Cancer of the stomach shows a characteristically high proportion in Japan. However, recently age ad justed death rate of lung cancer shows a marked increasing tendency. It is predicted that the death rate of lung cancer in man will become to the first ranking in 1990. The main causes of lung cancer are concerned to be cigarette smoking and some kind of foods. But, there is some recent concern that oxidant air pollutants such as O₃ and NO₂ also might be a contributing risk factor from some epidemiological data.
Here, we would like to discuss about the experimental data on effects of O₃ and NO₂ on lung tumor formation. These data show that O₃ and NO₂ increase incidence and multiplicity of lung tumors in mice. However, the data are not always statistically significant. Also it depends on experimental design whether ozone enhances or inhibits the development of lung tumors in mice. Similarly, ozone and nitrogen dioxide enhance lung colonization by cancer cells in jected intravenously following exposure to the air pollutants, whereas NO₂ kills lung metastases if cells are in jected prior to exposure. Both ozone and NO₂modulate the proliferation of pulmonary neuroendocrine cells, the precursor cells for small cell lung cancer. It is concluded that there is little evidence to implicate ozone or NO₂ directly as pulmonary carcinogens, but that they might modify and influence the carcinogenic process in the lung.

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A large amount of in jection-high performance liquid chromatography (HPLC) with spectrofluorometric detection was studied for analysis of the polynuclear aromatic hydrocarbons (PAHs) in trace suspended particle matters (SPM) collected by SPM monitor every 1 hour.
The procedures of this method were as follows: the sample solution was prepared to same composition of mobile phase (acetonitrile-water mixture, 80: 20, v/v) and then a large amount (usually 200μl) of sample solution was injected to HPLC. It was proved that this method could determine accurately and sensitively the 3 PAHs, benzo (a) pyrene (Ba P), benzo (k) fluoranthene (Bk F) and benzo (ghi) perylene (Bghi P).
The detection limits of PAHs by this analytical procedures in the case of 200μl in jection are 0. 063 ng/ml (absolute amount: 0.013ng) for Ba P, 0.072ng/ml (0.014ng) for Bk F and 0.71ng/ml (0.14ng) for Bghi P, respectively and the reproducibility of 3 PAHs are within 1.1% as expressed in terms of the relative standard deviation.
This method has been performed to prove the effectiveness of the trace analysis of 3 PAHs in SPM samples collected every 1 hour by SPM monitor utilized β-rays absorption method (suction rate: 18l/min, sampling time: 55min. 32 sec.).

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Indoor pollution with sprayed-on asbestos and abatement programs were discussed, especially focused on the recent survey for this problem in Japan and the case study for the asbestos removal in Kyoto university. The subcommittee of Kyoto university on asbestos confirmed the necessity for asbestos abatement programs because of the next three points, (1) there is no evidence that no-risk level for asbestos exposure exists, (2) the staff and students had been anxious about their health caused by asbestos exposure, and (3) the good indoor condition is desirable in the facilities for education and research. In the cafeteria in West campus and classrooms of Liberal Arts and Sciences about 2, 000 m² of ceiling and wall had been sprayed with asbestos which were severely damaged with areas missing, hanging loosely. For emergent abatement program these sprayed-on asbestos were removed being care of the room isolation using containment barriers, the appropriate use of respiratory equipment and so on.
Indoor asbestos concentrations with sprayed-on asbestos were almost equal to the concentration 0.6 f/1 of outdoor environment in the campus of Kyoto university if these rooms had been closed. But it is proved that the man's activity raises indoor airborne asbestos, 3.8 f/1 in case of workers' going in and out and 18 f/1 in case of air moving with fan. The asbestos fiber settling curve after removal was examined as empirical formula and the sufcient airborne asbestos reduction after removal were attained in almost one week. And indoor asbestos fibers after removal were reduced to the same level as the outdoor environment either closed or opened.

