The foregoing sections have introduced the various classes of hazardous chemicals, their hazard criteria, effects they exert on human health, and the technical measures that one may adopt in order to contain and / or mitigate the associated danger in working with them. Thus it may be appropriate to summarize the entire process of hazard identification and management by means of layered or step-by-step scheme. Such a decision tree is presented in fig. 1. It is expected to provide a structured approach to selection and admittance of a chemical for use in laboratory research.