To investigate how oxalic acid behaves in the atmospheric aerosols, we collected the aerosols with an Andersen sampler in Chiba city for 6 years from April 1987 to March 1993, and analyzed oxalic acid and several inorganic ions. The particle size distribution of oxalic acid was bimodal with one peak at 0.5 to 1μmand another at 4 to 5μm. The fine particle peak under 2μm was larger than the coarse particle peak over 2μm. The distribution pattern did not change throughout the year. Fine particles occupied 65 to 70% of all oxalic acid.
The concentration of oxalic acid in the atmosphere ranged from 0.17 to 0.79 μg/m³ (average of 0.38μg/m³), and was high in summer and low in winter. Values obtained at sampling sites along main roads in an industrial area did not differ from those at a rural area, where sampling sites were far from main roads. The monthly variation of oxalic acid concentration differed from that of inorganic ions (nitrate, chloride, ammonium and potassium ions).
Oxalic acid seems to behave like other dicarboxylic acids, which are considered to be secondary products of the photochemical reactions. The atmospheric temperature and insoluble duration may be related to the generation and diffusion of oxalic acid since the seasonal variation of the concentration of oxalic acid in TSP was similar to that of temperature. This suggests that oxalic acid gas is produced by photochemical oxidation of vegetative and motor exhaust hydrocarbon emissions, and oxalic acid gas may aggregate to particles.
Oxalic acid are quite important both as an ion component of particles and as an index for the secondary organic particles in the air.

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Bronze and polished bronze plates (thickness of 5 mm, width of 35 mm and length of 70 mm) were exposed for one year at three indoor and outdoor sites, which were located on a mountain top, on a mountain foot and by highways. The corrosion weight (mg/dm²) of bronze plate was apparently larger in comparison with that of copper plate. Dissolved ions from the plates by rain were determined during every exposure period. Copper, zinc and lead were relatively more leached into the washed solution. Then, by alloy nature, bronze was found to be easily ionized comparing with copper. It is suggested that the formation of the corrosion products at an early exposure period is affected mainly by gaseous air pollutants, and the dissolution of the corrosion products is easily caused by acid rain.
The surface of the polished bronze plates was analysed by X-ray fluorescent spectroscopy after the exposure of the plates for one year, and high concentrations of sulfur, chlorine and silicon were detected from the surface of the sample C at highway site.
The formation of sulfate and copper (I) oxide was observed on the surface of the corroded bronze plates by Fourier transform infrared spectrophotometry and X-ray diffractometry, but the formation of nitrate and copper (II) oxide of was not so much observed.

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We measured the instantaneous concentration of sulfur dioxide in ambient air by using the conductometric method. Conductometric analyzers were set up at air monitoring stations in Japan. The hourly averages of concentrations of sulfur dioxide were measured at these stations. To maintain these analyzers, it is necessary to manually exchange the absorbents. The UV-fluorescent analyzer is a compact alternative method of measuring sulfur dioxide concentration, and it does not need complicated maintenance. However, it is very expensive to monitor sulfur dioxide concentration in many places with this method. Some researchers have reported the instantaneous measurement of sulfur dioxide concentration using a conductometric analyzer, but their methods cannot be used at low concentrations (a few ppb). We have developed a system that measures the concentration of sulfur dioxide instantaneously by making use of a personal computer. We analyzed the correlation between the conductometric and UV-fluorescent methods by varying the accumulation time. From these results, we found a fairly good correlation between sulfur dioxide concentrations measured by two kinds of analyzers and the best accumulation time for calculating the concentration defined as-0.5 ppb difference in sulfur dioxide concentration by using the conductometric analyzer. Our calculation method can be used even at low concentrations of sulfur dioxide. At higher concentration, our method can measure the concentration of sulfur dioxide instantaneously within a minute.

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In order to evaluate the effects of air pollution around main arterial roads with heavy traffic on the respiratory symptoms of schoolchildren, a cohort study was performed in primary schools in Chiba Prefecture.
The schoolchildren were observed from 1992 through 1994. The prevalence and incidence of asthma were compared for three goups: subjects residing within 50 meters of the main arterial roads in urban areas; subjects residing over 50 meters from the roads in urban areas and subjects residing in rural areas.
For all three years, the prevalence of asthma was highest in girls residing within 50 m from the roadsides, and the girls in rural areas had the least prevalence. In boys, this trend was found only in the second year. The incidence of asthma in the two-years period was 5.7% in boys residing within 50 m from the roadsides, 3.9% in boys residing over 50 m from the roads, and 1.6% in boys residing in the rural areas. The incidence of asthma in girls were 3.3%, 2.5%, and 1.0%, respectively. The multiple logistic regression analysis was perfomed to determine the adjusted odds ratios. In boys, the adjusted odds ratios for the incidence of asthma, relative to subjects in rural areas, were 3.70 in subjects residing within 50 m from the roadsides and 1.92 in subjects residing over 50 m from the roads. In girls, the odds ratios were 5.97 and 2.44, respectively.
These findings suggest that air pollution around main arterial roads increases the incidence of asthma in schoolchildren.

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The traffic congestion and the air pollution in Bangkok are serious problems, because the transportation system depends on only the automobiles. In this paper, the number of automobiles, the road network, the examples of traffic congestion and the energy consumption of transportation system in Bangkok are introduced.
The measurement results of total suspended particles, carbonmonoxide and lead concentrations in the atmosphere at some monitoring sites along road side are shown. The policies of Royel Thailand Government on the countermeasures for the automobile exhaust gas are the improvement of transportation system and the fuel of automobile, and equipment of the catalytic converter for passenger cars.
The prediction results of the improvement for the air pollution at road side due to the automobiles are introduced by adopting various scenarios.
Furthermore, the author has introduced the plans of new electric railroad constructions, and shown the examples of improvements for the road structure and traffic control in order to solve the traffic congestion and the air pollution in Bangkok.

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