To prevent workers’ acute and chronic illnesses from various kinds of chemical substances and physical hazards, work environments should be controlled through periodic measurements and evaluations. Development and improvement of these measuring and evaluation methods are undertaken at our research group in order to achieve the above objectives for existing and new chemical substances and physical factors. Development of characterization methods for various hazardous dusts and fumes in the workplace and also anticipated hazards of new materials such as nano-particles are intensively studied. Synthesis of new adsorbents applicable to respirators and treatment for ventilation exhaust, and performance evaluation of LEV has been continually studied.