The concentrated sulfuric acid mist is formed by evaporation of sulfuric acid in a calciner heated above its boiling point 338.8°C, or by the chemical equilibrium kept in the furnace or automobile engine in which fuel containg sulfur is burnt, and is exhausted into the atmosphere.
The mist particle composed of concentrated sulfuric acid has the toxic character due to its strong dehydrating action for protoplasm and may cause the various diseases of the respiratory organs.
The concentration of sulfuric acid in mist formed by the conventional atmospheric oxidation of sulfur dioxide, on the contrary, so dilute that the mist particle has no dehydrating toxic action. Compared to the concentrated sulfuric acid mist, the gaseous sulfur dioxide and nitrogen dioxide are less toxic.
Therefore, they may be considered to be the index substances of the degree of air pollution caused by the concentrated sulfuric acid mist in some cases.
The acid mist particle in the atmosphere is easily detectable by means of the Acid Mist Detecting Plate.
The most effective remedy is the desulfurization of fuel oil used for boilers or Diesel engines.

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Airborne dust samples collected on glass fiber filters by high volume air samplers were treated with benzene extraction and silicagel column chromatography. The polycyclic aromatic hydrocarbon (PAH) fractions were determined by hydrogen flame ionization gas chromatography with a glass capillary (G-SCOT) column. By using a computerized gas chromatography (with the same capillary column)/mass spectrometry system, 31 PAH were identified. The isomers (e. g., benzo (a) pyrene, benzo (e) pyrene and perylene) and the derivatives (e. g., methylfluoranthene and methylbenzo (ghi) fluoranthene) could be efficiently resolved on the G-SCOT column. Overall recoveries were 93.3 to 101.6% for the less volatile PAH than benzo (b) fluorene and 64.2 to 87.7% for the others. By this method, concentrations of 13 PAH in airborne dust collected in the Kitakyushu district were estimated.

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A simple reaction model of NO, NO₂, O₃, which can be easily combined with a general atmospheric diffusion model, has been presented. In this model, the common constants estimated directly from smog chamber experiments has been used without modification.
In the atmosphere near the source, conversion form NO into NO₂ can be explained by only two or three chemical reactions. One of the characteristics of these reactions is the chemical conservations of (NO+NO₂) and (O₃+NO₂). By taking advantage of these conservations, the diffusion equations have been separated from the chemical reacton equations. Then the concentrations of NO, NO₂, O₃ have been calculated by an approximation method.
The results as follows:(1) This approximation method has been in a good agreement with a more complex numerical model.(2) A comparison of the result of the method with observation data measured near the highway and also that with those of plumes from large souces have made satisfactory concordant results.

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During 42 days from 23 July to 3 Sept., 1976 (1008 hr), simultaneous measurements of gaseous and particulate sulfur concentrations in the atmosphere were made at our laboratory. By examining the results of the measurements in relation to meteorological conditions, the following information was obtained concerning the behaviors of gaseous and particulate sulfur concentrations at the observation site. Gaseous sulfur concentration was strongly dependent upon the wind direction being much influenced by SO₂ gas coming directly from large sulfur emitting sources. Against this, particulate sulfur concentration was relatively weakly dependent upon the wind direction. On hot and fine days, conversion of SO₂ gas to particulates is promoted through oxidation by photochemical reaction, and fine particulates thus produced are accumulated in the atmosphere because of the long residence time. Gaseous sulfur shows larger variation in concentration than particulate sulfur. A periodicity was clearly found for the gaseous sulfur concentration being caused by the alternation of land and sea winds, but no clear periodicity was found for the particulate sulfur concentration. Correlation coefficients within 24 hr between gaseous and particulate sulfur concentrations were not so large as expected, and ranged from 0 to near 1 depending on the meteorological conditions.
It should be noted that the features of the atmospheric sulfur behaviors stated above are peculiar to the observation site. The circumstances are different from site to site. The analytical method used in the present study would be effectively applied to grasp the features of the atmospheric sulfur behaviors at various sites.

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The reduction of nitric oxide with carbon monoxide on various catalysts supported on γ-alumina was investigated by using a flow reactor under atomospheric pressure and temperaturefrom 80° to 500°C.
The effects of NO, CO, O₂ concentration and space velocity on the reauction were studied.
The results obtained were as follows;
1) The effectiveness of rare earth metal oxides was recognized, CuO·Nd₂O₃, CuO·Dy₂O₃, CuO·Pr₆O₁₁, CuO·HO₂O₃ catalysts were especially effective as compared with CuO catalyst at relatively low temperatures.
2) With CuO·Dy₂O₃ catalyst, NO conversion was not affected by the excess CO more than 650%.
3) With CuO·Nd₂O₃ catalyst, NO conversion was little affected by oxygen if 50% of O₂ quantity required for CO oxidation was added, however, it was largely affected if 80% of O₂ was added.
4) The reduction mechanism of NO with CO appears to be attributed to a redox reaction, i.e., oxidation-reduction cycle, on the catalyst.

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