However, the system is not designed to protect occupants from carbon monoxide poisoning. If exhaust gases enter the cabin, the fact that the air feels cool does not mean the environment is safe.
Another concern is the condition of the vehicle itself. Damaged exhaust components, leaks, or an obstructed tailpipe can increase the risk of exhaust gases entering areas where people are sitting or sleeping.
Parking location also matters. Vehicles parked close to walls, in confined spaces, or near other running engines may be exposed to exhaust under unfavorable conditions.
Extreme outdoor temperatures create a separate hazard. If the engine or air conditioning stops working, the cabin may heat up rapidly in hot weather. This is particularly dangerous for children, older adults, and people with medical conditions that affect temperature regulation.
Cold weather can also create risks when a vehicle is used for prolonged shelter without adequate preparation.
Drivers should never assume that a vehicle will remain at a safe temperature indefinitely. Mechanical failures, fuel depletion, and changing weather conditions can alter the environment while someone is asleep.
Before a journey, ensure that the vehicle is maintained properly and that the exhaust system is in good condition. Never ignore unusual exhaust odors, although the absence of an odor does not rule out carbon monoxide.
If you need a nap, the safest option is to use a designated rest facility when possible. If you remain in the vehicle, choose a safe location, follow the manufacturer's operating guidance, and do not sleep in an enclosed garage with the engine running.
Chapter 4: Three More Dangerous Habits Drivers Should Avoid
In addition to running an engine in an enclosed space and assuming that air conditioning guarantees safety, several other habits can increase the risks associated with resting in a parked car.
Habit Number Three: Ignoring Exhaust-System Problems
A damaged exhaust system can allow combustion gases to escape in places where they should not. Drivers should arrange an inspection if they notice unusual exhaust sounds, visible damage, or other signs of a mechanical problem.