It is well know that polynuclear aromatic hydrocarbons (PAHs) including carcinogenic Benzo (a) pyrene are universal products caused by combustion of organic material, are environmental pollutants and many of them are known to be carcinogenic and mutagenic compounds. The Benzo (a) pyrene is a potential carcinogenic substance and has been monitored widely as an index of air pollution. For that reason, we have studied the simple and rapid analytical method of PAHs and applied the method to the determination of PAHs in air-borne particulate material and soil samples using by this methods. As a result, simple analytical method consisted of ultra sonic extraction and high performance liquid chromatography has been established for a routine analysis of the PAHs. The PAHs in airborne particulate material have been continuously investigating from November 1980 today. The concentration of pollutants decreases compared with those in 1980's. The percentage of the PM 2.5 out of PM 10 is mustly between 60-80%.

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The filter-pack method is generally used for the measurement of soluble ion components in aerosol, sulfur dioxide, nitric acid gas, hydrocloric acid gas, and ammonia gas in the air. In this study, the simultaneous measurement of nitrous acid gas using double alkaline impregnated filters of the filter-pack method is being considered for the first time. The filter pack contains five filters, i. e., a Teflon filter, a nylon filter, a firstalkalineimpregnated filter, a second alkaline-impregnated filter, and an acid-impregnated filter. In a laboratory experiment, it was found that artifact formation of nitrate and nitrite ions, representing below 1% of the concentration of nitrogen dioxides, occurs in the alkaline-impregnated filter. Thus, the interference on nitrogen dioxides can be estimated from the NO₂^- and NO₃^- content of the second alkaline-impregnated filter. This principle is similar to that of an annular denuder method. In addition, a parallel survey using the filter-pack method and the annular denuder method, which is generally used for the measurement of nitrous acid gas, was carried out in the field for three and half years beginning in October 2003. This was done in order to measure the weekly concentrations of nitrous acid gas in Sapporo. The results showed that nitrous acid concentrations obtained using the two methods were in good agreement because both concentrations were highly correlated (r=0.95); moreover the slope of the correlation curve was close to 1.0, and the intercept was shown to be small: i. e., y=1.09 x+2.28. Thus, it was concluded that the filter-pack method is useful for the monitoring of air pollutants including nitrous acid gas like an annular denuder method.

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We examined the contribution from emission sources in the Beijing and Shanghai areas for SO_x and NO_y concentrations using the Models-3 Community Multi-scale Air Quality modeling system (CMAQ) coupled with the Regional Atmospheric Modeling System (RAMS), in the first half of February, 1999, when a regional air pollution episode was observed in the Kyushu area. The CMAQ can reproduce the fundamental features of the temporal variations of observed SO_x (=SO₂+SO₄^2-) and T-NO₃^- (=HNO₃+NO₃^-) concentrations at Fukue Island and over the East China Sea. The model demonstrates that the heavy air pollutants in the Kyushu area from February 7 to 11 were transported from the East China region by a high pressure system over the East China Sea. At Fukue Island, the contribution of Shanghai emissions to surface concentration for both SO_x and NO_y reached its peak at 67%, and the averaged concentrations during the period of this episode were about 7 times higher than those from February 1 to 15. The contributions of Beijing and Shanghai emissions increased alternatively at intervals of about 1-4 days, due to the periodic variation of the airflow over East Asia. For the area-averaged SO_x and NO_y concentrations in western Japan, Beijing and Shanghai emission contribution is largest in the Chugoku and Kyushu areas, respectively. The total contribution of Beijing and Shanghai emissions was 18% for SO_x and 12% for NO_y in the western Japan from February 1 to 15. It has been concluded that the emissions for SO₂ and NO_x in the Beijing and Shanghai areas have a large impact on the air quality of western Japan.

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In FY 2002, which is the year with the highest frequency of Asian dust days identified in meteorological observatories in Japan, the attainment of air quality standards (AQS) for suspended particulate matter (SPM) was poor compared with attainment of AQS in recent years. We examined an interannual variation of the attainment of AQS and considered the effects of Asian dust episodes tothe attainment of AQS for the period FY 1992-2004.
The yearly attainment of AQS satisfies the following two standards:(1) 98-percentile value of the daily mean concentration is below the threshold (100μgm^-3), (2) high concentration exceeding the threshold never continues on subsequent days.
A remarkable Asian dust episode was widely observed in April 2002. The SPM concentration during the dust period was not so high (100-200μgm^-3) but the dust persisted for the 8-11 April period. As a result, this episode showed a reduction of approximately 40% in the attainment of AQS in FY 2002. By contrast, another dust episode, 21-22 March 2002, brought an extremely high concentration (>500 μgm^-3 in the highest polluted sites). The period of high concentration lasted about 30 hours. Therefore, the attainment/non-attainment area in FY 2001 depend on the beginning and end of the dust period whether it spreads over a border time (00 JST) for calculating daily mean values.
The number of high concentration days in a year is smaller in recent years than that in 1990s, particularly in late autumn and early winter. Owing to the reduction of high concentration days in a year, the low-level attainment of AQS in FY 2002 is substantially caused by the single dust episode observed during the 8-11 April period.

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Asian dust-storm (ADS) particles are significant as atmospheric particles during spring season in Japan. To investigate the characteristics of ADS particles and non-Asian dust-storm (non-ADS) particles, we collected atmospheric particles by low pressure andersen impacter in Kobe city in April and September 2003. We measured morphology and compositions by using field emission scanning electron microscopy (FE-SEM) coupled with an energy dispersive X-ray spectrometer (EDS). To estimate possible sources of the particles, all individual particles were divided into 6 groups according to their chemical compositions by cluster analysis.
The number of the soil particles in the size range of 0.47μm-7.65μm during ADS period was about two times high compared with that of the non-ADS counterpart. The max percentage of metal particles were 0.47μm-0.67μm in ADS period and 1.17μm-2.05μm in non-ADS period. 27% of 0.47μm-0.67μm particles were metal particles during ADS period. Spherical iron particles were observed on the surface of soil particles in ADS period.

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