The designation of hazardous areas is typically the responsibility of regulatory authorities or government agencies in charge of health and safety regulations. In some countries, there may be multiple regulatory bodies involved in the designation of hazardous areas, such as OSHA in the United States, ATEX in Europe, or NEPSI in China. These organizations determine the criteria that define hazardous areas and set the guidelines for the equipment and safety measures required in those areas to minimize the risk of accidents, such as fires or explosions. It is important to follow the guidelines set by these regulatory bodies to ensure the safety of workers and the public in hazardous areas.