What is the correct federal agency that establishes recommended exposure limits (RELs)?

The correct answer is NIOSH, which stands for the National Institute for Occupational Safety and Health. NIOSH is responsible for conducting research and making recommendations for the prevention of work-related injuries and illnesses. This includes establishing Recommended Exposure Limits (RELs) for various hazardous substances. These RELs are intended to serve as guidelines for the maximum allowable concentrations of hazardous substances in the workplace, aiming to protect workers' health.

NIOSH's focus is specifically on occupational safety and health, and its recommendations supplement those of other organizations, such as OSHA (Occupational Safety and Health Administration), which enforces workplace safety regulations. However, NIOSH is separate from OSHA and plays a key role in the area of research and development of safety standards, making its recommended exposure limits particularly focused on promoting safe working conditions based on scientific evidence.

In contrast, the EPA (Environmental Protection Agency) primarily deals with environmental protection and regulation of harmful substances in the environment, and DOT (Department of Transportation) focuses on transportation safety regulations rather than occupational safety. Hence, while these agencies play important roles in their respective domains, it is NIOSH that sets the recommended exposure limits specifically for hazardous substances in the workplace.