Characteristic injury syptoms such as glazing, bronzing, and silvering have been ovserved on the lower surface of leaf beet, kidney bean, petunia, head lettuce, and some other plants under high oxidant emergence in the Tokyo Metropolitan area since 1972, and these symptoms which were clealy different from those due to ozone have been assumed to be caused by PAN. However, this assumption was not confirmed, for the exposure experiments with PAN have not been carried out in Japan so far. In an attempt to prove the case, therefore, a series of exposure experiments were conducted in a controlled-atmosphere exposure chamber equiped with artificial light apparatus, using PAN synthesized from ultraviolet irradiation of ethyl nitrite vapour in oxygen. As a result, the exposures of 6, -16 hours and 10 pphm PAN caused serious damage like caving with glazing or bronzing in caved lesions to lower surface of younger leaves, and in exposure tests with 20 pphm PAN injury symptoms were observed even on upper surface of leaves of plants. Further the leaves of white-flowered petunia were found to be most sensitive to PAN, i. e., damaged even by a 3 pphm exposure. Microscopic examinations showed that the PAN characteristically caused injuries of spongy cells and that these cells became collapsed and colored with brown. Leaf injury symptoms on herbaceous plants caused by synthesized PAN in the exposure experiments were found to be quite similar to those such as glazing, bronzing, and histological appearance of the damaged tissues on lower surface of leaves of such sensitive herbaceous plants as leaf beet, kidney bean, head lettuce, and others seen in the field under high oxidant emergence. Therefore, it seems that the said type of injuries to leaf beet, kidney bean, and head lettuce ovserevd in the field were caused by PAN.

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Air pollution control can be brought to accomplishment by the development of emission control methods, sampling and measurement of air pollutants and air pollution forecast.
The purpose of this study is to develop the system concept of statistical forecast for the daily activities of regional air pollution control.
In the present paper, the statistical model of the variation of air pollutant concentration is proposed by way of an example of SO₂ concentration and the validity of the proposed statistical model is verified through the analysis of correlograms of SO₂ concentration observed at the monitoring stations in Tokyo Metropolitan Government, Saitama Prefecture, Chiba Prefecture, Yokohama City and Kawasaki City.
The results are as follows;
(1) The mixed model of the synthetic type of periodical variations and the auto-regressive type is satisfactory for use as the statistical model of variation of air pollutant concentration.
(2) The correlograms can be classified into the nine patterns according to the three criteria: periodicity, persistencies of 24-hour period and 1-hour period. All of these patterns are considered to be the proposed statistical model.

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Atmospheric corrosion rates of carbon steel at 53 sites in Tokyo was studied. The corrosion rates were plotted in the map of Tokyo and the whole area of Tokyo was divided into three kinds of zones with the degree of the rates, large, middle and small. Large degree zones mostly corresponded to industrial and commercial zones, middle the surrounding areas and small zones western part (suburbs) of Tokyo. Also the degree of corrosion rates almost coincided with SO₂ distribution.
By means of correlation analysis method, corrosion rates were found to be mainly affected by temperature, SO₃ (PbO₂ method) and chlorides. From the data, the effect of environmental factors on corrosion rates were quantified by multiple regression analysis as shown below.
y=0.00774+3.86×10^-4 x1+2.45×10^-6 x2+3.24×10^-6 x3+3.22×10^-3 x4+2.40×10^-3 x5
where
y: Corrosion rate (mm/month)
x1: temperature (°C)
x2: surface wetness (hour)
x3: Electric conductivity of soluble precipitation (μυ/cm l·month·100 cm²)
x4: sulfur oxides (SO₃ mg/day·100 cm² PbO²)
x5: chlorides (Nacl mg/day·m²)

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Recently various attempts have been made to assess naturally occuring pollution loads and to identify specific “Smog” components by special planting of a specific variety of plant under more or less controlled conditions in Japan. Although it is restricted by law in Japan, cigar wrapper tobacco, Bel W₃ (Nicotiana tabacum, L) is excellent for this type of study for several reasons: It has been more intensively studied than any other photochemically sensitive species; it has an indeterminate growth habit during vegetative stages; mature leaves are most sensitive and show fairly uniform sensitivity at a given stage of growth; new injury is readily separated from old injury; its symptoms of oxidant injury are characteristic, easily identifiable and quite specific.
In this paper, we reported in summarizing many literature and experiments in relation between oxidants injury with tobacco Bel strain. This paper's descriptions classify into four large groups; outline of pure selection ofleaf spot-sensitive tobacco strain Bel W₃; difference of ozone torelance and shape of leaf spot among many Bel tobacco strains; the relation between ozone susceptibility of Bel tobacco strain and environmental conditions in growth; the relation between ozone susceptibility of Bel tobacco strain and chemical components in leaves.

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