Can You Suffocate While Sleeping in a Car?

[AdrianaAnn]

Sleeping in a car with the air conditioning on (using internal circulation) and the windows closed can lead to carbon monoxide poisoning, which can be life-threatening in severe cases. If you must sleep in the car, be sure to turn off the air conditioning and avoid closing all the windows completely—leave a small gap in one window. The reasons are: 1. When the engine is running, incomplete combustion of gasoline in the cylinders can produce high concentrations of carbon monoxide. While the car is moving, the air circulates through the air conditioning system, keeping the carbon monoxide concentration inside the car low. 2. However, when the car is stationary with the air conditioning still running and the windows closed, the carbon monoxide emitted by the engine can gradually accumulate, increasing its concentration and leading to poisoning or even death.

[SanColin]

Last week during camping, I specifically tested the safety of sleeping in the car overnight. Modern cars indeed have excellent sealing—carbon dioxide levels noticeably rise within half an hour of closing the windows. It's best to leave a two-finger-width window gap or install a solar-powered exhaust fan costing just a few dozen yuan. If using the air conditioning, remember not to switch to external circulation mode, as the risk of exhaust gas backflow is more dangerous than oxygen deprivation. I always keep a portable oxygen canister in my car, which folds down to the size of a power bank. By the way, that couple in the news two years ago who tragically died while sleeping with the AC on in a garage fell victim to carbon monoxide produced by the continuously running engine. Even outdoors, always park facing the wind to ensure proper air circulation.

[VonCody]

Family road trips with kids often require naps at rest stops. Children are more vulnerable than adults in enclosed vehicles, especially since infants require three times the oxygen. I've found that tilting the sunroof at a 10-degree angle provides the safest ventilation—it keeps rain out while creating airflow. Always park facing the wind direction and avoid low-lying areas. It's heartbreaking to see parents leaving children alone in cars for naps; window condensation signals oxygen deprivation. Most new cars now feature air quality monitoring that alerts even when the engine's off. For older vehicles, I recommend affordable oxygen-deprivation warning stickers (available online) that change color to prompt immediate ventilation.

[DiJoel]

As a truck driver, I've slept in the cab hundreds of times. My experience is to open both the driver and passenger windows about three fingers' width to create diagonal airflow. On rainy days, turn on the air conditioning's external circulation + front windshield defogging mode to ensure the fresh air system works. Be vigilant about carbon monoxide poisoning—install a gas detection app on your phone for real-time monitoring. Once at a rest stop, I saw someone using an umbrella to prop open a gap in the door curtain, which works great in the rain. Remember not to sleep near a running diesel truck, as diesel exhaust has higher concentrations of nitrogen oxides. Now I keep a rechargeable air detector with an alarm function in my vehicle, which gives me much more peace of mind regarding safety.