This paper proposes a method and a device for monitoring biological contamination indoors. The method uses the human body as a primary transducer as it produces a psychosomatic response to a biological agent. It is based on measuring the psychosomatic response to the non-invasive effects of biologic threats posed by such agents. A light permeability sensor for human body is proposed as for psychosomatic response instrumentation. The paper presents the circuit diagram of the device and describes it. It further dwells upon the specifications of an experimental unit created to measure biological contamination. The paper discusses the results of measuring human body’s psychosomatic response to pathogenic molds present indoors. It proves the proposed biological monitoring method advantageous.