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The sensitive Ames test (the modified Kado microsuspension procedure) was applied to assess the mutagenicity of dust collected on filters in air conditioners. The major modification consists of using “amino acids enriched minimal glucose -agar base” developed by S. Arimoto to accelerate. growth of His⁺revertants and to shorten incubation period.
This procedure was approximately four to 18 times more sensitive than the modified Ames test (preincubation method by Yahagi et al.) for detecting mutagens in air particulate extracts and approximately four to 64 times more sensitive for the chemical mutagens, benzo (a) pyrene [B (a) P], 2-nitrofluorene [2-NF], 1-nitropyrene [1-NP] and 2-aminoanthracene [2-AA].
By using this method, it was able to obtain His revertant colonies of observable size after 18-24 h of incubation at 37°C.(48-72 h of incubation is required in original Ames test.)
The modified procedure was applied to assess the mutagenicity of dust collected on filters in six air conditioners in our institute. Dust in smoking room generally showed higher mutagenic activity than those in the other rooms (laboratory for atomic absorption spectrometry, laboratory for gas chromatography, laboratory for analysis of pesticide residues and so on).
It was suggested that the mutagenic activity, tar content and B (a) P content were generally related with the frequency of using fire.
Microsuspension procedure is applicable in testing sample of limitted mass.

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Coal, coal ash and airborne particulate matter were analyzed for tellurium by graphite furnace atomic absorption spectrometry after coprecipitation with arsenic. The use of tellurium as a tracer of coal combustion effluent was investigated in the comparison of behaviors and concentration levels of selenium in the atmospheric samples. Enrichment factors of tellurium in these samples against earth's crust or soil composition normalized by aluminium, the size distribution of tellurium bearing particles in the atmosphere and the molar ratio of selenium and tellurium showed a possibility of the use of tellurium as a tracer of coal combustion effluent. This hypothesis was also supported by the fact that tellurium was not determined in oils but in coals. This idea was tested by field experiments in Seoul, Korea where much coal is consumed particularly in winter season, and Yokohama, Japan where is of low level of coal consumption throughout year. The result of observation of tellurium concentration in the atmosphere at both sites showed a probable correlationship between concentrations of tellurium and coal consumption; a clear peak in both tellurium concentration and coal consumption in winter time in Seoul, whereas no characteristic patterns in Yokohama.

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In order to propose an allocation method of ambient air monitoring stations not only from the air pollution control point of view but also from the economic point of view, first a sensitivity analysis of the multiattribute utility functions for the optimal allocation of stations was conducted by varying four attribute values, which were assessment items for the allocation of stations. It was found that the hypersensitive attributes were both the number of ambient air monitoring stations and the percentage for covering of wide area. Secondly, two alternatives on the allocation of monitoring stations were derived based on the result of sensitivity analysis. The expected utility values of these alternatives were much higher than the value of the exsisting allocation. Then the preferential relation was examined in due consideration of the divergence of decision makers' opinions. As a result, the optimal allocation of ambient air monitoring stations was selected.

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Centrilobular emphysemas were induced in mice (ICR/Jcl, female) by inhalation of papain (a proteolytic enzyme contained in Papaya fruit) aerosol. Then, these mice were exposed to Cr₂O₃ dust (4.45±0.27 mg/m³, 2.4±1.7 μm) for 5 hrs. Average amount of deposited dust in the lungs of emphysema-induced mice was about 70% of that of control animals, immediately after the exposure. Whereas the clearance of dust was reduced in emphysema-induced mice, amount of residual dust in the lungs of emphysema-induced mice were higher than that of control at 6 months after the dust exposure.

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A diffusion model for particulate matter was developed, and source contributions in Kashima area, Ibaragi prefecture were calculated.
The model includes not only industrial sources but also the sources such as, straw burning and sea salt particle which had not been taken into consideration in previous simulation study. As for soil and secondary particle which were not easily calculated by diffusion model, contributions were estimated by the chemical component analysis and added to the calculated concentration by diffusion model. Emissions were classified into 4 groups (particle size 0-2, 2-10, 10-20, 20 μm-) and concentration smaller than 10 μm were compared with observed values of airborne particulates (suspended particulates and suspended dust).
The coincidence between observed and calculated concentration was satisfactorily good. Moreover, the intercept of the regression line whose gradient was 1.0 (A₀) was evaluated as 3.6 μg/m³, and about 90% of observed concentration was simulated by the present model.
Source contributions by diffusion model were compared with that by receptor model (CMB method), and the problems in the application of these two models were discussed.

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