Application of tracer gas analysis to industrial hygiene investigations.

This article discusses the application of tracer gas methods to industrial hygiene investigations. It introduces the basic concepts necessary to understand the application of tracer gas methods to particular airflow and contaminant movement measurements. It provides an overview of existing methods which can be used to obtain quantitative data on a variety of airflow and contaminant movement related questions which often are of interest to the industrial hygienist. A general description of each method is given, along with the pertinent equations used to extract quantitative information from the test results. Selected results from the use of each method are summarized. It will discuss the use of tracer methods to evaluate building and industrial ventilation systems and methods currently being developed to measure ventilation effectiveness. It will also discuss how to use ventilation measurement along with contaminant concentration measurements to infer contaminant source strengths. It will review the methods used to measure the performance of various systems designed to contain an airborne hazardous substance and assess the potential for spread of this substance into non-containment areas. The topics treated are the evaluation of fume hood re-circulation and re-entrainment, the evaluation of re-entrainment by building air intakes, the simulation of hazardous releases and the performance of secondary containment ventilated enclosures using tracer gases. Tracer gas methods have been used for measuring building ventilation and air infiltration rates measuring airflow rates in ducts testing fume hoods for re-- circulation and re-entrainment measuring exhaust re-circulation and re-entrainment estimating contaminant source strengths evaluating performance of ventilation systems and ventilation effectiveness characterizating hazardous substance releases - evaluating temporary safe havens determining flow patterns and flow path tracing evaluating airborne hazardous substance containment validating models which predict airflow and contaminant levels. Tracer gas methods have been used in office buildings, hospitals, schools, laboratories, chemical facilities, nuclear power plants, military facilities, semi-conductor fabrication facilities, pulp and paper mills, pharmaceutical facilities and petrochemical plants. In most applications, tracer gas methods are analytical tools which provide accurate means of determining airflow related parameters which are useful to industrial hygienists and in many situations are the only means of obtaining quantitative information. However, these methods are not yet widely known or used outside the research community.