In Tokyo, air pollution due to exhaust gases from automobiles became a serious problem in the late 1980s. This was caused by an increase in the amount of emissions resulting from the rapid increase in diesel vehicles, which gained popularity after the 1973 oil crisis.
Therefore, by considering heavy-duty diesel vehicles in use, we studied the emission characteristics and methods for their reduction. A legal test mode and an actual running mode were compared. Since the engine speed and engine load constantly change in the actual running condition, the effects of exhaust-gas regulation during the steady test mode were different from those in actual running condition. Therefore, we proposed that the regulation technique should be adapted to the actual running condition. We developed an on-board type measurement system, and conducted a running survey of the arterial road in Tokyo, and clarified the NOx emission mechanisms for each running modes (idling, acceleration, cruising and deceleration). For example, idling was a major contributor to emissions in congested traffic, while acceleration was a major contributor to emissions when driving on arterial roads. Then, we proposed “idle stop” as a methods to reduce air pollution which a user can grapple, and demonstrated a reduction in the amount of NOx emissions and fuel consumption. Next, we conducted research on a diesel particulate filter (DPF) for heavy-duty diesel vehicles in use and obtained the following results. When the type of vehicle and running conditions are specified, a retrofit DPF is effective in reducing not only PM but also HAPS.
Although the air pollution situation in Tokyo is improving, non-regulated substances, such as PM 2.5 and HAPS are yet to be examined. Moreover, it is necessary to provide after-treatment equipment in future diesel vehicles. Therefore, for exhaust-pipe emissions, not only their regulation but also means for reducing health effects are required.

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Continuous monitoring was performed to characterize temporal variations of size-segregated sulfate and nitrate particles with high time resolution at Uji during the springtime (April 1 to May 12, 2005) including Kosa events. Simultaneous measurements were also carried out for gaseous components (NO₃, SO₂, O₃), PM_2.5 BC, particle number concentration and some meteorological parameters. Nitrate and sulfate concentrations were measured by the R & P Model 8400N equipped with PM 1 and PM 10 inlets and 8400S with similar inlets, respectively. The time series of the size-segregated sulfate and nitrate measurements were analyzed in the frequency space with the corresponding power spectra. Significant peaks were found in the power spectra at the frequencies of 1 and 1/ 3.5 per day for nitrate (both fine and coarse) and of 1/ 2.7 per day for coarse sulfate. The average diurnal variation of the 1-hour-averaged nitrate concentration in fine particles showed a distinct peak around 8 a. m. and quite a similar pattern was obtained for NO₃ and BC. This result indicates that traffic contributes the diurnal periodicity in the spectrum. The comparison between the inverse of the band-pass filtered power spectrum and the time series of particle number concentration suggested that the 3.5 day periodicity for coarse nitrate may be attributed to the modified components of Kosa particles.

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A non-extractive laser based continuous analyzer for HCl (laser analyzer) was compared with an ion electrodebased continuous analyzer for HCl (ion electrode analyzer) at municipal waste incinerators. A laser analyzer monitors concentrations of HCl in wet gas and responds well to short-term changes in concentration. An ion electrode analyzer monitors concentrations of HCl in dry gas that are averaged over a short time and have some time lag.
There was good correlation between concentrations of HCl in dry gas, calculated from values measured with a laser analyzer and water content of the flue, and values measured with an ion electrode analyzer. It was clear that a laser analyzer was a practical monitor for concentrations of HCl in wet gas and a laser analyzer could be used to report HCl in dry gas for self-management at municipal waste incinerators by calculation from HCl values measured and mean water content measured beforehand.

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In order to assess the spatial distribution of wet deposition, a regionalization of the time-series model was considered through the application of a geostatistical method. Datasets employed were obtained from nation-wide monitoring measurements of nss-sulfate deposition by Ministry of the Environment and the Japan Environmental Laboratories Association. The spatiotemporal distribution of nss-sulfate deposition was modeled as a joint realization of a collection of spatially correlated time series. Parametric temporal trend models were first established for individual monitoring stations, and the obtained model parameters and residuals were regionalized in space. Stochastic simulation and kriging were performed in order to formulate predictions of the trend models and the residual profiles for the spatial locations and time instants with out the monitoring measurements. The independently regionalized trend and the residual realizations were added together to produce realizations of nsssulfate deposition and to map the distribution. The results of the analysis suggest that nss-sulfate deposition has a trend that typically decreases throughout the nation. Areas with high deposition were found to indicate significant variations in regional features of the map of the final realization. In summer, relatively high deposition of nss-sulfate were realized in the Kyushu region and near the Seto Inland Sea. In winter, on the other hand, the nss-sulfate deposition was highly elevated on the coast of the Sea of Japan. An application of the present method to the wet deposition dataset for the Kanto area enabled us to make a good estimate for the increase in the nss-sulfate deposition, which could be ascribed to volcanic emissions from Miyakejima.

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The aqueous film-forming foams (AFFFs) are used for massive conflagration such as industrial fire and petroleum fire because of their efficient fire control. In this study, in order to analyze the combustion products of them, the flow type reactor was designed and combustion experiment carried out. Chemicals were extracted from generated powder dust to distillated water by ultrasound and analyzed by using LC-MS. And combustion product gases were trapped by tedler-bag and analyzed by using GC-MS. Perfluorooctane sulfonate and perfluorooctane acid were detected form powder dust, and other polycyclic aromatics were also detected. Hydrogen fluoride and sulfur dioxide were detected from combustion product gas. In case of combustion of the fluorochemical surfactants, perfluorooctane sulfonate, perfluorooctane acid, hydrogen fluoride and sulfur dioxide were also detected. Therefore, there is the possibility of generating perfluorooctane sulfonate (C₈HF₁₇SO₃) and perfluorooctane acid (C₈HF₁₅O₂) from fluorochemical surfactants in the AFFFs. Perfluorooctane sulfonate and perfluorooctane acid have been used all over the world, mainly as water repellent agents, fluorochemical surfactants, coating agents etc. However they are environmental contaminants because of their stability, bio-accumulativeness, and long-term persistence in the ecological environment. At the present day, they are diffused all over the world (PFOS problem). Fluorochemical surfactants are key compounds in the aqueousfilm-forming foam (AFFF) formulations. The combustion of AFFFs may become cause of PFOS problem.

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The benzene concentrations at background site and at roadside sites in Okinawa Prefecture were investigated by canister-GC/ MS analysis from April 2004 to March 2005. The results were as follows. 1) The benzene concentrations at the background site tended to be lower in summer than in any other season. By using backward trajectory analysis, it was found that inflows of air masses from the Pacific Ocean to Okinawa Island were seen in low benzene concentration cases, and inflows of polluted air masses from the continental side were seen in high benzene concentration cases. The annual average concentration of benzene at the background site in Okinawa Island was 0.44μg/m³. 2) The benzene concentration at roadside sites tended to be lower when the wind blew strong. The annual concentration of benzene obtained by continuous measurement was estimated by using the relationship formula between the observed benzene concentration and the wind velocity. Its annual average concentration was estimated to be approximately 20-30 percent lower than the annual average concentration calculated from 12 samples which were gathered over a 24 hour period once per month. 3) The annual cancer risk to the population associated with ambient benzene was estimated to be approximately O.24 annual cases per 1.35 million people living in Okinawa Prefecture.

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