How Long Can a Person Stay in a Closed Car Space?

[MarcusDella]

The interior of a car is not completely sealed, so a person can stay inside for many days without issues. However, the engine should not be left running because exhaust fumes from a stationary car can enter the cabin, leading to insufficient oxygen. Below are relevant instructions for staying in a car: 1. Parking location: Park the car in an open, spacious, and well-ventilated area with the front facing the wind direction to allow exhaust fumes to disperse. Avoid parking in unventilated areas like enclosed parking lots or small indoor spaces. 2. Switch from recirculation mode to fresh air mode: Do not keep the recirculation mode on for too long, as it reduces the air inside the car and increases carbon monoxide levels, which can lead to poisoning and even death.

[IslaRose]

That day I took my child to the mall and temporarily got out of the car to buy something. Afraid he might wander off, I locked the car doors. When I returned, I found him pale and gasping for breath. Later, after researching, I learned that the air in a car can't last more than two or three hours: an adult sitting quietly consumes about 25 liters of oxygen per hour, and the total oxygen in an average car is just over 1,000 liters. This doesn't even account for the carbon dioxide we exhale, which can cause headaches and nausea when its concentration exceeds 5%. The most frightening part is running the air conditioner in summer, as the carbon monoxide produced by idling engines can seep into the cabin. Since that incident, I've made it a habit to always crack the window when someone is in the car, and now I don't dare to wait in a parked car for more than half an hour.

[OLily]

Once during a long trip, I took a nap in my car at a rest area and woke up with a tight throat and cold sweat. Later, I figured out that a sealed car cabin is like a gradually tightening plastic bag. A sedan's interior space is at most three cubic meters, but only 21% of that is usable oxygen. A person consumes 0.3 liters of oxygen per minute at rest, and double that during activity. What's more troublesome is the rapid accumulation of carbon dioxide—sleeping for two hours can raise its concentration to dangerous levels. I personally like to eat breakfast in the car and found that keeping the sunroof open for ventilation helps a lot. A reminder to everyone: don’t be as careless as I was, especially when traveling with elderly or children. Cracking a window slightly is the safest option.

[VonLawson]

My friend's car window seals had aged, so we tested how long we could last with them completely closed. Four grown men sat inside chatting, and within 50 minutes, someone started yawning and feeling drowsy. We had a detector with us, which showed oxygen levels dropping to 19% and carbon dioxide exceeding 0.5%. The experiment's conclusion was clear: a single person in a quiet state could last up to three hours at most, but with multiple people or heightened emotions, the time was halved. Later, I saw a fire department's educational video mentioning that there are cases every year of intoxicated people suffocating in cars. Now, whenever I park to smoke, I lower the window by two fingers' width to maintain air circulation.

[StJuliet]

Last time during a heavy rainstorm, I was trapped in my car with no phone signal and too scared to get out. Staring at my watch for over forty minutes, I felt my breathing getting heavier. I looked up data from automotive engineers: the total air volume in an average sedan is enough for breathing for 100 hours, but this is a trap. The accumulation of carbon dioxide is the deadly factor. Normal air contains 0.04% CO2, but when the concentration rises to 1%, dizziness sets in. I experienced that chest-tightening feeling firsthand. Extra caution is needed when sleeping in the car with AC on during summer—even with the external circulation on, prolonged periods can be dangerous. I recommend keeping a window breaker in your car; it could save your life in an emergency.

[SanAdalynn]

I once tried sleeping in the car during camping. Even with the windows slightly open, I still woke up feeling stuffy in the middle of the night. Did the math: the car's sealing is better than expected, with an air exchange rate of less than 0.5 times per hour. The human body is like an oxygen-consuming machine, using about 0.25 liters per minute even while sleeping. Winter is more troublesome as the heater makes the air even drier. I found that placing potted plants in the car helps a bit, as green plants can convert CO2 during the day. But the best solution is regular ventilation—now I open the door every twenty minutes during breaks to let fresh air in.