Final answer:
The OSHA Time Weighted Average (TWA) is a permissible exposure limit over an 8-hour workday, intended to protect workers from long-term exposure to hazardous substances and ensure workplace safety.
Step-by-step explanation:
The OSHA Time Weighted Average (TWA) is defined as Option 3: A permissible exposure limit over an 8-hour workday. This standard is set by the Occupational Safety and Health Administration (OSHA) to limit workers' exposure to hazardous substances and ensure safety in the workplace. By setting exposure limits, OSHA aims to protect workers from the health risks associated with long-term exposure to harmful chemicals and noise levels. Employers are responsible for monitoring the workplace and ensuring that exposure levels do not exceed these limits over the course of an 8-hour work day. Additionally, they must adhere to OSHA standards by providing safety training, necessary personal protective equipment, and medical tests, as well as maintaining accurate records of work-related injuries and illnesses.