Strongly acidic rain (pH 2.86) was observed in Maebashi in June 26, 1981. The rainwater contained H⁺ (1380μequi./l), NH₄⁺ (21.2 ppm), Ca²⁺ (2.9 ppm), Na⁺ (0.74 ppm), K⁺ (0.74 ppm), Mg²⁺ (0.31 ppm), SO₄^2- (46.8 ppm), NO₃^- (95.3 ppm) and Cl^- (13.5 ppm). The total cation concentration was 2778μequi./l and approximatelyequal to that of total anion (2893μequi./l). Sixty samples of acid rain were divided into two groupsin terms of concentration (μequi./l), namely NO₃^->SO₄^2- and SO₄^2->NO₃^-. The hydrogen ion and othercomposition concentration of the rainwaters in the group of NO₃^-> SO₄^2- were clearly higher than those inthe group of SO42-> NO3-. In the group of NO₃^->SO₄^2-, hydrogen ion concentrations were proportionalto NO₃^- and NO₃^-/SO₄^2-, especially under pH 3.50. For reasons as above mentioned, it was presumed thatthe rain was acidified particularly with HNO₃.

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Factor analysis was made for interpretation of aspects of three-to six-ring polycyclic aromatic hydrocarbons (PAHs) in the ambient air by using concentration of atmospheric PAHs (C_PAHs), temperature, solar radiation and wind velocity as variables. The variables were determined in Osaka City from November 1977 through November 1978. The number of variables and data were 12 and 28, respectively. Three major common factors were extracted for the interpretation in the preliminary loading matrix obtained by the principal factor method because cumulative percentage of contribution of the factors was 91.5%. A final loading matrix was obtained by using the varimax method. The pollution aspects of PAHs in the ambient air could be successfully explained by using the three common factors. The first common factor (70.8% of contribution) was estimated as an item of dilution of PAHs. The variation of C_PAHs in the ambient air was found to depend mostly on dilution by air movement. The second factor (9.58% of contribution) was estimated as an item of decomposition of PAHs mainly caused by photochemical reactions in the ambient air. The third common factor (11.2% of contribution) was estimated as an item of contamination mechanism of PAHs in the ambient air. This factor suggested that the ambient contamination of the lower vapor-pressure PAHs were mainly caused by combustion of fuel, and that the higher vapor-pressure PAHs were emitted by both combustion of fuel and vaporization from materials containing PAHs.

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The concentration of nitrogen dioxide (NO₂) is often observed to be lower indoors than outdoors, in case of no internal emission source of NO₂. This suggests the constant removal of NO₂ by interior materials.
NO₂ sorption into several interior materials was examined. Tatami-omote, or rush carpet commonly used in Japanese house, sorbed appreciable amount of NO₂, when compared with the other materials: cotton cloth; woollen cloth; fusuma paper; shoji paper. Tatami-omote is likely to be contributing most to elimination of NO₂ gas indoors.
As a mechanism of sorption or elimination of NO₂, the possibility of microbial denitrification, or reduction to molecular nitrogen, was examined for rush carpet. Denitrification occurred only under anaerobic condition with ample water present. Thus it is unlikely to occur in actual environment.
More reasonable explanation is still required for the continuous sorption of NO₂ without appreciable accumulation of nitrite and nitrate in rush carpet. This suggests some kind of chemical reaction capable of removing the nitrogen of sorbed NO₂ to air is working on rush carpet.

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Relative intensity of three emission lines were determined for various low pressure mercury lamps. Photochemical reaction in the NH₃-O₂-N₂ system under the UV irradiation was studied under atmospheric pressure at room temperature. The rate of NH₃ decomposition was not related with the intensity of the 253.7 nm or 194.2 nm emission line but proportional to the relative intensity of the 184.9 nm emission line. The constants in the equation:-d [NH₃]/dθ=k₁ [NH₃] +k₂ [O₂] ^1/2 (θ=W/F, W;electric power of lamps, F; gas flow rate) are proportional to the intensity of the 184.9 nm emission line of these lamps. k₁' and k₂' values in the following equation are independent of the kind of these lamps:-d [NH₃]/dI=k₁'[NH₃] +k'₂ [O₂] ^1/2 (I=relative intensity of the 184.9 nm emission line/F). Then, NH₃ decomposition efficiency was evaluated by the measurement of the intensity of the 184.9nm emission. Decomposed NO_x was 0.77 times that of NH₃ in NO-NH₃-O₂-N₂ ([O₂]; 10%) under the irradiation with various low pressure mercury lamps. The decomposition rate of NH₃ was 1.25 times larger than that in NH₃-O₂-N₂. Since O₃ formation in the O₂-N₂ system is proportional both to the NH₃ decomposition in the NH₃-O₂-N₂ system and to the NO removal in the NO-NH3-O2-N2 system with the use of the same lamps, the efficiency of the lamp for NO_x removal in the NO-NH₃-O₂-N₂ system was evaluated by measuring the efficiency of O₃ formation.

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Daily 3-hour exposure of rats to 1.0 ppm O₃ for 30 consecutive days resulted in an increase in pulmonary flow resistance which was suspected to be dependent primarily on the narrowing of relatively large airways. The suggestive reduction in lung distensibility was also observed, but a change in pulmonary static volume-pressure curve indicative of altered refractive forces of alveoli was not observed. Light-microscopically, a marked formation of the mucosal infolding was noticed particularly at larger to middle-sized bronchi, and the increased secretion frequently covered the inner surface of the mucosa at the top of infolding: thus, their effective caliber appeared to be narrowed. No significant change in the resistance of peripheral airway was detected by the present technique in the same animals. Daily 3-hour exposure to 1.0 ppm O₃ for 14 consecutive days resulted in no significant change in the functional measurements.

