Measurement of exposure to gaseous contaminants

The indoor exposure of occupants to gaseous contaminants is often simulated by use of tracer gas. In this paper the method of tracer gas concentration measurement, including characteristics of the measuring instrument (response time, measuring range, etc.) and analyses of the collected date for correct assessment of exposure was studied. Breathing thermal manikin was used to resemble human body with the free convection flow and the flow of respiration. Personalized ventilation was used to generate invading ventilation flow from front. CO₂ was released at the armpits and N₂O at the groins to simulate respective bio-effluents generated by the body. The tracer gas concentration at the mouth/nose and around the manikin was measured with gas analysers with short and long response time. The comparison of the results show that the response time of the analysers and gas concentration measurements only during the period of inhalation are important for accurate exposure assessment.