The Asuncion Valdivia Heat Illness, Injury, and Fatality Prevention Act of 2025 mandates the Secretary of Labor to promulgate a comprehensive worker heat protection standard. This standard aims to safeguard employees from heat-related injuries and illnesses by establishing the maximum protective program of measures employers must implement. Employers are required to furnish employment and workplaces free from conditions that may cause death or serious physical harm from heat stress, and to comply with all standards, regulations, and orders issued under this Act. The design of these standards will prioritize worker protection, considering demonstrably achievable measures adopted by state plans and leveraging expertise from bodies like the National Institute for Occupational Safety and Health. The Secretary may categorize employers based on industry, work conditions, or heat sources to design effective and practicable programs. The standard will include various protective programs such as engineering controls to eliminate hazardous heat levels, administrative controls to adjust work procedures, and the provision of personal protective equipment at the employer's expense. Further protective measures include health-related protocols like medical symptom monitoring and emergency response, along with comprehensive training requirements for employees and supervisors on recognizing heat illness symptoms and appropriate responses. Employers will also be required to develop and implement a heat illness and injury prevention plan with meaningful employee participation. Core practices mandated for employers include providing suitably cool potable water, periodic paid rest breaks, access to shade or cool-down spaces, and acclimatization policies. The bill specifies that employees must receive regular compensation for required rest breaks, medical removal protection, and training. All required information, including training and plans, must be provided in languages understood by employees. The Secretary is directed to issue an interim final rule within one year of enactment, which will take effect immediately and remain in force until superseded by a final rule. Subsequent rulemaking will follow specific procedures, including a petition process, defined timelines, and transparency requirements for public records. Worker heat protection standards will have the same legal effect as other occupational safety and health standards, with enforcement provisions including a four-year statute of limitations for citations and whistleblower protections for employees. The Secretary of Labor is also tasked with updating the National Agricultural Workers Survey to better identify the incidence of heat-related illness and injury and assess the impact of these new standards.