Air purification/remediation technologies for removing hazardous pollutants emitted in the atmosphere are keenly sought in order to improve the air quality in large cities, although it is difficult to efficiently capture such pollutants that are transported and diffuse rapidly. Recently, a passive method based on photocatalysis is proposed for energy-and labor-saving air purifjication by removing low-level nitrogen oxides under the sunlight. In this review, air purification methods utilizing plants (trees), soil, adsorbents, and flue gas deNO_x methods are surveyed and the requirements for practical purification systems are discussed together with the principle of the photocatalytic method, fabrication and characterization of prototype air purifying materials, performance at polluted roadside, and future prospects.

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A wind tunnel study of peak concentrations in the near-wake region of a cubical model was conducted. Tracer gas was emitted from the rooftop at the center of the model and was measured with a fast-response concentration detector. The results showed that there were two dispersion regimes in the building wake. One regime, labeled the “mixing regime”, was approximately below the middle of the buiding. The other regime, designated the “intermittency regime”, was approximately above the middle of the building. In the mixing regime, the peak of the concentration spectrum were observed in a low frequency region, while, in the intermittency regime, the peak appeared to shift to wards a higher frequency region. The gust factor (G_f) near the building wake has a considerable scatter range of G_f=3-20. On the other hand, the peak factor has a small scatter range of 4-7. The relationship between the peak factor (P_f) and averaging time (T_a) can be expressed by the equation P_f = 9.1 T_a^-0.46 in the range of T_a =1-200s, where T_a is the time in prototype time.

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High concentration of O₃, SO₄^2- and NO₃^- over the East Asia is examined by the 3-D long-range transport model and the field observation conducted on May 1987. It was revealed that 1) intermittent transport of pollutants strongly correlated with the passage of synoptic scale high/low pressure system, 2) the numerical model explained well the major time variation of O₃, SO₄^2- and NO₃^-, 3) SO₄^2- and photochemical fraction of O₃ had a quite similar spatial and temporal variaitons, 4) tropospheric intrusion of stratospheric O₃ played an important role for the high O₃ concentration at the surface.

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The thermal environment was investigated with one-dimensional urban canopy model. In the model, the arrangement of buildings in several ‘km’ square, which corresponds to one horizontal grid in the meteorological mesoscale model, is simply parameterized with the mean width of the buildings, mean width of the roads and distribution of the height of the buildings. Averaged sensible heat flux from the roof, wall and road is separately estimated through heat balance equation over each surface. Anthropogenic heat sources are able to be distributed at each level. When all the building height was 33 m and both width of the buildings and roads were 30m, the air temperature at 3 m high rose by 1 K during afternoon to evening. When narrower roads were used, the temperature increased more in the daytime, but decreased at night. The temperature rise near the surface was greater with buildings than that without buildings, and also greater in case that the heat sources were located near the surface than located near the top of the buildings, when actual daily variation of the anthropogenic heat near Tokyo station was given.

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As well known, it is increasing consumpton quantity of gasoline that is refined from crude oil as fossil fuel. It is necessary to restrain consumption quantity of oil because oil is fewest mining possible years in figure resources as 46 years, also quantity of cars is increasing and emitted gas arise from combustion of gasoline happen serious emvironment problem because it causes an air pollution. The authors watched ionization radial rays that high rays is famous to bring various obstacle against the human body but low rays is of benefit, and we made sheet that combustion efficiency of internal combustion engine used of “Zuibyougan” is “stones and rocks” emit low ionization radial rays. It was able to get good results that improvement of fuel efficiency of automobile and reduction of monoxide, hydrocarbon and black smoke in discharge gas sed of this seat.

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It has been known that the environmental carcinogens, such as polycyclic aromatic hydrocarbons (PAH), form DNA adducts in exposed tissues. The relationship between the lung cancer and environmental exposure is expected to be clarified by the analysis of DNA adducts in the lung tissue which may be the main target tissue after exposure to the environmental carcinogens. The ³²P-postlabeling high-performance liquid chromatography (³²P-HPLC) method is expected to be useful for the analysis of the DNA adducts in human lung tissues, due to its high sensitibvity and high resolution. The object of this study is to determine the effectiveness of the ³²P-HPLC method for the analysis of human lung tissue. The DNA adducts in lung tissue from 11 autopsies were measured by the ³²P-HPLC method. The chromatograms in all cases showed plural peaks after the DNA adducts mixtures separated. The peak pattarns were different from each other suggesting the difference of history of exposure. Two peaks with the retention time, 56.4 and 62.4 minute, were commonly observed among some cases. Although the compounds corresponding to these peaks could not be specified, the cases with such peaks may be exposed to the same compounds. From these results it can be concluded that through the ³²P-HPLC method which was used to study the DNA adduct in human lung tissue, can be used to evaluate not only the TAL, (Total DNA Adduct Level) but also the type of exposure to environmental carcinogens.

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On July 18, 1997, EPA promulgated new standards for fine particles, with PM_2.5 as the indicator (15μg/m³, annual average; 65μg/m³, 24-hour average). EPA also retained the existing levels of the PM₁₀ standards (50μg/m³, annual average; 150μg/m³, 24-hour average) to pro-. tect against exposure to coarse particles. This decision was based on an extensive review of the scientific information regarding effects of PM. The upper 50% cut point of 10μm was chosen because it provides a measure of thoracic particles (i.e., those particles entering the lung). The 50% cut point 2.5μm was chosen to divide thoracic particles into fine and course particles because of their differences in sources, composition, and properties (chemical, physical, and biological). The time required for determining compliance or noncompliance with the revised PM standards is such that the next periodic review of the PM standards (required every 5 years) will take place before new particle control measures will be required. Monitoring requirements for determining compliance and research needed for the next review have been identified by EPA. Research needs include improved measurement techniques for finemode particles.

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