The Land Use Regression (LUR) model is now used for exposure assessment in air pollution epidemiologic studies rather than measuring/monitoring pollutants. However, there have been few epidemiologic studies using the LUR models and characteristics of the model have been unclear in Japan. To determine whether the LUR model can be applicable to air pollution epidemiologic studies as the method of exposure assessment in Japan, we developed the LUR models for NO₂, NO_x, and SPM in Yokohama.

The annual means of NO_x, NO₂ or SPM measured at 29 monitoring stations in Yokohama city in 2005 were regressed on land use data such as residential/industrial area, traffic volume, etc, using a manual stepwise method. The adjusted R² values for the NO_x and NO₂ regressions were 0.88 and 0.81, respectively. The adjusted R² for the SPM regression was 0.55. The distributions of the concentrations were mapped using Arc-GIS software. The LUR models we developed and the concentration maps may be valid compared to other models and the LUR models developed in the western countries. However, a much higher resolution for the concentration distribution based on the LUR models might be necessary for epidemiological studies of traffic-related air pollution in Japan. We should be necessary to consider the measurement points, etc, necessary for developing the LUR models.

Various desert and semi-arid areas in Northeast Asia that are susceptible to sandstorms and the generation of kosa aerosols have been investigated over a ten-year period commencing in 1998. Sixty-four samples of surface soils were collected from eight regions in the Taklamakan, Gobi deserts, the Hung tu (Chinese Loess) Plateau, and others. The grainy soil particulates (<100 μm) and the fine soil particulates (<10 μm) were classified by the sieve/cascade-impactor methods, and the chemical compositions of the particulates were determined. The darkest yellow-red colored samples were a group of surface soil samples from the Eastern Gobi region, and it was found that the CO₃-C, Ca and Mg contents were significantly less than those from the other areas. It was postulated that there was an underdeveloped formation/accumulation process of calcite mineralization in the surface soil layer of the Eastern Gobi. The concentration ratios of Ca, Mg, Sr and P to Al exhibited relatively large variations (15–52 RSD%), whereas the ratios, with respect to Al, for K, Ti, and Ba were significantly lower (7–9 RSD%). A cluster analysis based on the elemental ratios (with respect to Al) for Ca, Mg, Sr and P was used to identify the sources of the kosa aerosols which were transported to Japan (16 events studied). The estimated source regions of the kosa aerosols were substantiated using observational regions based on the SYNOP network reports about dust storms.

We assessed the ambient air pollution based on the ozone (O₃) impacts on the growth of radish (Rahapnus sativus L. cv. Comet) using the open-top chamber method in Nagasaki city, which faces transboundary air pollution such as tropospheric O₃. There were two treatments in the present study: ozone-removal filtered air (FA) and non-filtered air (NF) treatments. A one-week exposure experiment was conducted nine times in Nagasaki University (Nagasaki, Japan) from March to October 2015. The below-ground dry mass of radish grown in the NF treatment was significantly lower than that in FA treatment in the experiments in mid-May, September and October. There was no significant relationship between the mean O₃ concentration and relative value of the root dry mass in the NF treatment to that in the FA treatment. On the other hand, the reduction rate in the below-ground dry mass per unit O₃ concentration became greater with the increasing mean air temperature and relative air humidity. These results indicate that, depending on the climatic conditions, the O₃ concentrations observed in Nagasaki in the spring and autumn were high enough to reduce the growth of O₃-sensitive plants, such as radish.

Source apportionments of PM_2.5 in central Kumamoto during the winter of 2014 were evaluated based on the air quality model (CMAQ) by applying the zero-out approach. The largest source sensitivity was estimated to abroad emissions with 70% relative percentage due to the trans-boundary air pollution from East Asia during the study period, and the second largest source was the Kumamoto emissions of 20%. For nitrate and ammonium, Kumamoto dominated with 80% and 40%, respectively. From the detailed analysis of the Kumamoto emissions involving combustion, automobile, agriculture and livestock sources, the nitrate and ammonium were associated with agriculture and livestock in Kumamoto (Agri.[Ku]). A nonlinear response of nitrate was found in the emission reduction range between of 20–50%. A sensitivity analysis suggested that reduction of the Agri.[Ku] emission caused a decrease in the particulate and gaseous ammonium, and caused a decrease in the particulate nitrate and increase in nitric acid (HNO₃). These results and backward trajectory suggested that the long-range transported HNO₃ from East Asia reacted with locally emitted ammonia in central Kumamoto, and formed particulate ammonium nitrate. The results indicated that observation of HNO₃ is important for promoting our understanding of the PM_2.5 sources during the winter in Kumamoto.