In an environmental assesment, there are many small sources with an initial plume spread. In these cases they are often treated as an area source. There are several methods used for the prediction of concentration patterns from an area source.
1) Integrated finite line source method.
2) Imaginary point source method.
3) Integrated infinite line source method.
In this paper, two new practical models for a rectangular shaped area source are developed. These models are derived by integrating the Gaussian plume model approximately. In this process, an area source is replaced by an equivalent imaginary line source. The position of the imaginary source movesaccording to the downwind distance and stability.
These models are applied under the following conditions: 1) initial vertical spread; 2, 5m, 2) effective stack height; 1-50m, 3) stability class; A, D, F, G, 4) 1km×1km area source.
These models show the quite satisfactory agreement with the numerical integration method. These are also applicable for the oblique wind case by using the Gaussian plume approximate modelof a line source for oblique wind. And it has also shown that the proper usage of these models enables us to use much less calculating time than that of the integrated finite line models.
Finally the effective standards for these models usage are shown.

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A study was made of the distribution models approximated to the cumulative frequency distributions about daily mean sulfur dioxide concentrations.
The candidate models are Normal, Log-normal and Weibull distributions which are easy to apply and have two parameters respectively, and were examined fitness for observations by following three methods. These are that of using probability papers, AIC method and the standard deviation of differences between observed and estimated values.
It follows from the results that Log-normal model was the best in the three, that were considered, with the exception of the one part of the analysis.
Besides, the ranges and the annual variations of estimated parameters were found for Log-normal and Weibull distributions by the observed data in Japan. It is suggested that these values maybe used as factors of air pollution control.

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Atmospheric gaseous mercury was automatically measured by a mercury air monitor. After filtering, mercury was trapped with gold-coated Chromosorb W and successively eluted by heating the Chromosorb and then detected by the cold vapor atomic absorption spectrometry. SO₂, NO_x and six trace elements (Fe, Mn, Zn, Pb, Cd, Ca) collected by a high volume air sampler were measured simultaneously with mercury.
A significant correlation between the concentration of mercury and those of SO₂, NO₂ and trace elements was found.
The amounts of mercury and other elements emitted from the major sources, i.e. iron steel factory, coal-fired and oil-fired power plants, were estimated, and then the concentration ratios of each element to mercury were calculated. We modified the equation having been used for calculation of percent contribution to atmospheric aerosol to calculate the percent contribution to atmospheric mercury by means of the concentration ratios of each element to mercury both in the atmosphere and for the sources.
The results of practical calculations indicate that the contribution from the iron steel factory is larger than those from the coal-fired and oil-fired power plants in the sampling stations.
These analytical results were discussed in relation to the coefficient of fractionation and selection of index elements.

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Field experimental data for suspended particulates near a highway were analysed to estimate the emission by road traffic. In the experiment, suspended particulates (particulates smaller than 10μm), total suspended particulates, size distribution and nitrogen oxides concentrations were measured at four or five points near the road. The measuring points were located at 10, 50 and 100 meters from the road. The suspended particulates, total suspended particulates and size distribution were measured by piezo-electric or light scattering method, hi-volume air sampler and Andersen sampler, respectively. The nitrogen oxides concentrations were measured by chemical luminescence method.
The hourly data showed high correlation between NO_x and suspended particulates. From the proportionality of the two substances, emission coefficients including automotive and roadbed effects are figured out as follows:
E_{p, L}=1.60 g/km/truck: for trucks and buses
E_{p, s}=0.32 g/km/car: for passenger cars, mini-size cars and light rrucks
The data of size distribution of suspended particulates showed also proportionality between NO_x and coarse particulates greater than 2 μm. The estimated emission of TSP by vehicles are
E_{TSP, L}=2.08 g/km/truck: for trucks and buses
E_{TSP, s} 0.42 g/km/car: for passenger cars, mini-size cars and light trucks
The piezo-electric data agreed very well with the hi-volume and also with the light scattering data.

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Parmelia tinctorum of epiphitic lichens were fumigated for 48 hr with sulfur dioxide (0.1-0.3 ppm) and nitrogen dioxide (0.06-0.88 ppm) singly and in combinations. The effects on chlorophyll content, catalase activity and peroxidase activity of the fumigated frond were compared with those of the control.
Catalase activity and chlorophyll content decreased markedly by the fumigation with SO₂, and increased by the fumigation with NO₂.
Peroxidase activity increased by the lower level of SO₂ (0.1-0.2 ppm), and decreased in the higher level of SO₂ (0.3 ppm), and decreased by NO₂.
In the case of lower concentrations of the SO₂ and NO₂ mixtures, the effects of one gas on the chlorophyll content and enzyme activity were counteracted in the presence of another gas.
In the higher concentrations of the mixtures, the effects of SO₂ on chlorophyll content and catalase activity were accelerated synergistically by NO₂ mixed with SO₂, and the effects of NO₂ on peroxidase activity were enhanced by SO₂ mixed with NO₂.
Visual symptoms of damage were observed at the higher level of SO₂ and NO₂. SO₂ and NO₂ caused bleaching or necrotic areas and pinkish spots on the thallus respectively.
Visual injury was enhanced by SO₂×NO₂, and the symptom was more analogous to that of SO₂ than NO₂.

