We hypothesized that exposure to low-level outdoor and indoor air pollutants may affect the function of the neuro-immune-endocrine system dependent on the different genetic background, developmental stages, gender and occurrence of allergic diseases. To clarify the susceptibility to environmental chemicals, the present study was designed to summarize the inter-species variation in sensitivity to the expression of chemical-mediated neurtrophins, its related receptors and inflammatory mediators in the mouse and to present the combined effect of chemical exposure and allergic challenge on neuroimmune-related markers in sensitive mouse strain.

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To evaluate the air quality of a suburban area of Tokyo, the long-term measurement of volatile organic compounds (VOCs, 58 species) was conducted at Hachioji, Tokyo, Japan. The measurements were carried out from May 2002 to December 2008. Canister samples were taken once a week and analyzed using a gas chromatograph equipped with a flame ionization detector. Though the benzene concentration showed a decreasing trend during the past 7 years, no defined trend was found for the other VOCs. Most of the VOCs did not show any clear seasonal variation, but some VOCs from biogenic activity and fuel evaporation showed seasonal variations with higher concentrations during the summer. The OH reactivity (k_OH) and ozone formation potential (OFP) were deduced from the observed VOC concentrations. When comparing the VOC concentrations, k_OH, the OFP for each season, the dominant VOCs were different. Also, the contribution of alkane, alkene, aromatics and biogenic VOCs are different for the VOC concentrations, k_OH, OFP. It is important to use a suitable index in order to diagnose the air quality.

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The prediction of the response of a river basin to climate change requires an integrated approach consisting of regional modeling of the atmosphere and hydrology. The atmosphere is linked to the land surface by precipitation and evapotranspiration. At the regional basin scale, the spatial variability of precipitation is crucial for accurate prediction of runoff and overall hydrologic cycle. In this paper, the high-resolution mesoscale precipitation in Yodo River basin of Japan was produced by WRF (Weather Research and Forecasting) mesoscale meteorological model. Nesting of high-resolution mesh inside a coarse mesh produced downscaled precipitation data with 3-km grid size. The 3-km grid data was further downscaled to 1-km grid data according to the terrain structure. The spatial and temporal features of this precipitation data were validated with Radar GPV (Grid Point Value) data and observed station data.

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In this study, the spatial distribution of ozone concentrations in Hyogo Prefecture in 2008 using a numerical analysis technique (MM5/CMAQ system) was investigated in order to estimate them in areas without monitoring stations. As a result, the ozone concentrations increased in the order of May > September > July > December. These results were in good agreement with the monitoring data. The monthly mean ozone concentrations in both May and July in Hyogo Prefecture were affected by the transboundary air pollution from overseas which is estimated to be 10ppb or higher. In May, the air mass flowed from the Sea of Japan to all over the Hyogo region, and it was found that the spatial distribution of the O₃ concentrations was determined by the titration of ozone with locally emitted NO_X (NO). In July, it was found that the spatial distribution of the O₃ concentrations was affected by the O₃ generation from local emission sources along the trajectories of the air masses as well as the transboundary air pollution from overseas.

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Various regulations concerning anthropogenic emission sources have been enforced in recent years in Japan. The long-term trend and interannual variations of suspended particulate matter (SPM) concentrations from FY 1991 to FY 2006 in Japan were investigated using monthly data observed at air quality monitoring stations. SPM concentrations in both the winter and summer decreased during this period. Most of monitoring stations showed decreasing trends in the winter since both the stationary and mobile emission controls are effective for the SPM reduction. No clear trend was seen in the spring, because the contribution of artificial sources to the SPM was smaller than that in the other seasons.
The interannual variations in the SPM concentration were found to be synchronous in the large areas of Japan. The composite analysis of the pressure pattern and wind system indicates that high/low concentration years of the SPM correspond to the weak/strong northwest monsoon in winter. In the summer, anticyclonic circulation over Japan leads for a high SPM concentration, on the contrary, a low pressure zone over Japan or a southeasterly wind system produces a low SPM concentration.

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A flow-type generation system based on the reaction of a sodium nitrite solution with sulfuric acid has been developed for the parts per billion levels of gaseous nitrous acid. The reagent solutions are continuously nebulized by an incoming large volume flow rate of air in a tee tube and the resulting air/droplet mist is carried down into a porous polytetrafluoroetylene (PTFE) tube. The porous PTFE tube wall virtually blocks the passage of droplets but offers little resistance to the existing gas flow.
There are good correlations between the gaseous nitrous acid and the sodium nitrite concentration or pumping rate of the reagent solutions. With an increasing air flow rate, the gaseous nitrous acid concentration decreased while the purity increased. The amounts of NO and NO₂ are very small compared to that of the gaseous nitrous acid (about 5% and 2%, respectively). The gaseous nitrous acid concentration is almost constant at the sulfuric acid concentration above 10 mM for 3 mM sodium nitrite.

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The impact of anthropogenic aerosols transported from East Asia on the summertime PM_2.5 mass concentration in Japan was investigated, based on the results of intensive observations of airborne particulate matter from August 4 - 9, 2007, in Osaka. The mass concentration of PM_2.5 was monitored by a β-ray absorption-based continuous monitor without any moisture control. The level of the PM_2.5 mass concentration changed by 20-30 μg/m³ between the first and the second half periods, though the primary and secondary contributions from the nearest sources did not significantly change throughout the observations. The effect of the anthropogenic aerosols from East Asia was considered to be the major factor affecting the difference in the PM_2.5 levels between the periods. Due to the effect of the East Asian aerosols, the mass concentrations of PM_2.5 increased along with the water vapor concentration, seemingly because of the high hygroscopic constituents (i.e., ammonium sulfate). This kind of moisture dependence was not observed when the air masses were from the Pacific Ocean. East Asian anthropogenic aerosols directly affected the PM_2.5 mass concentration by increasing the background levels, and indirectly by its more hygroscopic nature, when monitored by instruments without moisture control.

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