The question of the possibility of suffocation in a car arises for many people - especially for parents who leave their children in the car “for a minute”, or for drivers who sleep in a car with the engine running. There are a lot of myths circulating on the Internet: from statements that “death in 10 minutes in a closed car is guaranteed,” to stories about people who “slept the night in a garage and did not feel any discomfort.” Where is truth and where is fiction?
To answer this question, you need to understand three key factors: volume of oxygen in the cabin, the rate of its consumption and accumulation of carbon dioxide (CO₂). It is also critical to understand the difference between situations with off and engine turned on — in the latter case, the risks increase significantly due to exhaust gases. In this article we will analyze real cases, physiological norms and provide a checklist of actions to prevent dangerous situations.
Physiology of breathing: how much oxygen does a person need?
The average adult consumes about 550 liters of oxygen per day, or ~23 liters per hour. During physical stress (for example, panic), this figure can double. The volume of air inside a passenger car is approximately 2.5–3.5 m³ (2500–3500 liters), of which oxygen is about 21% (525–735 liters). It would seem that the reserve will be enough for 20–30 hours, but in practice everything is more complicated.
The problem is not only a decrease in oxygen, but also an accumulation carbon dioxide (CO₂). Already at a CO₂ concentration of 0.5% (5000 ppm) a person feels headache and drowsiness, and when 8–10% loss of consciousness occurs. In a closed cabin without ventilation, this threshold is reached much faster than oxygen is depleted. For example, in experiments with two people in a car, CO₂ levels exceeded dangerous values within 1.5–2 hours.
- 🧠 Oxygen (O₂): the norm in the air is 20.9%. When it drops to 17%, coordination begins to deteriorate, and to 12%, nausea begins.
- 💨 Carbon dioxide (CO₂): safe level - up to 1000 ppm. At 5000 ppm - dizziness, at 40,000 ppm - death.
- ⏳ Time of critical accumulation of CO₂: 1 person - 4–6 hours, 2 people — 1.5–2 hours (with the engine off).
Important: these calculations are valid for hermetically sealed interior. In practice, even micro-cracks in door seals or a slightly open window by 1–2 cm increases the time to dangerous concentrations in 3–5 times.
Hazard #1: Exhaust fumes while the engine is running
If in a car with engine off the risk of suffocation is minimal (except in extreme cases), then when engine turned on the situation is changing dramatically. Exhaust gases contain Carbon monoxide (CO) is a colorless and odorless gas that blocks the blood's ability to carry oxygen.. The CO concentration in gasoline engine exhaust can reach 70 000 ppm (for comparison: a lethal dose is 1000 ppm for 1 hour).
The classic poisoning scenario: the driver or passenger is sleeping in the car with the heating (stove) on, and the exhaust pipe is clogged with snow or the car is parked in the garage. In this case, CO enters the cabin through the ventilation holes, and the person loses consciousness after 10–30 minuteswithout having time to wake up. According to statistics from the Ministry of Emergency Situations, every year in Russia 150–200 deaths for this reason.
⚠️ Attention: Even if windows are slightly open, carbon monoxide can accumulate to lethal concentrations. In 2022, a family of three died in Moscow after sleeping in a car with the engine running and the window open 5 cm.
| CO concentration (ppm) | Symptoms | Exposure time to death |
|---|---|---|
| 50 | Headache after 6–8 hours | No data |
| 200 | Nausea, weakness after 2–3 hours | 10+ hours |
| 1000 | Loss of consciousness after 1 hour | 1–2 hours |
| 5000 | Coma after 20–30 minutes | 30–60 minutes |
This scenario is especially dangerous for used cars, where exhaust system malfunctions are possible (cracks in the muffler, burnt gaskets). For example, in Toyota Camry Models from 2010 to 2015 often experience problems with exhaust pipe corrosion, which causes gases to enter the cabin even with the windows closed.
Before sleeping in the car, check the exhaust pipe for blockages (snow, dirt, foreign objects). Even a small plug can send gases back into the cabin.
Real cases: statistics and examples
Analysis of incidents shows that the majority of deaths are associated not with lack of oxygen, but with carbon monoxide or overheating (in hot weather). Here are some documented examples:
- 🚗 USA, 2019: A 6-year-old child died in a closed car after 2 hours at a temperature of +35°C. The cause is heatstroke, not suffocation.
- 🚗 Russia, 2021: a man fell asleep in a garage with the engine running Lada Vesta. The CO level in the blood was 50% (lethal dose - 30–40%).
- 🚗 Japan, 2020: A couple tried to stay warm in their car during a snowstorm. The windows were closed and the engine was running for 4 hours. Both were starved of oxygen due to CO₂ buildup (no CO!).
Fun fact: in the channel experiment MythBusters the volunteer spent 8 hours in a hermetically sealed car without any health consequences. However, in real conditions it is rarely possible to achieve complete sealing, and panic or physical activity accelerates oxygen consumption.
