Decomposition of trichlorofluoromethane (CFC-11), which has been regarded as a cause of ozone destruction, was carried out by r.f.plasma. The decomposition of CFC-11 increased with input power of plasma, and decreased with gas flow rate of Argon. Products were soot, halogenated methanes and ethanes, molecular halogens etc. Addition of H₂O made the decomposition increase as high as 100%. Both CO and CO₂ appeared by the addition of H₂O, while both halogenated hydrocarbons and soot were extraordinarily decreased. Effect of O₂ addition was almost the same as that of H₂O addition. Addition of H₂ affected no neither the decomposition nor depression of soot formation. Products distribution between halogenated ethanes and ethylenes, however, was affected by H₂ addition. Reaction pathways to products were discussed based on change in Gibbs energy.

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Many kinds of chemicals are contained in exhaust gas from municipal waste incinerators, and some of them show mutagenicity.
In this study, sampling and extraction methods of mutagenic compounds in the exhaust gas were investigated in the Ames mutagenicity test. The exhaust gas was sucked at 2l/min for 1-2 hours, and the mutagenic compounds were colected by means of apparatus composed of a condensing bottle and a silica wool column. Hexane, ethylacetate, acetone, dichloromethane and methanol were used as solvents for extraction of mutagenic compounds. Among these solvents, ethylacetate was the most effective on extracting mutagenic compounds. Mutagenic compounds in the condensed water were extracted with 20ml ethylacetate for 5min. Mutagenic compounds in the silica wool column were dissolved in 20ml ethylacetate at the flow rate of 3ml/min, and the compounds adhering on inlet pipe of the condensing bottle were rinsed with 2ml ethylacetate every tern times. Ethylacetate of 40ml was added to the above solutions in the condensing bottle, and the compounds adhering on inner wall of the bottle were extracted completely. All the ethylacetate solutions were mixed, dehydrated with sodium sulfate, and evaporated. The residues were dissolved again in 5ml of dimethylsulfoxide (DMSO), and their mutagenicity was bioassayed by the Ames test.

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Effects of soil acidification on the growth of Japanese cedar seedlings (Cryptomeria japonica D. Don) grown in andosol, red-yellow soil and brown forest soil were investigated.
One week before transplanting the seedlings, 10, 30, 60 or 100meq H⁺ as H₂SO₄ solution was added to 1l of soil. The H⁺ was not added to the control soils. The seedlings were grown in the artificially acidified soils or the control soils in a greenhouse for 12 weeks from June 9 to September 1, 1992.
The dry weight growth of the seedlings grown in the three soils for 12 weeks was reduced with increasing amount of H⁺ added to the soils. However, the extent of the growth reduction in red-yellow soil and brown forest soil was greater than that in andosol.
In the three soils, the p H (H₂O) decreased and the water soluble Mn and Al concentrations increased with increasing amount of H⁺ added to the soils. The Al concentration in roots of the seedlings grown in artificially acidified soils was remarkably high.
It is concluded that the growth reduction of Japanese cedar seedlings induced by the addition of H₂SO₄ solution to the soils is greater in red-yellow soil and brown forest soil than that in andosol. The growth reduction is closely related to the decrease of soil pH and the increase of Al concentration in soils and roots.

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The effect of NO_x and HCHO emission changes in the atmosphere by the introduction of methanol fueled vehicles are computed under clear and cloudy sky winter conditions. The target area is Tokyo Metropolitan Area. The model used in this study is a box model. The methanol vehicles introduction scenario, which means the full conversion of diesel trucks and buses into methanol trucks and buses, is compared to actual present day scenario. Under methanol vehicles introduction scenario, NO_x emission is expected 15% lower, and HCHO emission is assumed three times higher than present day scenario.
With the introduction of methanol vehicles, NO_x concentration under clear and cloudy conditions should be 8.0% and 8.1% lower than present day, respectively. Nitrogen dioxides reduction rate is very low, 1.5% for under clear sky and 0.7% for under cloudy sky due to rapid reaction of NO oxidation with background O₃. However, comparing with same NO_x emission scenario, NO₂ concentration might be increased by 1% because of OH or HO₂ radical increase with HCHO emission increase.
Because of photochemical reaction are weakened in winter season, and using higher HCHO emission factor of methanol vehicles, HCHO concentration under clear and cloudy conditions should be 21.0% and 40.5% higher than that of present day, respectively. The relationship between HCHO emissions and atmospheric concentrations as ibvestigated in this study, has been determined to be linear. From this observation, under cloudy winter conditions, to attain the same average HCHO concentration when methanol vehicles introduced, the amount of HCHO should be under 1.09 times as that of present day. It can be concluded that, the HCHO concentration in the atmosphere would not be increased by the introduction of methanol vehicles in the Tokyo Metropolian Area, in cloudy winter, if the emission factor of methanol trucks and buses should be under 0.036 (g/km) (0.058 (g/mile)) and 0.05 (g/km) (0.08 (g/mile)), respectively.

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A device, which safely and readily generates low concentration of gaseous hydrogen fluoride (HF) in the laboratory, was fabricated. In the device, HF gas was generated by mixing of Na F solution with H₂SO₄ solution, and was separated from the solution by using porous polytetrafluoroethylene (PPTFE) tube as a permeation tube. Under the excess H₂SO₄ condition, concentrations of HF were affected by Na F concentrations in the solution, flow rates of purified air and the solution, and temperature.
By keeping the flow rate of purified air and the temperature around this device at constant, the low concentration of HF gas (20-700 ppb (v/v)) could be obtained in proportion to Na F concentration in the solution under the excess H₂SO₄ condition.

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This study was performed to determine the effects of long-term exposure to low levels of ozone (O₃) on airway responsiveness in guinea pigs. The animals were exposed either to filtered air or 0.2ppm O₃ for 9-10 weeks. Airway responsiveness to intravenously indused (iv) or inhaled aerosolized methacholine (Mch) was then determined. When Mch was administered iv, the O₃-exposed guinea pigs showed airway hyperresponsivcness. Infusion of 1 and 2μg/kg Mch for 5minutes resulted in a decrease of Grs (resp; ratory conductance) to 82 and 62% of that seen after the infusion of saline, respectively. In contrast, in the air-exposed animals, these doses of Mch reduced Grs only to 94 and 84% of that seen after saline infusion. The opposite was seen when Mch was administered by aerosol: the O₃-exposed guinea pigs were hyporesponsive. Specifically, the aerosol administration of 100, 200 and 400mg/ml of Mch to O₃-exposed guinea pigs resulted in a decrease of Grs to 96, 85, and 71% of that seen after saline administration, whereas these doses of Mch reduced the Grs of air-exposed animals to 75, 53, and 42% of that seen after saline. These results suggest that long-term exposure to low levels of O₃ induces changes that tend both to increase and decrease airway responsiveness. These data support the hypothesis that changes in the muco-epithelial barrier of ozone-exposed guinea pigs attenuates the effects of enhanced sensitivity of airway smooth muscle to Mch after ozone exposure.

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