In general, plants are highly sensitive to many air pollutants, and show acute or chronic injury according to concentration and duration of their exposure. Abundant researches on effect of air pollution on plants can be found since the early 20th century.
Outline of the related works in Japan was reviewed historically referring to literatures in Europe and America.
Before World War II, acute injury of plants by higher concentration of sulfur dioxide or others was investigated, and several diagnostic techniques for plant injury by such a pollutant were reported until 1970. After 1970, indicator plants for photochemical oxidants and others were screened, then the minimum concentration of the pollutants at which plant injury occurs and also the effect of combined pollution were studied. Recently, effect of air pollution by photochemical oxidants or acid precipitation on vegetation in large area is being investigated.

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The reaction between triethanolamine (TEA) or monoethanolamine (MEA) and 0₃ had been investigated by an ozone generator, an ozone automonitor, a gas chromatograph, and a gas chromatograph-mass spectrometer.
The reaction products had been analyzed and the reaction order had been calculated from the kinetic data. For MEA-0₃ system, the reaction order was equal to 0 with respect to O₃ concentration and the main product was HCHO. For TEA-0₃ system, the order with respect to O₃ concentration was equal to 1 and the main product was also HCHO, although C₃H₇CHO, C₂H₅CHO, C₂H₃CHO, and CH₃CHO were produced at the same time.

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By using a manganese dioxide tube for selective decomposition of ozone, nitrogen dioxide and ozone can be simultaneously determined by luminol chemiluminescence method. The activity of manganese dioxide for the decomposition of ozone is stable for more than one month. The detection limit for NO₂ and O₃ is estimated less than 1 ppb and the standard deviation for 5 measurements of NO₂ at 10 ppb and 0₃ at 100 ppb were 2.1% and 1.1%, respectively.

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The most convenient methodology for air quality impact assessment is the application of computer prediction model. Many prediction models use Gaussian Distribution Model as a theoretical foundation along with the practical experience of case studies to establish a simplified model. Due to the local scale, simplified model seem to be more effective for presenting the specially regional character such as topography and meterooligical factors. That is, field data for the height dependent parameters can be collected in enough number through experiment and modelized, which is very useful for increasing the representation and accuracy of the prediction model.
This paper will review the tracer experiment and empircial data of effective stack height for the large point source characteristic dispersion at the 4 coal/oil fjired-power plants in the Western region of Taiwan since 1980, and draw a conclusion in the modelization for the diffusion parameters and effective stack height. Author also compares the suggested experimental model with the foreign major power equation/linear chart, which gives a study on new methodology for tracer experiment.

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In order to elucidate the change process of atmospheric mercury from metallic mercury to divalent inorganic mercury, oxidation of metallic mercury by H₂O₂ and Cl₂ in aqueous solution was investigated.
In the reaction system of Hg^O-H₂O₂-Meⁿ⁺ twelve metallic ions other than Fe³⁺ scarcely oxidized mteallic mercury. However, in case Fe³⁺ existed with H₂O₂ in the solution, oxidation of metallic mercury was enhanced in proportion to the each concentration. The reaction was first order with H₂O₂ and Fe³⁺. And it was inferred that metallic mercury was oxidized by hydroperoxy radical (·OOH) which was formed through the interaction of H₂O₂ and Fe³⁺.
Oxidation rate in the reaction system of Hg^O-ClO^- was considerably greater than that in the above system. The equilibrium concentration of dissolved mercury was proportional to that of ClO^- and the molar ratio of both components agreed with the stoichiometric ratio of Hg^O/ClO^- in the system of Hg^O-ClO^-. The reaction was zero order with ClO^-, that is, the reaction rate seemed to be independent of ClO^- concentration. And author presumed that it was due to the extremely prompt rate of reaction with which metallic mercury was oxidized by ClO^- and HClO in the aqueous solution.
These results suggested that oxidation of metallic mercury by H₂O₂-Fe³⁺ and ClO^- (HClO) would took place in cloud and rain water.

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Personal exposure concentrations of nitrogen dioxide (NO₂) were measured for volunteers living in Tokyo, Bangkok and Manila, who were raised from sceintific researchers and their families, by NO₂ Badge for one week in February, 1983. At the same time, NO₂ concentrations in indoor and outdoor air of their homes and offices were also measured by NO₂ Badge. In addition, staying time in various living environments were also surveyed for each volunteers.
The personal exposure concentrations for volunteers living in Tokyo ranged from 13 to 132 ppb and its mean value was 37.7 ppb. On the other hand, the mean values for volunteers living in Bangkok and Manila were 12.2 ppb and 13.6 ppb, respectively, only one third of that of Tokyo. Distribution patterns of the personal exposure concentrations were also different in Tokyo and the other cities, that is, the distribution in the former was followed on a logalithmic normal distribution and the one in the latter a normal distribution.
In Tokyo, indoor NO₂ concentration (mean value 47.6 ppb) was very higher than outdoor NO₂ concentration (mean value 21.0 ppb), and correlation between both the NO₂ concentrations was not recognized. On the contrary, in Bangkok and Manila, indoor NO₂ concentration (Bangkok: 10.4 ppb, Manila: 12.6 ppb) was lower than outdoor NO₂ concentration (Bangkok: 12.5 ppb, Manila: 14.0 ppb). Furthermore, it was found that indoor and outdoor NO₂ concentrations in both cities were correlated well each other, respectively.
The times spent indoor home for volunteers in Tokyo, Bangkok, and Manila were all longer than half a day, that is, 13.6, 13.4 and 14.3 hours a day, respectively, and the time for housewives in Tokyo was 21.5 hours a day. Mean total time staying indoors was longer than 20 hours a day in every city.
NO₂ personal exposure concentrations estimated from indoor and outdoor NO₂ concentrations agreed relatively well with the measured NO₂ personal exposure concentrations.

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On an average of long term sampling, difference ΔC of ground level concentration of NO₂ between a street side and that of 100 m away from the street in an urban area must be explained by a few parameters. We analyzed NO₂ concentra tion data which were sampled around the urban street during the total number of 28 days, 7 days a month and 4 months long in all.
The following simple empirical formula was obtained from a regression analysis of the data.Δc=Q (a/W-e) Q: nitrogen oxides emission from motor vehicles on the street W: street width a, e: empirical parameters
The prediction by the formula agree well with the observation.(R=0.93, significance level<0.01). The formula and our study will be useful for the practical prediction of NO₂ concentration.

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