One of the most serious mistakes is sleeping in a vehicle while its engine is running inside a garage or another enclosed area.
Even if the garage door is partially open, exhaust gases can accumulate under certain conditions. Carbon monoxide may enter the vehicle through ventilation openings or other pathways, and occupants may not notice anything unusual before becoming seriously ill.
A running engine produces exhaust regardless of whether the air conditioning is switched on. The air conditioner does not remove carbon monoxide from exhaust gases and should never be considered a protective measure against poisoning.
Carbon monoxide exposure is especially dangerous during sleep because the affected person may not recognize the early symptoms or wake up before exposure becomes severe.
If a vehicle is running in an enclosed space, everyone should move to fresh air immediately if it is safe to do so. If carbon monoxide exposure is suspected, contact emergency services and do not re-enter the contaminated area until authorities say it is safe.
People who experience headache, dizziness, nausea, chest pain, confusion, or unusual weakness after possible exposure require urgent medical assessment. Severe exposure can cause lasting neurological or cardiac complications even after the person leaves the contaminated environment.
The safest rule is straightforward: never run a fuel-burning vehicle inside an enclosed garage to cool the cabin or provide a place to sleep.
If you need to rest during a journey, choose a designated rest area or another safe location away from enclosed spaces. Whenever possible, turn off the engine and rest in a suitable environment rather than relying on a running vehicle for comfort.
Image 1 — Suggested placement: A realistic photograph of a parked car inside a residential garage, viewed from outside, illustrating the importance of exhaust safety. No text, logos, or dramatic effects.
Chapter 3: Dangerous Habit Number Two — Assuming the Air Conditioning Makes Everything Safe
Air conditioning can make a vehicle more comfortable in hot weather, but comfort does not necessarily indicate safety.
A functioning air-conditioning system cools the cabin by transferring heat. Depending on the vehicle and its ventilation settings, some outside air may enter the cabin while some air is recirculated.