To help prevent acute and chronic illnesses caused by various kinds of chemical substances and physical hazards, work environments should be monitored with periodic measurements and hazard evaluations. Development and improvement of these measuring and evaluation methods are undertaken in our group, in order to achieve the above objectives for both existing and newly-introduced chemical substances. The development of characterization methods and their application to various hazardous dusts and fumes in the workplace are also performed in relation to their biological effects. Irregular work with organic solvents, such as painting, the cleaning of tanks and maintenance of chemical plants are another focus of our research, with new measurement methods and computer simulation techniques currently being developed for these workplaces.