Ozone impact on the forest in the Tanzawa Mountains has been recognized for many years. In order to understand the forest decline, the hourly stomatal O₃ flux and the accumulated Phytotoxic Ozone Dose (POD_y: y means a threshold) were estimated using two numerical models. The numerical models (meteorological model: MM5 and air quality model: CMAQ) were executed to estimate the hourly O₃ concentration and the meteorological elements (air temperature, specific humidity, insolation and wind speed) from April to October including the leafing time to the leaf-fall time. We compared the POD₁（ 26.2 mmol/m² ）based on observation and the POD₁ ( 27.7 mmol/m² ) based on the output of numerical models at the Inukoeji station in the Tanzawa Mountains, and these POD₁ values were comparable. It shows the possibility of an application of numerical models for an O₃ impact study in the Tanzawa Mountains. The horizontal distribution of the POD₁ showed that the POD₁ exceeded the critical level in the Tanzawa Mountains. The POD₁ depends on the altitude and reaches higher values at the top of the mountains, because the stomatal O₃ conductance parameters on temperature and humidity depend on the altitude and are higher values on top of the mountains.

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The generation of polycyclic aromatic hydrocarbons (PAHs) by thermal cooking was evaluated depending on the main components of foods, i.e., carbohydrate, protein and fat contents. Seven foods were tested for grilling and the cooking exhaust was collected. Then the PAHs in the exhaust gas were analyzed. The concentrations of particulate PAHs in the cooking exhaust of low-fat foods such as scampi, sasami chicken and corn were lower, whereas much higher concentrations of PAHs were observed in the cooking exhaust of rich-fat foods such as rainbow trout and pork. Phenanthrene, fluoranthene and pyrene were the dominant components of PAHs, accounting for 53 to 62% to the total PAHs, regardless of food types. The concentration of PAHs in the cooking exhaust was positively correlated to the amount of fat in the food, however not with the amount of carbohydrates and protein. From the results above, it was indicated that the concentration of PAHs in the cooking exhaust was estimated by the amount of fat in the food, regardless of food type. Furthermore, the behavior of PAHs generated by pork grilling was evaluated, showing that only 0.02% of the PAHs generated were estimated to be residual in the food. Almost all of the PAHs generated were transferred to the gas phase and 53% of those were emitted to the outdoors while 47% were removed by the ventilating fan filter.

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An improved analytical method for the determination of total and hexavalent chromium in air has been developed to meet the requirement of revision of substances requiring priority action in Japan. Total Cr was measured using energy dispersive X-ray fluorescence spectrometry, and hexavalent chromium was measured by alkali digestion followed by ion chromatography coupled with postcolumn diphenylcarbazide absorption spectrophotometry. A trace amount of hexavalent chromium was always found in the extraction solution, and sodium hydroxide was a possible contamination source. The recovery of hexavalent chromium through the analytical procedure developed in this study was almost 100%. Changes in the chemical form of chromium, Cr^VI to Cr^III or vice versa, were not observed during 1 week of air sampling. The concentrations of total Cr were 6.5±4.9 ng/m³, those of Cr^VI were 1.0±1.0 ng-Cr^VI/m³, and the ratios of Cr^VI to total Cr were 17.4±15.1%, in PM_2.5 collected in Yokohama, Japan, from January, 2012 to July, 2013 (n=14).

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Both GEOS Chem chemical transport model and REAS emission inventory were used to analyze ten-years (2004–2013) of aerosol variation including PM_2.5 over East Asia. A remarkably high PM_2.5 concentration over central east China (CEC) in January 2013 was well simulated. We found that this heavy pollution occurred within the stable atmospheric condition due to the exceptionally weak Siberia high-pressure intensity (SHI), and pollutants were mainly trapped below the shallow PBL (< 1 km) over the CEC region. Comparison of the surface level black carbon (BC) concentration between 2012 and 2013 under fixed emission conditions shows that the BC level over the CEC in 2013 was about 30% higher than that in 2012. We also found that even if the concentration level over CEC is very high, the amount of horizontal transport flux in the region from CEC to Japan and the number of high pollution cases exceeding the threshold level did not correlate to the concentration of CEC region. The IPCC AR4 global model future prediction suggested that the SHI decreases due to global warming, and this indicated that the frequency of very high air pollution over the CEC might increase in the future if significant emission regulations over China are not conducted.

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