Particulate matters whose diameter is under 10 μm are usually suspended in air and are called suspended particulate matter (SPM) in Japan. SPM is a complex mixture of size and types from many kinds of sources. SPM and NO₂ are those of air pollution which shows no signs of improvement at all in the urban area in Japan. The concentrations of SPM and NO₂ often exceed environmental ambient air quality standard at all stations in urban area particularly in early winter.

Taking effective action against this pollution requires the development of a numerical model that can analyze the mechanism to generate high-concentration. Using simulation we can investigate which sources should be reduced for effective pollution control and probability for the residents to be exposed from SPM.

NIRE is developing a model which includes transport, reaction, and deposition processes and uses a meso to regional scale (100-1000 km) to reduce uncertainty in both chemical and physical process in the winter SPM and NO₂ pollution. This model is gradually making it possible to perform assessments of SPM by its chemical components, such as ammonium chloride (NH₄Cl) and ammonium nitrate (NH₄NO₃).

The concentration of atmospheric carbon dioxide has risen sharply since the Industrial Revolution, which leaves no doubt that this increase is due to the combustion of fossil fuels, but predictions of the concentration in the future are merely tentative because we lack knowledge about factors such as the absorption mechanisms of terrestrial ecosystems and oceans.

The global chemical transport model (CTM) can determine the atmospheric CO₂ concentration from the strength of sources and sinks between the land or sea and atmosphere. Using this relationship in reverse makes it possible to approximate the distributions of sources and sinks based on atmospheric concentration. At right is an example of concentrations in the lower atmosphere calculated from source/sink distributions found in this manner. The figure shows the northern hemisphere at a certain point in time during winter. Conducting such analyses will allow scientists to quantitatively assess the absorption mechanisms of terrestrial ecosystems and oceans, which will be useful in future predictions.

Life cycle assessment (LCA) is a technique for assessing the environmental aspects and potential impacts associated with a product throughout its life from raw material acquisition through production, use and disposal. LCA can assist in making eco-friendly products.

LCA consists of four elements: Goal and scope definition, Inventory analysis, Life cycle impact assessment (LCIA) and Interpretation. Conducting LCA requires reliable data for inventory analysis. NIRE has been trying to build a "public database" for providing such data with cooperation of Japanese industries. NIRE has also developed LCA software designed to process huge amount of inventory data, and offered the software to more than 150 Japanese industries.

In addition, NIRE has developed a methodology for LCIA, especially focusing on weighting different impact categories such as global warming, ozone layer depletion, acidification and eutrophication.

As part of research in NIRE to improve and enhance safety in our society (i.e., we call the research "social safety engineering"), we are conducting research on the human factors that relate to safety.

We are studying the safety in underground spaces, which are of particular interest in recent years, from the motor physiological, physiological and osychological points of view. In the studies, we are investigating evacuation to the surface from underground as well as human information recognition and behavior characteristics in underground environments. We have also been developing an simulation model of evacuation for safety assessment in which these research results are integrated. In the research, which takes into account the importance of sound and speech information in evacuation or other situations, we have focused on the relationship between various environmental factors in underground and characteristics of sound propagation as well as speech transmission.

Our scope includes influence of ventilation, reverberation, geometric configuration of underground spaces and others on sound propagation and speech transmission in underground tunnels. As an example of this research, we showed that the propagation characteristics of sound in the tunnels with ventilation air flow are complete opposite to those on surface, that is, sound and speech information transmit downwind with difficulty. The phenomenon is demonstrated theoretically with a numerical calculation. 

To achieve further advances in this research, NIRE is promoting studies on human factors from the viewpoints of reducing risk to human beings under various environments.

Reactive chemical materials, of which explosives is a well-known example, are widely used as explosives, fuels, and gas generating agents, which take advantage of their property to generate amounts of energy instantaneously. There are also broad expectations for assuring their safety and for the possibilities of their use in helping solve environmental problems.

In our research on the environment and safety we are enhancing low-environmental-impact demolition techniques by developing a precision initiation system, elucidating the failure phenomenon in materials due to impact loads from earthquakes and other causes, and developing techniques to control blasting vibration, noise, and fly rocks using wave interference.

Methods of our efforts on techniques for safety on the occasion of earthquakes and other major disasters consist of researches on restoring lifelines using explosive welding, and an air jack system for rescues. We are additionally conducting research on a technology for the reuse and environmental impact assessment of the sodium azide-based gas-generating agent used in automobile air bags.