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Physiological, morphological and biochemical effects of intermittent exposure to 0.5ppm O₃ on rat lungswere studied. After daily 6-hour exposure during 60 consecutive days, a result suggesting the increase in peripneralairway resistance was obtained by the measurement of the flow resistance at different levels of elastic pressureof the lungs which were left in situ in the thorax after sacrifice. However, no significant change in COuptakewas observed. Various morphological alterations were light-microscopically discernible at the wideregion of airways: particularly noticed was the evident increase of secretions at the peripheral airway regions.On the other hand, the lung biochemistry including the content of GSH and the activities of related enzymesshowed no substantial change. No meaningful difference in the above respiratory effects was observed betweenanimals of 2 different ages (4 and 10 weeks old at the beginning of the exposure), and between animalswith and without pre-exposure to 2 ppm O₃ for 3 hours.

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Wet scrubbers have been widely utilized for controlling dust and hazardous gas from stationary sources. There are, however, many troubles such as filter breakage and dealing of mist drain encountered in sampling effluent gas stream from such scrubbers.
We have developed a new stack sampler for dust or mist in such cases. The sampler is equipped with an impactor and a mist reservoir in front of a thimble filter. Larger particles including mist are separated by impaction against the impaction plate and smaller solid particles are filtered through the thimble filter. Both the dust samples are weighed respectively after the mist drain are evaporated and the thimble filter are heated at the temperature range of 100-110°C or about 250°C.
The collection efficiency of the sampler was calculated using the data by Ranz and Wong (1952) and measured using polydisperse mist particles of di-octyl phthalate having a mass median diameter (mind) of 1.5μm and water with 11.5μm mind. The diameter of the jet nozzle was determined to be D_c=φ2mm, and the clearance ratio, which is the ratio of the length between the jet nozzle and the impaction plate for the jet nozzle diameter, was experimentally determined to be R_c=4. The impactor can separate more than 50% of particles having a mind of 1.5μm for the suction rate of more than 8l/min. On the other hand, the improved impactor, in which the lawn mesh, a special kind of filter media, is coated on the surface of the collection plate, can separate more than 50% of particles with 1.5μm mind for the suction rate of more than 4l/min, and also separate more than 90% of particles with 11.5μm mind for the wide range of the suction rate of more than 1l/min.

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The photochemical reaction of SO₂ with cis-2-butene in the presence of O₂ has been investigated.
The reaction products were immediately methylated with a solution of diazomethane in ethyl ether and then analyzed by a gas chromatograph and a combined gas chromatograph-mass spectrometer.
The product mixtures were found to be a malodorous, acidic, pale oily substances which were soluble in water and some organic solvents. These methylated products found to be (CH₃O)₂SO, (CH₃O)₂SO₂, C₄H₈SO₂, C₄H₇SO₂CH₃, plus some unidentified substance.

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Atmospheric mercury was measured by continuous monitor of Nippon Instruments Co. Ltd. Mercury AM-1 model used the collection by gold amalgamization method and the analysis by cold flamelesss atomic absorption spectroscopy.
The distribution of atmospheric mercury was investigated at four locations (commercial, background, mercury deposits and mercury deposits' neighbourhood areas) in Nara Prefecture, which have different environments. The two former were measured for 30 minute period and the two latter were measured for 1 hour period.
The amount of atmospheric mercury collected at the commercial area ranged from 1.89 to 16.40ng/m³, and the mean value and standard deviation was 5.12±2.12 ng/m³ (n=92). On the other hand, at the background area ranged from 1.87 to 3.87ng/m³, and the mean value and standard deviation was 2.54±0.50ng/m³ (n=45).
The hourly deviation of atmospheric mercury concentration at background area was so little compared to the commercial area.
The behavior of atmospheric mercury concentration at commercial area showed similar to CO, NO₂, NO_x and SO2 concentration, and moreover, the correction between atmospheric mercury and them showed strong correlation (r=0.606-0.742, n=80: CO, n=92: NO₂, NO_x, SO₂). From this, atmospheric mercury was estimated to generate combustion systems. All fossil fuels contain 0.002-2 ppm mercury themselves, and almost of them are used to combustion energy. The mercury in fossil was estimated to emit to atmosphere together with NO₂, NO_x, SO₂ and CO.
As to meteorological conditions, atmospheric mercury was not correlated with them. As there was no stationary generated origins as destruction plant and large factory near the sampling point of commercial area, no characteristic tendency was not shown to wind direction.
The behavior oaf tmospheric mercury concentration in basin as Nara showed high in night and low in day. This is estimated to the stability of air in a similar manner as concentration of NO₂ and other air pollutants emitted in burning systems. From this, it is evident that atmospheric mercury is estimated to emit from the combustion system.
The mean value and standard deviation of atmospheric mercury concentration at mercury deposits area was 142.82±93.87 ng/m³ (n=136), and the maximum value was over 350ng/m³ and even minimum value was over 30ng/m³. On the other hand, these value at mercury deposits' neighbourhood area apart 650 m from mercury deposits area was 13.29±9.46ng/m³, and the maximum value was 47ng/m³ and the minimum value was 3.87 ng/m³.

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