Direct Hazard Analysis The MHA method is intended to address the four major hazards usually of concern in process safety and their impacts on people and the environment. However, some PHA practitioners apply PHA methods to other types of hazards. Therefore, in an extension of the MHA method called Direct Hazard Analysis (DHA) other hazard types are addressed. Each hazard type uses a structured list of categories of initiating events and ways they can occur. An example of such a list is provided in Table 2 for the hazard of over-pressurization. Such lists can be developed for any hazard. An important precursor to a DHA study, indeed for many PHA studies, is the performance of a Hazard Identification (HAZID) study in which hazards in each area of the process are identified using a checklist of hazards. A HAZID worksheet is usually completed (see Figure 4). Process materials are considered, material safety data sheets and other documents are reviewed, and known hazards are listed. The HAZID study allows a determination to be made of which hazards will be addressed using PHA and which PHA techniques should be used for which types of hazards. Other hazards are managed through other occupational health and safety programs, for example, using simple checklists or Job Hazard Analysis.