Final answer:
It is generally considered unsafe and illegal to leave a child 6 years or younger unattended in a vehicle.
Step-by-step explanation:
In the United States, the legal age requirement for leaving a child unattended in a vehicle varies from state to state. However, it is generally considered unsafe and illegal to leave a child 6 years or younger alone in a car, regardless of the weather conditions or whether the engine is running or the keys are in the ignition. Parents and caregivers should always prioritize the safety and well-being of children and avoid leaving them unattended in a vehicle.
Learn more about Leaving a child unattended in a vehicle