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It is important to get informations on size distribution of air borne particulate matters to investigate their emission sources, transportation process, and behavior in the atmosphere. The Andersen impactor has been generally used as a size selective sampler for this purpose, but the operation of this sampler is not very simple, and is not easy if analysis of all 8 stage samples and a back up filter was required to know a size distribution. This paper presents a simple and economical technique of collection of aerosol particles by the use of two filters in series in an idea to separate sample particles into two groups, fine and coarse particles. Another advantage of this technique is that the particles collected on filters can be directly analyzed without any physical or chemical procedure by X-ray fluorescence method.
Two Nuclepore filters of 47 mm in diameter set up to a commercially available sequential filter holder are placed in series at the pass of air flow for sampling. The coarse fraction (>2 μm) is collected on the first filter (pore size, 8 μm), and the fine fraction (<2 μm) on the second filter (pore size, 0.4 μm) at the air flow rate of 20 l/min. For the evaluation of proper fraction, the Two stage filter sampler was operated simultaneously with a conventional Andersen impactor. No significant difference was observed between results by two samplers. The results demonstrated that the Two stage filter sampler can be usefully applied for the fractionated collection of fine and coarse particles in the atmosphere.
The X-ray fluorescence method was effectively applied for analysis of the samples collected by the present method. Eight elements, Al, Si, S, K, Mn, Fe, Ni, and Zn were determined in each fraction of particles collected by 4 hours sequential sampling using the Two stage filter sampler, at Hiyoshi, Yokohama. Informations on the variation of elemental concentrations of aerosols at short time period could be obtained by the use of the present method.

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A system was developed for exposing cell cultures to the gaseous photochemical reaction products. The gaseous photochemical reaction products was produced by photochemical reaction of a hydrocarbon-NO₂-air system using the evacuable photochemical smog chamber. Quantitative analysis of gaseous compounds in the chamber air was done in situ by a long-path Fourier transform infrared absorption spectroscopy. In order to expose cell cultures to the gaseous photochemical reaction products, a system was designed and constructed in which monolayers cultured in culture square bottles are being rotated by an apparatus of roller bottle culture. Cell cultures of Chinese hamster V 79 cells were exposed to the photochemical reaction products of propylene plus NO₂ (initial concentrations of propylene: NO₂; 0.5 ppm: 0.25 ppm, 1.0 ppm: 0.5 ppm, 2.0 ppm: 1.0 ppm, and 3.0 ppm: 1.5 ppm) for 2 hr and toxicity was measured as inhibition of cell growth 24 hr after exposure. Growth was inhibited at all concentrations used in this study.
The system described was found to be effective for investigating the gaseous photochemical reaction products for cultured cells.

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The relationship between diesel engine operating conditions and a quantity of emitted benzo (a) pyrene in diesel particulate matter produced under the incomplete combustion was examined in comparison with mutagenic assays. Throughout this study, YANMAR NSA 40C diesel engine (4-stroke, single-cylinder, displacement; 269 cc) was utilized. The engine was operated under a constant revolution (2000 rpm) with a variety of loads (0, 250, 500, 750, 1000 watt) and was loaded by a connction of a electric resistance with a generator. Particulate sample were collected on a glass fiber filter (20.3×25.4 cm) using a collection apparatus, in which total exhaust gas introduced diluting with prefiltered air. The filters containing the particulates were Soxhlet-extracted with benzene (100 ml) for 8 h, concentrated to 10 ml. The extracted benzo (a) pyrene was quantitated by using a high performance liquid chromatography equipped with fluorescence detector. Mutagenic assays of the extracts of the exhaust particulates were carried out by the procedure of Ames et al. Throughout the previous experimental runs, fuel consumptiom, exhaust gas volume, particulate quantity in the exhaust, quantity of benzo (a) pyrene and mutagenic activity toward load were examined. A certain correlation was observed between the quantity of benzo (a) pyrene and the mutagenic activity had the minimum values at 500, 750 watt, respectively. Mutagenicity might correlate to the quantity of benzo (a) pyrene in the range of below 500 watt and increase in the range above 500 watt because of increase of mutagens other than benzo (a) pyrene.

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