Final answer:
Seat belt usage requirements for children depend on age, weight, and local laws. Generally, children who have outgrown child safety seats must use a regular seat belt. It's vital to consult local regulations for exact requirements.
Step-by-step explanation:
The question about seat belt usage requirements for a passenger under 8 years old and weighing more than 80 pounds involves understanding health and safety regulations, which can differ based on jurisdiction. Generally, children under a certain age or weight need to use a child safety seat, but once they exceed these limits, they usually must transition to using a regular seat belt. However, the specific rules can vary by state or country, so it is essential to check local laws and regulations which are designed to ensure the safety of passengers and decrease the risk of injury during a car crash.