In order to study the effects of air pollutants, especially photochemical oxidants, on the plant growth, the poplar cuttings (Populus x euramericana cv. ‘145/51’) were grown in filtered air greenhouse (F.A.) and non-filtered air greenhouse (n-F.A.) in the suburbs of Tokyo. In filtered air, about 90% of the ambient photochemical oxidants were excluded.
(1) The shoot's height (H), diameter (D) and dry weight of poplar cuttings was respectively 216 cm, 17.3 mm, 211.69 g in filtered air and 143 cm, 11.7 mm, 82.73 g in non-filtered air at about four months after cutting in 1975.
(2) Growth ratio (RGR) and net assimilation ratio (NAR) of poplar cuttings were less in non-filtered air than in filtered air, but leaf area ratio (LAR) was more in non-filtered air.
(3) Number of leaves unfolded till 114 days after cutting was 65.2 in filtered air and 51.2 in non-filtered air. The maximum leaf area of plant was 332.2 cm² in filtered air and 222.2 cm² in non-filtered air.
(4) The foliage damage was observed on the mature leaf surface of poplar cutting in the non-filtered air greenhouse when the ambient oxidant was over 10 pphm, but was not in the filtered air. The damaged leaves dropped in the growing season. The number of dropped leaf was 20.4 in non-filtered air, but only 5.0 in filtered air till 114 days after cutting in 1975.
(5) There was a strong negative relationship between the ratio of growth amount (D²H%=n-F.A./×100) and oxidant concentrations occurred in poplar growing season from 1974 to 1978. Farther, there was a strong positive relationship between leaf damage index and oxidant concentrations occurred from 1975 to 1978.

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The new developed method is examined for measuring out the Dustfall to the north, east, south and west, winds. This apparatus is constituted of the round cover with a fan shape hole for catching Dustfall and wind vane, four receptacles and the cylindical receiver. And it is able to separately catch Dustfall in each receptacles by this apparatus.
The amounts of Dustfall were measured using this apparatus and dust-jar at TOYOHARA Cho in HIRATSUKA City for four months. And Iron, Manganese, Lead and Nickel in Dustfall were determined.
However, the amounts of Dustfall measured by the new apparatus showed about two times to the dust-jar, they are summarized as follows.
When the wind blew from the east, the amounts of Dustfall were shown the maximum affecting from the industrial and urban area, and minimum amounts of Dustfall were shown in blowing southerly from the seaside. Within the limits of this experiment, it was able to suppose the source of Dustfall.

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Various kinds of dust monitor for monitoring dust emissions from chimneys and for evaluating the performanze of dust collectors have been developed and come into the market. These monitors are based on the principles of light transmission, light scattering, triboelectric effect (or contact electricity), beta attenuation, electric balance and so on, but they are hampered by each principle and construction.
Therefore, the informations on the characteristics and limitations of these monitors are very important and convenient for users who select or operate one of these and analyze the data obtained by these.
Beta attenuation type dust monitors have a merit that the beta radiation attenuation through collected filter samples is proportionate to the mass in general, i.e., the mass concentration of sample dust can be determined by measuring the mass of dust loaded paper filters and the volume of gas drawn through the filters.
Experimental results show the followings; the mass values of various kinds of dust measured by the instrument agree considerably well with those by a chemical balance, the ill-balanced dust loading on the paper filter affects largely on the value measured by the instrument, paper filters made of silica-glass fibers are recommended for sampling oil-fired dust since paper filters made of glass fibers absorb sulfur dioxide in flue gas.

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Aphysical measurement, as well as chemical analysis, of air pollutants is one of the most important research to clarify the effects of the pollutants on the human body, especially on the respiratory organs.
In this paper, numbers and sizes of the acid mist particles in the ambient air were investigated at the four sites near industrial areas for one and half years, and the following results were obtained.
(1) The observed numbers of the acid mist particles were in the wide range from 0 to 26, 700/m³, depending on the sampling times and sites.
(2) The diurnal changes in the acid mist particle concentrations are classified into seven types of categolies. Among them, the most frequently observed type, mainly in autumn and winter, was that the observed values of particle numbers were high in the morning and the evening and lower in the daytime.
(3) The observed sizes of the acid mist particles were in the range from 1μEm to 8μm, depending on the sampling times and sites. In most cases, the considerable part of all particles was occupied by the smaller particles of about 1μm.
(4) The diurnal changes in the acid mist particles size distribution are classified into eight types of categolies. Among them, the most frequently observed type was that all of the particles were less than 2μm and the distribution rate was not changed.
(5) In summer, the observed values of the acid mist particle concentrations were high and the minor particles occupied the main part of the size distribution.

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Suspended particles released from various boilers using different kinds of fuel (crude oil, heavy oil, kerosene, coal, wood and so on) were subjected to multielement analysis by means of instrumental neutron activation method and energy dispersive X-ray fluorescence spectrometry. Elemental concentrations in suspended particles were found to be strongly dependent on the kind of fuel. The analytical results were compared with those obtained formerly on suspended particles released from refuse incineration. Using the measured elemental concentrations in suspended particles released in oil combustion, the contribution of the oil combustion to the elemental concentrations in the urban atmosphere was roughly estimated, assuming that 90 percent of the vanadium in the atmosphere come from oil combustion. According to this estimation, in a particle size range below about 10 micron, the contribution of the oil combustion to the urban atmosphere is quite large for Ni, being as large as for V, and appreciably large for Co (-7%), Cr (-3%) and Na (-2%).

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The reliability of a quasi-steady state approach (QSSA) compaied to the Gear's method was examined by applying both methods to two detailed propylene photochemistry models. The same results were obtained when an upper limitation (SSLIM) was imposed on the concentration of steady state compounds used in QSSA. We developed a QSSA computer program QUALICS which was able to exchange automaticallly the steady state compounds exceeding SSLIM.

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