Details of the MythBusters experiment
A car was used during the test Honda Accord 2005. The participant sat motionless, breathing was monitored by sensors. O₂ levels dropped from 20.9% to 17.5% in 8 hours and CO₂ rose to 3000 ppm (causing a slight headache). The experiment proved that the main risk is not suffocation, but hypercapnia (CO₂ poisoning).
How to Prevent Choking: Safety Checklist
If you must spend time in a closed car (for example, while sleeping or waiting), follow these rules:
☑️Safety inside the car
For owners of cars with remote start (for example, Nissan Qashqai or Hyundai Tucson) It is important to remember: even if the engine is started remotely, exhaust gases can enter the cabin through the ventilation system. In models with climate control (for example, Volkswagen Tiguan) when the engine is running, recirculation is automatically turned on, which aggravates the problem.
If you sleep in your car regularly (for example, when traveling), consider the following options:
- 🔋 Portable CO sensor (for example, X-Sense CO03D) - signals when 50 ppm is exceeded.
- 🌬️ Battery powered fan for forced air circulation.
- 🚪 Emergency hammer for breaking glass (relevant if the door is jammed).
Even with the engine off, never leave sleeping children or pets in the car. The temperature in the cabin can rise to +50°C in 20 minutes (in summer) or drop to -10°C (in winter), which is deadly.
Myths about suffocation in a car: what is it really like?
Let's look at the popular misconceptions that are spreading on social networks and forums:
- “You can suffocate in a car in 10 minutes.” - lie. Even with complete sealing, this will take at least 4-6 hours (for one person). The exception is if the cabin is filled with exhaust gases.
- “A slightly open window will save you from carbon monoxide” - not always. If the car is parked in a garage or next to an obstacle (such as a snowdrift), CO can accumulate even with the window open.
- "Diesel engines are safer than gasoline engines" - no. Diesel exhaust contains less CO, but more
NO₂(nitric acid), which irritates the lungs and worsens suffocation. - "The air conditioner removes CO from the air" - no! An air conditioner cools the air but does not filter carbon monoxide. This requires specialized filters (for example, HEPA + activated carbon).
Another common misconception: “If you turn the heater on full, the interior will be ventilated." In fact, the stove circulates the same air in a circle (recirculation), without adding fresh air. To really ventilate the car, you need open the windows or turn on the air flow from the street (turning off recirculation).
What to do if you feel symptoms of suffocation
Signs of lack of oxygen or CO poisoning: dizziness, tinnitus, rapid breathing, nausea. If you find yourself in this situation:
- Immediately open all windows or get out of the car.
- If the engine was running - turn it off and leave the salon.
- In case of severe discomfort call an ambulance (carbon monoxide is removed from the body only with the help of oxygen therapy).
- If there is someone nearby in an unconscious state - take him out into the fresh air and begin artificial respiration.
⚠️ Attention: Do not try to “wait out” symptoms inside the car. Carbon monoxide binds to hemoglobin 200 times more reactive than oxygen, and without medical attention a person can die even after going outside (due to residual CO in the blood).
In the case of children or animals, act immediately: their metabolism is faster, and critical conditions occur in 2–3 times fasterthan in adults. For example, a dog in a closed car at +30°C gets heatstroke within 15–20 minutes.
FAQ: Frequently asked questions about cabin safety
Is it possible to sleep in a car with the engine turned off in winter?
Yes, but there are two factors to consider: temperature and ventilation. At -10°C and below the risk of hypothermia is high, so use a sleeping bag or blanket. Open the window 1–2 cm for air flow. In cold weather, it is better to periodically run the engine for 5-10 minutes (with the window open) to warm up.
Is it true that you can’t suffocate in new cars due to improved ventilation?
No, it's a myth. Modern cars (eg. Tesla Model 3 or BMW X5) are more airtight than the old ones, but their ventilation systems are not designed for long periods of time with the engine turned off. Moreover, in cars with electric drive (for example, Nissan Leaf) there is no risk of CO poisoning, but CO₂ accumulation remains a problem.
How to check whether exhaust gases are entering the cabin?
Carry out a test: start the engine, close all the windows and turn on the heater to maximum airflow. Bring it to the vents wet wipe. If gray or black marks remain on it, exhaust gases enter the cabin. You can also use CO detector (price from 1500 ₽).
What is more dangerous: lack of oxygen or carbon monoxide?
Carbon monoxide (CO) in 100 times more dangerous. Oxygen deficiency develops slowly (hours), while CO poisoning results in death within minutes. For example, at a CO concentration of 1000 ppm, a person loses consciousness after 1 hour, and at 5000 ppm, after 10–15 minutes.
Can a car be used as a shelter from frost or heat?
Yes, but with caution. In summer, at +30°C, the temperature in the cabin rises to +50°C in 20 minutes - this is deadly. In winter, the risk of hypothermia is lower, but without heating (for example, Webasto) long stay is fraught with frostbite. The best option is start the engine periodically (with an open window) or use independent heaters (for example, Planar 2D).