Carbon monoxide (CO) is the most abundant air pollutant after carbon dioxide (CO₂). Usually CO is treated as an inert species in the “air pollution” of an urban area. However, in a global sense CO is very important because of its effects on atmospheric chemistry. Specifically, CO is partly responsible for controlling the hydroxyl radical (OH) concentration in the troposphere.
A simplified chemistry model was developed to incorporate the CO-CH₄ chemistry into a global transport model of these species. The model includes photodissociation rate coefficients expressed as functions of solar zenith angle and altitude.
The sensitivity of the OH concentration to some trace gaseous species, e.g., NO_x, O₃, and H₂O, was investigated using the model. In addition, the concentrations and diurnal variations of both OH and HO₂ and the contribution of individual reactions to OH generation and consumption were calculated.

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Effects of ozone, the major component of photochemical oxidants, on apparent photosynthesis, transpiration and diffusion resistance were investigated for attached leaves of rice, corn and bean plants. Ozone absorption rate of leaf was measured by assimilation chamber method, and the interrelationships between ozone absorption rate, transpiration rate and stomatal diffusion resistance were investigated. A simple gas diffusion model was adapted for ozone absorption mechanism of plant leaf.
The results onbtaied were as follows:
1) Decrease in apparent photosynthetic rate during ozone fumigation was mainly caused by stomatal closure. The degree of stomatal closure by ozone varied with plant species: Rice was most sensitive to ozone, corn and bean were less sensitive in turns.
2) Observed values of ozone absorption rate by attached plant leaf agreed satisfactorily with the values calculated from gas diffusion model by the assumption that ozone concentration in gaseous phase of surface of leaf mesophyll cell is zero. Therefore, it was shown that ozone absorption rate of plant leaf is controlled directly with the gas diffusion resistances, mostly, the stomatal diffusion resistance.
3) Ozone absorption rate was repressed by stomatal closure during ozone fumigation. It might be possible that the difference in stomatal responces to ozone influences the degree of the oxidants damage on plant growth, through the quantity of ozone incorporated into leaf.
4) The relationships between ozone concentration and ozone absorption rate was linear in the region of low ozone concentration. Whereas, in the region of relatively high ozone concentration, ozone absorption rate showed the tendency to saturate by the stomatal closure during ozone fumigation.

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A colorimetric method for determination of formic acid in the ambient air is presented. It is based on Grant's, that is, formic acid is reduced to formaldehyde with magnesium and hydrochloric acid, and the formaldehyde is determined by the chromotropic acid method.
Water is used as sampling medium. The collection efficiency of water for formic acid is ca. 100% when 750 μg/m³ of formic acid gas is passed through 50 ml of water in a train of two fritted bubblers for 10 min. The pre-sent method is not interfered by other carboxylic acid, formaldehyde, ozone, nitrate, and nitrite. Carbonate which interferes for partial formation of formaldehyde during reduction, is purged by adding acetate. Sampling volume of air should be relatively large to gain the sufficient amount of formic acid for analysis because the reduction rate is very low (apparent rate is 16.3%). Calibration curve is quasi-linear between 0 and 18μg/ml with 2.8% of relative standard devn.
The average concn of formic acid in downtown Kobe from 9: 00a. m. to 3: 00 p. m. on 5 days during July 1978, is 6.9μg/m³

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An attempt was made to modify the general time-concentration-absorption equations for alfalfa proposed by Thomas and Hill on the sulfur dioxide fumigation treatment. The original equations, t (C-0.24) = 0.94, t (C-1, 4) = 2.1 and t (C-2.6) = 3.2 when percentage of leaf destruction was 0, 50 and 100, were modified as t (C-0.24) = 0, t (C-1.4) = 1.1 and t (C-2.6) = 2.3 respectively. Moreover, the original was discussed for generalization and utilization.

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Suspended particles released from various small facilities, such as metal melting furnaces, heat treatment furnaces for metal oxides and pulverizers, were subjected to multielement analyses by means of instrumental neutron activation method and energy dispersive X-ray fluorescence spectrometry. Elemental concentrations in suspended particles were naturally quite varied depending on the kind of facility. In order to make it easy to grasp the contribution of suspended particles from a facility in question to the nearby atmospheric environment, the elemental concentration ratio, C_R, of the suspended particles to the typical atmospheric aerosol particles, was calculated and used as a measure of pollution contribution. The geometric means of elemental concentrations, which were obtained on the basis of the results of multielement analyses of airborne particulate samples collected in 110 residential areas distributed all over Japan, were adopted as the elemental concentrations of the typical atmospheric aerosol particles. It is quite natural that the values of C_R are high for the elements which are enriched in the materials handled in the facility in question. It is noteworthy that considerably high values of C_R were found for some elements which were not the main constituent elements of the materials handled.

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