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Total suspended particulate matter (TSP) was collected during the summer and winter in five Japanese cities spanning Hokkaido to Kyushu (Sapporo, Kanazawa, Tokyo, Sagamihara and Kitakyushu) from 1997 to 2014. Nine polycyclic aromatic hydrocarbons (PAHs) with four to six rings, including pyrene (Pyr) and benzo[a]pyrene (BaP), were identified using high-performance liquid chromatography (HPLC) with fluorescence detection. Two nitropolycyclic aromatic hydrocarbons (NPAHs), 1-nitropyrene (1-NP) and 6-nitrobenzo[a]pyrene (6-NBaP), were identified by HPLC with chemiluminescence detection. A comparison of PAH and NPAH concentrations and [NPAH]/[PAH] ratios such as [1-NP]/[Pyr] and [6-NBaP]/[BaP] revealed the following characteristics in the five cities: (1) In Sapporo, Kanazawa, Tokyo and Sagamihara, the concentrations of PAHs and NPAHs were high at the beginning of the sampling period and then steadily decreased, with NPAHs decreasing faster than PAHs. The large initial [1-NP]/[Pyr] ratios suggest that the major contributor was automobiles but subsequent decreases in this ratio suggest decreased automobile contributions. (2) By contrast, PAH concentrations in Kitakyushu did not decrease during the sampling period, though concentrations of NPAHs decreased. The consistently smaller [1-NP]/[Pyr] ratio and larger [6-NBaP]/[BaP] ratio in Kitakyushu suggests that the major contributor of PAHs was not automobiles but iron manufacturing which uses a large amount of coal. The sudden increase in atmospheric PAH concentrations in the winter of 2014 may also be due to iron manufacturing.

Airborne particulates were collected in seven cities in the Pan–Japan Sea countries, Shenyang (China), Vladivostok (Russia), Seoul (South Korea), Kitakyushu, Kanazawa, Tokyo and Sapporo (Japan), in winter and summer from 1997 to 2002. In addition, particulates from domestic coal-burning heaters and diesel engine automobiles were collected in Shenyang and Kanazawa, respectively. Nine polycyclic aromatic hydrocarbons (PAHs) and four nitropolycyclic aromatic hydrocarbons (NPAHs) in the extracts from the particulates were analysed by HPLC with fluorescence and chemiluminescence detections, respectively. The PAHs were fluoranthene, pyrene (Pyr), benz[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, benzo[ghi]perylene and indeno[1,2,3-cd]pyrene, and NPAHs were 1,3-, 1,6-, 1,8-dinitropyrenes, and 1-nitropyrene (1-NP). Mean atmospheric concentrations of PAHs in Shenyang and Vladivostok were substantially higher than those in Seoul, Tokyo, Sapporo, Kitakyushu and Kanazawa. However, the mean atmospheric concentrations of NPAHs were at the same levels in all cities except Kitakyushu. The expected seasonal variations (greater PAH and NPAH concentrations in winter than in summer) were observed in all cities. In order to study the major contributors of atmospheric PAHs and NPAHs, both cluster analysis and factor analysis were used and three large clusters were identified. Furthermore, the concentration ratios of 1-NP to Pyr were significantly smaller in Shenyang, Vladivostok and Kitakyushu and the values were close to those observed in particulates from coal stove exhaust. By contrast, in Seoul, Kanazawa, Tokyo and Sapporo the [1-NP]/[Pyr] ratio reached values similar to those of particulates released from diesel-engine automobiles. The [1-NP]/[Pyr] concentration ratio seemed to be a suitable indicator of the contribution made by diesel-engine vehicles and coal combustion to urban air particulates.

