The Silent Danger of Air Recirculation Mode While Driving Long Distances

In both city and long-distance driving, most drivers tend to press the 'air recirculation' button to prevent unpleasant odors from outside. But did you know that keeping this button pressed throughout the journey can become a silent danger leading to hazards? Today, AS AUTO has the answer as to why air recirculation mode is dangerous when driving long distances.

First, let's understand the operating principles of a car's air conditioning system, which has two main modes:

1. Recirculation Mode: The system pulls air inside the cabin to recirculate it and cool it down again quickly. This is ideal for rapidly cooling the cabin initially or when driving through areas with strong odors, smoke, or excessive dust.
2. Fresh Air Mode: The system draws fresh air from the outside of the car, passing it through the filter and evaporator coil to create new, circulating air inside the cabin.
 

The Silent Danger! When the Recirculation Button is Left On

When you keep the recirculation button pressed for a long time, especially when there are multiple passengers, the system repeatedly takes the same air that we have exhaled and cycles it back for cooling inside the car.

What happens is:
- Oxygen (O2) levels decrease: Because no new air is being drawn in from the outside to replenish it.
- Carbon Dioxide (CO2) levels increase: The gas we exhale accumulates more and more within the cabin.

The impact of excessively high CO2 levels directly affects the driver's body and brain, leading to the following symptoms:
- Drowsiness and fatigue
- Headaches and confusion
- Reduced concentration while driving
- Slower decision-making

These symptoms are dangerous signs that can lead to "micro-sleep" (falling asleep at the wheel), which is a major cause of severe road accidents.

 
Correct Usage of the Recirculation Button for Long-Distance Driving
For optimal safety and conditions during a long drive, you should follow these guidelines:

- Initial Stage of the Trip: You can press the "Recirculation Mode" button for about 5–10 minutes to rapidly cool the entire cabin.
- During Long Drives: Once the air is cool, you should turn off the recirculation button and primarily switch to "Fresh Air Mode." This method helps maintain oxygen balance and prevents the accumulation of carbon dioxide, keeping the body feeling fresh and alert.
- Use Only When Necessary: Use the Recirculation Mode only temporarily when driving through areas with high pollution, such as construction zones, factories, or behind vehicles emitting black smoke. Once past that area, quickly switch back to Fresh Air Mode.
- Additional Tip: Every 1–2 hours, you should slightly lower the windows for about 1–2 minutes to allow better air exchange.

In summary: The air recirculation button is a feature many people only think of using in the city to block out smells. However, driving safely on long trips requires using both the Fresh Air and Recirculation buttons appropriately.