You should not leave a child unattended in a motor vehicle for any length of time. If children are trapped inside cars—especially in hot weather—they can suffer from heat exhaustion or heat stroke in a matter of minutes, leading to permanent disability or death. Heat stroke, also known as hyperthermia, can cause shock, seizures, irregular heartbeat, and heart attack, as well as brain, liver, and kidney damage. Leaving a child unattended in a car is also a form of neglectful supervision that is investigated by Child Protective Services.

In Missouri, leaving a child unattended in a motor vehicle is considered a serious matter, especially under conditions that pose a risk to the child's health and safety, such as extreme temperatures. Missouri law, under Section 568.034 RSMo, specifically prohibits leaving a child younger than ten years old unattended in a motor vehicle if the motor vehicle's engine is running or if the health of the child is in danger. Violation of this statute can result in a class C misdemeanor, and if the child suffers injuries, the charge can escalate to a class A misdemeanor or even a felony, depending on the severity of the injuries. Additionally, such an act can be deemed as neglectful supervision and may trigger an investigation by Child Protective Services (CPS), which could lead to further legal consequences, including the possibility of losing custody of the child. It is important for parents and guardians to understand the risks associated with leaving children unattended in vehicles and to take appropriate measures to ensure their safety.