorbent tubes packed with 0.2g TENAX^® TA connected in series after removing of particulates and dehydration process. These tubes are sufficient to adsorb the chlorobenzenes in flue gas of less than 20l. After sampling, adsorbed substances are desorbed by heating up to 250°C, and simultaneously re-concentrated on a capillary trap being cooled down to-130°C with liquefied nitrogen, then introduced into GS/MS by rapid heating.
The correlation coefficient between the values of chlorobenzenes determined by the proposed method and those of dioxins is 0.9. The fact suggests that chlorobenzenes concentration is an alternative indicator of dioxins.
The sum of the gaseous chlorobenzenes concentration in typical flue gas under the state of an excessive oxygen combustion is about 10 μg/m³N, and dichlorobenzenes and trichlorobenzenes concentrations are relatively high. Although hexachlorobenzene is a trace constituent, it gives a significant effect to the human being due to its toxicity.

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The effects of simulated acid rain alone, or in combination with O₃ on the dry weight growth of Japanese cedar seedlings (Cryptomeria japonica D. Don) were investigated. Two-year-old seedlings were exposed to simulated acid rain at pH 2.5, 3.5, 4.5 or 7.0 (120 ml/pot/day, 2 days/week) with two or three levels of O₃ (charcoal filtered air containing O₃ at 0.1 ppm, 0.2 ppm or 0.3 ppm, 4 hours/day, 3 days/week) for 12 weeks in open-top chambers.
There were no harmful effects of simulated acid rain and/or O₃ on the dry weight growth of the seedlings. The seedlings treated with simulated acid rain at pH 2.5, or with 0.3 ppm O₃ showed the increase in the partitioning of assimilates to foliage and the decrease in that to root during the experimental period. The chlorophyll content of foliage in the seedlings exposed to 0.3 ppm O₃ reduced, and its color changed from green to yellowish green.
The results of these experiments suggest that high acidity of rain or high concentrations of O₃ may induce changes in the partitioning of assimilates to plant organs and the reduction of chlorophyll content of foliage in Japanese cedar seedlings.

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In order to simulate crushing asbestos boar ds in demolition, a new experimental method was studied. In a closed chamber, a test piece (30cm×30cm) was crushed by falling a brass ball (7.25kg) from 50cm height, and the samples were collected on a filter at 3 locations in the chamber. The concentra tions of released Asbestos fibers were measured using a phase contrast microscope. Five kinds of boards, [Silica Asbestos-Cement Board, Asbestos Cement Sheets (Flexible Boards, Flat Sheet and Corrugated Sheet) and Vinyl Floor Tile], were examined and releasing characteristics of the boards were estimated.All the test pieces except Corrugated sheets, werecrushed into four pieces, and had almost the same total breaking lengthes, therefore, the present method was considered to have good reproducibility. By studying the relations between the released Asbestos fib ers and bulk specific gravity of the boards, the following relationship was obtained.
F=245.1×exp (-1.745×A){r=-0.9357, r²=0.8755, n=19}
where F means released Asbestos fibers (10⁵ fb/ test piece), and A means bulk specific gravity (g/cm³) of the tested boards. As the boards of lower bulk specific gravity have lower strength, therefore, those are considered to be crushed easily, and to release Asbestos fibers easily.

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Thin copper film together with nitron, BaCl₂ and AgNO₃ films were exposed to the atmosphere for short time, i.e. for a half day and/or one day, at many sites in the southern part of Kyushu in Japan. Evaluation was made on the extent and appearance of corrosion caused by each ionic and gaseous species which erupted from Sakurajima volcano and deposited on the copper film. The following results were observed.
No secondary SO₄^2- particle was found in the deposited aerosol, but it was found as a sulfate connected with volcanic ashes. Thin copper films were more severely corroded by deposition of gaseous HCl and Cl^- than that of SO₄^2- and sea salt. The corrosions on the copper film were sometimes more advanced when exposed for a half day than for one day. It is suggested that a part of chlorine compounds such as gaseous HCl and Cldeposited as acid, and were neutralized gradually by gaseous NH3 in the atmosphere with the lapse of time.

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Annual changes of the pH of river and lake water in the mountainous region in central Japan were investigated by using the water quality monitoring data in Nagano prefecture from 1972 to 1989. By this analysis, the annual trend of the decrease of the pH of river and lake water was confirmed in the upper stream area of Saigawa, Himekawa and Tenryugawa (Matsukawa), where the bedrocks of their watersheds consist of acidic rocks such as the granitic rocks and rhyolite. However, such a decrease of pH of river water was not obvious in the upper stream area of Chikumagawa, Nakatsugawa, Tenryugawa (Koshibugawa) and Fujigawa, where their bedrocks consist of neutral rocks and basic rocks, such as andesite and basalt, and sedimentary rocks. The decrease of pH of rievr water was also not obvious in the middle stream area, where the influence of neighboring anthropogenic pollution was not negligible.

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[in Japanese]

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