The present availability of automatic time sequence aerosol particle samplers, which use Nuclepore filters and are compatible with elemental analysis by PIXE, has led to the development and testing of computerized data handling and interpretation procedures. By time series analysis and other statistical approaches the sources and transport pathways of pollution and natural aerosol constituents may be inferred. Applications include both long range and urban scale transport of pollutants and natural soil dust. For example, Kosa dust events in Japan are found also to carry pollution sulfur which is probably derived from Asian mainland sources. The Kosa transport can be very long range, since its dust occurs over Hawaii typically during spring, representing transport up to 10, 000 kilometers from the deserts of China. A pollution sulfur component, apparently derived from Asian sources, has also been detected at Hawaii. On an urban scale, plume transport in St. Louis, Missouri, has been correlated with meteorological parameters by means of statistical analysis of titanium concentration data. The sources of lead are of several different types, both industrial and vehicular, as inferred by multiple regression analysis for inter-element correlations and spatial modelling based on wind rose diagrams of concentration. By these methods of receptor modelling of the urban aerosol a source apportionment for ambient air pollution can be made. The PIXE method, together with specially designed aerosol samplers, provides an economical and versatile approach to obtaining atmospheric concentration data amenable to interpretation by time series analysis and other statistical methods which are carried out with the aid of computers.

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A mathematical model was developed to simulate the diffusion process of pollutants from flat roadways in urban area, which satisfies the condition that wind profile is expressed by power law, and is a non-Gaussian type for vertical spreading of pollutants. The model and parameters were identified by using the field experimental data of parallel and oblique wind to roadway, for 3 areas for a flat surface (Loc. 1), an uncrowded section by buildings of about 12 meters height (Loc. 2), and a crowded residential section of about 6 meters height (Loc. 3).
An initial diffusion which of horizontal direction of pollutant was about 2 times of vertical diffusion width at Loc. 1. The reliability of simulated value of pollution concentration was examined for each category of wind direction, wind speed, distance from a roadway, and height of sampling point. The result is as follows:(1) The mean coefficient of correlation was 0.934 at Loc. 1, 0.884 at Loc. 2, and 0.891 at Loc. 3.(2) The ratio of observed value to estimatevalue of normalized mean concentration of SF₆ was 1.08. 1.49 and 1.53 at three areas respectively. The estimation was a good result at Loc. 1 but the mean concentrations were less than observed mean values at Loc. 2 and Loc. 3. The reason is due to a large value given to initial diffusion width of horizontal direction (σ_y0*). The ratio of concentration will be improved by changing σ_y0*.
As a whole, it was recognized that the model did not take place any systematic error due to the structure ofmodel.

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For 10, 843 population aged over than 40 years were dwelling in eight areas of Muroran City, Asahikawa City or Kamiiso Town in Hokkaido, the questionnairing about respiratory symptoms were conducted during 1970 and 1974.
In the present paper, we deal with the relationship between air pollution and prevalence of chronic bronchitis (CB) obtained from the survey.
Highly correlation between the symptom prevalence of CB and concentration of sulfur oxides measured by the lead dioxide (Pb0₂) method where used as the air pollution index in eight areas differed in the conditions of air pollution were recognized, and following regression line with two variableswere led: Y=3.87+4.21 X, where Y: the sex-, age-and smoking-adjusted prevalence rate of CB in percent, and X: the concentration of sulfur oxides measured by Pb0₂ method in mg S0₃/ 100 cm²/d.
The value from this fomula was excessively higher than that from Shimizu et al.'s obtained from their study in Osaka City in 1962-1963.
In at least three of seven areas being lower concentration of sulfur oxides than the levle recognized: clearly the health hazards from air pollution, the increase of the symptom prevalence of CB were noted.
Precise solution to the cause of higher prevalence in our survey could not be obtained, but it can be considered that the effects of the particular factors in the cold district (e.g. higher level of pollution in winter, cold climate, heating) appeared sensitively. Further study on the characteristic effects of air pollution to man in cold district is necessary.

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A morphological characterization of size-density-classified coal fly ash was carried out. Four types of fly ash from coal-fired power plants and a testing boiler in Japan and the Unites States, 1) white gray sample, 2) black sample, produced from the same coal by the same boiler, 3) high sulfur coal fly ash, and 4) fly ash mixedfired from coal and heavy oil were tested.
Sample was fractionated by three testing sieves (opening: 149, 74, 44μm) and five heavy liquids (1.6, 2.0, 2.4, 2.8, 3.2 g/cm³). The shape and color of particles were observed by a scanning electron microscopy and a transmission optical microscopy, respectively. The composition of particles was analyzed by an energy dispersive X-ray analyzer. The particles in the size-density-fraction were classified into typical shapes and colors.
Black sponge-like particles containing principally carbon are concentrated in the fraction of size >44μm, density 1.6-2.4 g/cm³, nonopaque angular particles containing silicon are in the fraction >74μm, 2.4-2.8 g/cm³, black surface crystallized particles containing iron or calcium are concentrated in the fraction > 3.2 g/cm³. Sample 1 is composed of lower density particles than sample 2 and sponge-like particles are not observed in sample 1. The rate of fraction >3.2 g/cm³ in sample 3 is 5.6% and is more than the rates of same fractions in other samples. The fraction is composed of surface crystallized particles enriched with iron. In sample 4, 10-30% of fraction >44 m, 1.6-2.4 g/cm³ is composed of fragments of spheres, but sponge-like particles are not observed in the sample. The rate of fraction 2.8 g/cm³ in sample 4 is only 0.8%.
Size-density-classification technique is powerful technique for characterizing coal fly ash.

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An attempt was made to evaluate the difference of lung cancer mortality in the 23 administration districts of Cental Tokyo. The records are classified into 552 sub-populations according to 3 categories: 12 classes of age, sex and 23 districts. In each population assuming the heterogeneity in their individual levels of mortality risk, the number of deaths have negative binomial distribution. From these assumptions, four hierachical models are constructed to assess the factors which are said to affect lung cancer mortality differencials. Factors in these models are the 3 categories noted above, birth cohorts and degree of diesel exhaust emissions in each district. First, as pointed out in many literatures, the importance of birth cohort effect on lung cancer mortality is recognized. Second, the marked difference on cancer mortality among districts is found: the district which has the highest effect differ more than 1.3 times from the lowest. Further more, in these districts a space clustering related to distriet effect is observed. These results seem to indicate an existence of some environmental factors affecting cancer mortality. So finally, as one of those factors, diesel exhaust of 23 districts are added to the model. The results of this model, however, do not show any significant effects of diesel exhaust emissions to lung cancer mortality differencials.

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Continuous measurement of light scattering coefficient was made with an integrating nephelometer in the urban atmosphere of Nagoya for about two years, keeping the relative humidity of the air less than 50%. Monthly averaged light scattering coefficients in the season of autumn to early winter were present in high values more than 3×10^-4 m^-1 and they were measured in the cases of wind velocity less than 3.0 m/sec. The diurnal variation showed that a maximum value of light scattering coefficient was measured at about 12 LST in the summer, while the variations in autumn and winter had two maxima during the periods of 8 LST to 12 LST and of 17 LST to 22 LST. No systematic diurnal variation was found in the spring.

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