An award of the Japan Society of Atmospheric Environment was recently obtained, and the following various fields related to atmospheric chemistry were subjects, i.e., developments of new methods and measurements of trace amounts of gaseous substances, reactions that must occur in the environment, reactions during freezing or thawing of water droplets in the environment, human health damage by HONO, and measurements of pollutants in exhaust gas from engine using biodiesel fuel and their effects on atmospheric chemistry. It is difficult to describe all these results in the limited space here, therefore, some results related to HONO, such as, 1) multi-phase chemistry in the atmosphere, 2) measurement of gaseous HONO, and 3) human effect of HONO are described.

This paper described the findings obtained from the numerical analyses of atmospheric chemical and physical phenomena using meteorology and air quality models. An estimate of the amount of acid deposition by fog water deposition revealed that the contribution of fog to the acid deposition was comparable to that of precipitation in some mountainous areas in the Kinki Region of Japan. In the Urban air quality Model Inter-Comparison Study (UMICS) to improve the model performance for simulating fine particulate matter (PM_2.5) in the Greater Tokyo Area of Japan, various sensitivity analyses revealed pathways for improvement of the underestimate of particulate nitrate and the overestimate of organic aerosols. Additional numerical analyses also showed numerous findings about the long-range transport and source contribution of PM_2.5 and ozone.

The atmospheric fine particulate matter (PM_2.5) is one of the main air pollutants and there have been numerous investigations involving chemical composition analyses and concentration measurements of the atmosphere. However, it would be not enough to understand the chemical compositions and sources of PM_2.5. This paper reviews recent research and trend for levoglucosan measurement in PM_2.5 as a tracer from biomass burning, and summarizes the results of the chemical transformation in atmospheric processes.

Investigation of the characteristics of particulate matter suspended in a subway station platform was carried out using multiple monitoring instruments such as CPC, SMPS, APS, OPC, K-MACS (Keio-Measurement system for Aerosol Charging State), portable PM_2.5 monitor, FE-SEM/EDX, and EDXRF. The PM_2.5 concentrations in the subway station increased during the morning rush hour, then gradually decreased. It varied in the range of 50–120 μg/m³ showing a constant up-down pattern along with the arrival of a train in the afternoon. The PM_2.5 concentrations in the subway station were approximately 2–5 times higher than those outside. In particular, particles larger than 0.5 μm were higher than those found outside. The concentrations of particulate metals such as Fe, Ti, Cr, Mn, Cu, and Zn in a subway station were several ten to hundred times higher than those outside. On the other hand, there was no significant difference in the particulate S concentrations between the subway station and the outside site. More than 70% of the particles in the subway station carried a certain amount of electric charges.