In this study, airborne particulates were collected at three sites, two in a downtown area and the other in a suburban area of Kanazawa, Japan in each season for 7 years. Two polycyclic aromatic hydrocarbons (PAHs), pyrene (Py) and benzo[a]pyrene (BaP) and four nitropolycyclic aromatic hydrocarbons (NPAHs), 1-nitropyrene (NP) and 1,3-, 1,6-, and 1,8-dinitropyrenes (DNP) were determined by high-performance liquid chromatography with fluorescence and chemiluminescence detection. At the downtown sites, the mean concentration of each DNP was about two orders of magnitude lower than that of 1-NP and more than three orders of magnitude lower than those of Py and BaP. This tendency reflected the composition of PAHs and NPAHs in diesel-engine exhaust particulates. Concentrations of these PAHs and NPAHs were higher at the downtown sites than at the suburban site, suggesting the dilution of these compounds during the transportation from the downtown to the suburban area. The concentration ratios of NPAHs to PAHs were larger at the downtown sites than at the suburban site. Studies using UV light and sunlight showed that degradation of NPAHs was faster than that of PAHs. Thus, the lower concentrations of NPAHs in the suburban sites may be due to their being photodegraded faster than PAHs during the atmospheric transportation from the downtown area to the suburban area.

Airborne particulates were collected at a site near a group of factories in Kitakyushu, one of the most industrialized cities in Japan, and at downtown sites in Sapporo and Tokyo, typical large commercial cities. We determined the levels of polycyclic aromatic hydrocarbons (PAHs) and nitropolycyclic aromatic hydrocarbons (NPAHs), which are known to be carcinogenic and/or mutagenic. The atmospheric concentrations of most PAHs with 4-, 5-, and 6-rings were higher in Kitakyushu and Tokyo than in Sapporo. On the other hand, atmospheric concentrations of the strongly mutagenic NPAHs were the highest in Sapporo, intermediate in Tokyo, and lowest in Kitakyushu. The atmospheric concentrations of 1-nitropyrene (1-NP) in Kitakyushu were one order of magnitude lower than those in the two commercial cities. Therefore the concentration ratios of NPAHs to their nucleus PAHs were significantly smaller in Kitakyushu than in the two commercial cities. This result suggested that the atmospheric levels of NPAHs in Kitakyushu were comparatively low, although the air in Kitakyushu was as heavily polluted with PAHs as the air in Tokyo. The concentration ratio of dinitropyrenes (DNPs) to 1-NP in Kitakyushu was much higher than that in the other two cities. A possible reason for the above two differences between the two types of cities is the contribution of chimney exhaust of steel manufacturing plants in Kitakyushu, which contains high concentrations of PAHs.

Airborne particulates were collected during the same periods in downtown Kanazawa, Sapporo and Tokyo and polycyclic aromatic hydrocarbons (PAHs) and nitropolycyclic aromatic hydrocarbons (NPAHs) were determined together with several heavy metal elements and water-soluble inorganic ions. The mean concentrations of metal elements and inorganic ions were the highest in Tokyo, followed by Sapporo and the lowest in Kanazawa both in winter and summer, and were strongly dependent on the amount of airborne particulates. These tendencies were different from the cases of PAHs and NPAHs. Correlations between the organic compounds (PAHs and NPAHs) and several inorganic pollutants were strong only in winter samples of Sapporo, but not so strong in Kanazawa and Tokyo. Because PAHs and NPAHs and several combustion-origin inorganic substances are, in general, detected mainly in the fine airborne particulates, it was reasonable that the significant correlations were found only in the winter samples of Sapporo where the generation of the coarse and crustal particulates were suppressed by snow or ice. Though the atmospheric concentrations of PAHs and NPAHs in Kanazawa were much lower than in Sapporo, the correlation among the NPAH compounds and between PAHs and NPAHs were surprisingly similar in these two cities. The strong correlations indicated that the atmospheric behaviors of the PAHs and NPAHs studied were similar in the two cities and that the source of PAHs and NPAHs might be the same. On the contrary, strong correlations were not observed in Tokyo, suggesting the possibility of multiple sources or formations/degradations of PAHs and

