Three cultivars (Yukikomachi. Comet and White Cherish) of radish plants (Raphanus sativus L.) were exposed to 0.15μ1.1-1 O₃ for 4 h a day (10: 00-14: 00), five days during the exposure period of one week. The dry weight growth was reduced in Yukikomachi and Comet, but was not affected in White Cherish by the exposure to O3. The cultivar sensitivity to O₃ based on the dry weight growth and net assimilation rate was ranked as Yukikomachi> Comet> White Cherish. The net photosynthetic rate during an exposure to 0.15μ1.1-1 O₃ for 4 h reduced compared with the pre-exposure value in the three cultivars. The degree of reduction in the net photosynthetic CO₂ uptake per unit amount of O3 absorbed by their leaves during the exposure to O₃ was significantly different among the three cultivars, and was ranked as Yukikomachi> Comet> White Cherish. However, the absorption rate of O₃ in Yukikomachi was not significantly different from that in Comet nor White Cherish. From these results, it is proposed that the primary factor determining the cultivar sensitivity to O₃ based on the dry weight growth of radish plants is not the absorption rate of O₃, but the inhibition rate of net photosynthesis per unit amount of O₃ absorbed by their leaves.

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A method for determination of thiophenes and benzothiazole in tire treated pyrolyzates has been developed by means of a pyrolysis-GC equipped with a flame photometric detector. The main sulfur-containing pyrolyzates are thiophene, 2-methylthiophene, 3-methylthiophene and benzothiazole at 670°C using a Curie-point pyrolyzer. 3-Methylthiophene was the specific pyrolyzate from truck and bus tire tread. In the above determination of the tire tread pyrolyzates, sulfates and asphalt in airborne particulate matter interfered by pyrolytical generations of SO₂, thiophene, 2-methylthiophene and 3-methylthiophene. In this study, those sulfate and asphalt in the sample were removed by successive solvent extractions with deionized water and benzueeethanol (4: 1), respectively. These pretreatments were able to determine thiophene, 2-methylthiophene and 3-methylthiophene in tire tread pyrolyzates without the interferences due to sulfates and asphalt. Thiophenes in tire tread pyrolyzates in the atmospheric suspended particulate matter collected in early winter season were determined with our pnoposed analytical procedure and pyrolysis GC-FPD.

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The mutagenicities of both samples obtained by the personal samplers and the sanplers of airborne particulates in outdoors were compared, and the exposure-factors to mutagens were investigated. The personally exposed particulates were collected by means of the portable mini-pumps at a flow rate of ca. 1.5l/min for 24 hr, and the airborne particulates in outdoors were collected by a high volume air sampler at the same time. Four volunteers, two nonsmokers and smokers, were equipped with personal samplers, and were given the inqurity cards, which asked the numbers of cigarettes smoked, passive smoking and heating, during a week at each month of Feb., May, Jul. and Oct. in 1991. Organic components in airborne particulates were extracted by ultrasonication with dichlorometane. Mutagenic activities of these extracts were bioassayed for Salmonella typhimurium TM677 strain with and without S9mix using the ultramicro forward-mutation assay.
A significant correlation between the direct mutagenic activity levels and the number of cigarettes smoked was obtained from the personal data. From the comparison between the personal data of nonsmokers and the outdoor data, a good correlation was not obtained. The various factors such as heatings and poor ventilations enhanced the personal exposure level to airborne mutagens. These results suggest that the sampling and the bioassay technique are important to investigate, and evaluate the personal exposure to airborne mutagens.

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Emissions of N₂O and CH₄ exhausted from 10 municipal refuse incinerators in Tokyo have been analyzed. The refuse incinerators yielded N₂O emission levels of 1-20 ppm. And it became clear that N₂O concentrations of exhaust gas were dependent on furnace temperature. N₂O concentrations were almost constant at 25 ppm at below 700°C, less than 5 ppm at above 900°C. N₂O concentration tended to be in reverse correlation to NO_x concentration. These results were confirmed by laboratory experimental result that N₂O is unstable at the high temperature. N₂O emission levels tended to increase when modifications to lower NO_x emissions by urea injection or catalytic deNO_x method were employed.
CH₄ concentrations from incinerators with capacities of more than 150 ton per day were approximately 1 ppm. For relatively small incinerators, CH₄ concentrations sometimes rised to more than 500 ppm.

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Amounts of falling dusts and rain waters collected by the deposit gauge method were measured from April 1974 to March 1990 at 8 locations in Yukuhashi City.
The results showed that the amount of water-soluble matter decreased steadily year by year. A large percentage of pH values was within a range of 4.00-4.99, and yearly averages of pH value decreased steadily year by year. On account of dryness and prevailing westerly wind in winter, lime stone dust from the opencut mines and the cement factories reached Yukuhashi City, and pH of the reservoir water was neutralized partially.

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