New nitrated polycyclic aromatic hydrocarbons including dinitropyrenes (diNPs), dinitrofluoranthenes (di-NFs), and dinitrobenzo (a) pyrenes (diNBPs), were discovered and were tested for mutagenic and carcinogenic action.
The diNPs 1, 3-, 1, 6-and 1, 8-diNP mutated Salmonella typhimurium his-TA98 at the frequencies of 81.4 to 261 revertants per pmol, and were widely distributed in diesel emission particulates and airborne materials as the major mutagen. Rats given 1, 6-and 1, 8-diNP significantly induced malignant fibrous hystiocytomas in the local site by subcutaneous injection.
In addition, 3, 7-and 3, 9-diNF discovered were potent mutagen in the Salmonella microsome assay system, and carcinogen in the lungs of rats. The lungs of rats given each compound significantly induced squamous cell carcinoma at the minimum dose level of 50 μg per rat. It was also found that both compounds induced micronuclear polychromatic erythrocytes in the femoral marrow cells in mice. These results suggest induction of chromosome aberrations or chromosome damage.
There was a relationship between NO₂-substitution of benzo (a) pyrene (BP) and the mutagenic potency of nitro-BPs. The nitrated BP substituted at the 3 position onthe chemical structure of BP was quickly reduced by rat liver microsomes in the presence of NADPH or NADP as a cofacter, and converted to nitroso and amino derivatives. It was found that the reducing ability of nitro-BP is associated with carcinogenicity in rats: 3, 6-dinitro-BP but not 1, 6-dinitro-BP was tumorigenic in the local site by subcutaneous injection into rats. These results are important for detecting chemical mutagens/carcinogens which are emitted in completein combustion of fossile fuels.

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We meausred N₂O of exhaust gas from 9 stationary sources. As the results, N₂O concentrations from the gas boilers were very low and less than about 5 ppm, even then low excess air ratio. In case of municipal refuse incinerator, the concentrations were the extent of several 1-20 ppm. And the amount of N₂O from refuse incinerators was about 70g per 1 ton municipal refuse. The total emission from muiucipal refuse incinerator in Japan is estimated to be about 2, 400 ton a year.
In case of sewage sludge incinerator, N₂O concentration of exhaust gas was the extent of several tens-100ppm and more than NO on the contrary. And the amount of N20 from sludge incinerators was about 400g per 1 ton sludge cake. The total emission is estimated to be about 1, 240 ton a year in the same way as the above plant.
Subsequently we surveyed the formation of N₂O on the various conditions by using a laboratory combustion apparatus. It became clear that N₂O depended on N content in kerosene. At gas burning test, N₂O formation was very low level.

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Recent studies regarding the chemistry of sulphur compounds in the atmosphere were reviewed and evaluated in terms of the significance of sulphur compounds in the formation of acidic rainwater. The review includes the processes of emission of SO₂, gas-and aqueous-phase oxidation of SO₂ to sulphuric acid and wet and dry deposition of sulphur compounds. Evaluation of studies concerning a proportional relationship between SO₂ emission and sulphuric acid wet deposition was an especially major purpose of the review. A number of field and modeling studies have shown that the limitation of oxidant of SO₂ would give rise to a non-proportional relationship between SO₂ emission and sulphuric acid wet deposition because the conversion of SO₂ to sulphuric acid in the atmosphere is dependent on the availability of oxidants of SO₂, such as H₂O₂. The nonproportional relationship between SO₂ emission and the wet deposition of sulphuric acid complicates the development of an efficient acid deposition control strategy. For example, 50% reduction in SO₂ emission from industrial sources may not necessarily lead to a 50% reduction of sulphuric acid wet deposition, but it may result in a somewhat smaller reduction.

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