Diesel-engine exhaust and airborne particulates were collected in downtown and suburban areas and five mutagenic nitroarenes (2-nitrofluoranthene (NF), 1-, 2- and 4-nitropyrenes (NPs) and 6-nitrochrysene (NC) in benzene-ethanol extracts were determined by high-performance liquid chromatography with chemiluminescence detection. 1- and 4-NPs and 6-NC were found in diesel-engine exhaust particulates, however, 2-NF and 2-NP were not detected. On the other hand, all five nitroarenes were found in airborne particulates. Diurnal concentration patterns of 4-NP and 6-NC in the downtown area were similar to the pattern of 1-NP, but the patterns of 2-NF and 2-NP were different from the pattern of 1-NP. These results strongly suggested that 2-NF and 2-NP are formed in the atmosphere. Of the five nitroarenes, 2-NF had the largest suburban / downtown concentration ratio. 2- and 4-NPs and 6-NC all showed larger ratios than did 1-NP. These results showed that 2-NF and 2-NP were formed in the atmosphere, but that the secondary formation of 4-NP and 6-NC were not known. Taking mutagenic activity and the atmospheric concentration into consideration, the mutagenic contribution of 2-NF was estimated to be comparable with that of 1-NP in the downtown area, and more than that of 1-NP in the suburban area. This result suggested that the mutagenic contribution of the minor nitroarenes formed in urban air might not be negligible.

Air samples were collected at suburban Kanazawa and concentrations of dioxins in both gaseous and particulate phases were determined separately. The concentrations of the gaseous phase of dioxins increased with increasing temperature. Co-planar polychlorinated biphenyls (co-PCBs), whose vapor pressures are higher than those of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), were mainly in the gaseous phase samples in all the seasons. The gaseous phase ratios [gaseous phase/(gaseous phase + particulate phase)] of tetrachloro dibenzo-p-dioxins and dibenzofurans (TeCDD/DFs) were high regardless of the temperature. However, the gaseous phase ratios of penta-hepta CDD/DFs varied widely depending on the temperature. Gas/particle partitioning of atmospheric dioxins depended on not only the number of chlorine-substitutions but also the positions of the chlorine-substitutions. The position of chlorine-substitution in an isomer affects the isomer's molecular polarity. Dioxin isomers with higher molecular polarity, which have shorter retention times on the selected ion monitoring (SIM) chromatograms of their homologues, tended to be distributed unevenly in the gaseous phase. In addition, the differences in the gaseous phase ratios between the isomers with higher molecular polarity and those with lower molecular polarity increased with decreasing temperature.

Air samples were collected at the sides of busy traffic roads in downtown Kanazawa, Sapporo and Tokyo during the same periods both in the daytime and in the night, in winter and summer. We determined the levels of polycyclic aromatic hydrocarbons (PAHs) and nitropolycyclic aromatic hydrocarbons (NPAHs), which are known to be carcinogenic and/or mutagenic. PAHs and NPAHs were analyzed simultaneously with an HPLC system with fluorescence detection for PAHs and another HPLC system with chemiluminescence detection for NPAHs, respectively. The amounts of airborne particulates were larger in the daytime than in the night in all three cities. This result was thought to reflect the diurnal change of such urban activities as traffic volume. Many of the PAH and NPAH compounds showed higher concentrations in the daytime than in the night, and also showed higher concentrations in winter than in summer in the three cities. This result coincided with the trends observed in our continuous surveys in downtown Kanazawa for several years. However, 5-ring PAHs, such as benzo [a] pyrene, and dinitropyrenes in Tokyo did not show such diurnal or seasonal differences. The composition ratio of NPAHs and the contribution of diesel-engine vehicles to the atmospheric concentrations of NPAHs were calculated from all the data of this survey. The concentration ratio of dinitropyrenes to 1-nitropyrene became larger with an increase in the ratio of diesel-engine vehicles to the total vehicles registered, suggesting a large contribution of diesel-engine vehicles to the concentrations of these NPAHs in urban air.

Polycyclic aromatic hydrocarbons (PAH) and nitropolycyclic aromatic hydrocarbons (NPAH) in airborne particulates collected simultaneously at downtown and suburban sites and in exhaust particulates from diesel and gasoline engine vehicles were determined. The mean concentrations of all compounds in the atmosphere were lower at the suburban site. The differences between the two sites were smaller in airborne particulates than in the atmosphere. However, the difference in NPAH concentrations in particulates between the two sites was greater than the difference in PAH concentrations, suggesting that the NPAH were less stable than the PAH. The concentrations of 1-nitropyrene and 1,3-, 1,6- and 1,8-dinitropyrenes were generally much higher in automobile exhaust particulates than in airborne particulates because the former were collected directly. However, 2-nitrofluoranthene and 2-nitropyrene were observed in airborne particulates but not in automobile exhaust particulates. The diurnal concentrations s...