In relation to atmospheric environment, I have studied two different research fields "Field sampling of atmospheric aerosols" and "Air purification techniques for organic gases." In this paper, the outline of these researches are introduced based on field sampling of atmospheric ultrafine particles near the emission sources using a new developed inertial filter (INF) sampler, and investigation of effective treatment for VOC gases and their decomposition products using combined advanced oxidation process (AOP) techniques.

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Concentrations of Nitrogen Oxide(NO_X) and Non-Methane hydrocarbons(NMHC) that are the precursor substances of ozone are lower than the national average in the Fukushima prefecture. However the ozone concentration exceeded 120 ppb at Iwaki City (coastal region) in the Fukushima prefecture on 4 August, 2006. To investigate the causes of the high ozone concentration appearing in this coastal region, we analyzed the relation between the appearance of the high ozone concentration and meteorological elements. As a result, it was discovered that the high ozone concentration appeared over the coastal region in the following situations: 1) An anticyclone appeared over Japan and a subsidence inversion layer formed. Therefore, the vertical dispersion of ozone was reduced. 2) A heat low developed over the Chubu mountainous area , thereby a southwesterly wind prevailed over the Kanto region and the coastal region. Therefore, the long range transport of ozone from the Kanto region to the offing of Fukushima prefecture occurred due to the southwesterly wind. 3) A sea breeze circulation prevailed in the coastal region under weak pressure gradient conditions with the anticyclone, and the ozone transported from the Kanto region to the offing was transported from there to the coastal region by the sea breeze. 4) The high ozone concentration was lifted from the ground to the upper part of the mixing layer by convective mixing and the sea breeze circulation. Therefore, the ozone, of which the concentration was higher than that observed at the ground, existed in the region during the night. 5) During the day time, the concentration of ozone in the coastal region increased more than that of the previous day due to adding the ozone that was transported from the Kanto region and that which existed in the upper part of mixing layer.

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The difference in fuel economy and emissions among vehicles meeting different emission regulations (ERs) was tested using a chassis dynamometer. The vehicle which meets the 1978ER, and ones that meet the 2005ER were examined. The results under the certification test conditions showed emission trends similar to a previous study for several vehicles which satisfied the 1978ER or the 2000ER. Several driving cycles were used in the test focusing on the ratio of the idling condition. In spite of the fact that the vehicles meet different ERs, the improvement in the fuel economy was from 25% or more at the average speed of around 9km/h to around 2% at 29km/h. As for the emissions, CO and HC increased but did not exceed the ER value during the low average speed driving cycle while NOx decreased. Based on the test, we proposed that if you use a vehicle which meets the 2005ER, you can do "no idling" action for the sake of conserving the global and local environments. The vehicle equipped with an automatic "no idling" action is desired to become widespread, because it had a better fuel economy and lower emissions than the others. Even if the vehicles meet the same ER, there are differences among the emission performances, and there is a case that the emission by the vehicle with the "no idling" operation is less than that with idling. In order to improve the real-world environment, it is important that such information is open and easily accessible by consumers.

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Carbon monoxide (CO) emission amounts in China are inversely optimized with Green's functions method, CO vertical profile measurements from MOPITT satellite instrument, and the GEOS-Chem chemical transport model (CTM) for the recent 6 years (2005 - 2010). Observations from surface sites (JMA and NOAA/GMD) are used for independent validation of a posteriori emissions. Model simulations with a posteriori emissions successfully reproduce the CO outflows from China to East China Sea and the Japanese archipelago in winter and spring, and compensate the under-estimates over the central eastern China region, considerably. A posteriori emissions in China exhibit significant seasonal variation in which the seasonal peak and bottom are found in winter-spring and summer, respectively. The CO emission in March is on average 54 % higher than in August. This seasonal cycle is consistent with other recent studies. Chinese CO sources obtained by the inversion are 164.5, 171.5, 180.8, 160.3, 152.5, and 156.1 Tg/year for 2005-2010, respectively, presenting inter-annual variations due to socioeconomic conditions (e.g., controls on pollutant emissions by the 2008 Beijing Olympic game and the global depression in 2009).

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Beech declines in the Tanzawa Mountains located in the northwest part of Kanagawa prefecture has been a serious environmental problem since the 1980s. One of the reasons of this decline is the high ozone (O₃) concentration level frequently observed over the Tanzawa Mountains. No large emission sources of primary pollutants involved in the O₃ generation are located around the Tanzawa Mountains, and photochemically formed O₃ due to the primary pollutants emitted from the downtown Tokyo and Kanto area under sea-land breeze circulation could be an important factor. In this study, we applied the WRF/Chem chemical transport model to examine the detailed large-scale 3D transport structure and photochemical O₃ formation processes targeting the period of July-August 2007. We found that the land-sea breeze circulation plays an important role when a high O₃ concentration was observed in the Tanzawa Mountains. We also showed the typical penetration direction of the high O₃ concentration air mass to Tanzawa Mountains based on the trajectory analysis.

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The Ministry of the Environment Japan launched a cohort study to investigate the health effects of fine particles. To validate the study, it is necessary to evaluate whether a concentration of particulate matter less than 2.5 μm in aerodynamic diameter (PM_2.5) at a monitoring site is representative of the personal exposure levels around the site. We selected a PM sampler suitable for this study, and then measured the PM_2.5 personal exposure levels of student volunteers and the concentration at a monitoring station in the study area as a preliminary study. The objectives of this study were confirming the feasibility of the PM_2.5 personal exposure measurement and making manuals for a field survey. The PM_2.5 concentration at the station was almost representative of personal exposures, and it was suggested that a PM_2.5 personal exposure survey could be conducted for the study subjects of the PM_2.5 epidemiological study. The relationship between the personal exposure level and the concentrations inside and outside residences which might be proxies of personal exposure were not very high.

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We have developed a mini open-top chamber system (mini-OTCs) to assess the effect of air pollutants, especially ozone, in combination with temperature stress on plants. The external dimensions of the chamber are 60 cm (W) x 85 cm (D) x 120 cm (H), while the exposure space is 60 cm (W) x 60 cm (D) x 120 cm (H). Honeycomb filters made of inorganic fiber paper incorporating a catalyst for removing any ambient O₃ were installed in the filtered air (CF) chambers, but those without a catalyst were installed in the non-filtered air (NF) chambers. Silicon rubber-coated belt heaters were used for preparing the temperature gradient. Experiments suggested that it had sufficient potential for assessing the effect of the ambient air quality on plant growth and/or yield in combination with the temperature gradient.

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