This European standard specifies general requirements for construction and testing, and specifies the test methods that apply to personal, portable, transportable and fixed apparatus intended for the direct detection and direct concentration measurement of a toxic gas or vapour in workplace air. It applies to apparatus whose primary purpose is to indicate the presence of a toxic gas or vapour in the atmophere with a view to providing an indication or warning of the presence of a toxic hazard within a time of response as specified in prEN 45544-2 and prEN 45544-3.