Doctor issues warning about major mistake millions make while driving that is ‘slowing your brain down’

A doctor has shared a bleak warning for something you probably don't even think about when you're in your car.

On a hot summer's day, or if you're driving near fumes you don't want to get in your vehicle, you may press the recirculation button, a feature that is close to the air conditioning button on the dashboard.

However, according to Dr Clay Moss, if left on for too long, this button can do some damage to your body, specifically to your brain which can cause it to 'slow down'.

In an Instagram video, the American doctor revealed that leaving this feature on can dramatically affect the air around you, which, as you might expect, can cause huge cognitive risks.

Dr Moss asked in his video: "Did you know there's a single button in your car that could be causing more harm than good?

"You guys remember this little guy right here that we always love putting on?

"That little recirculation symbol stops outside air from getting in, which is great when you're trying to quickly cool off the air on a hot day, but it can have unintended consequences over time."

He continued: "You see, when you're breathing in a sealed car, carbon dioxide builds up pretty quickly. 30 minutes of recirculation and you could easily exceed 12,000ppm [parts per million] of CO2, where your brain literally starts to slow down."

While most modern cars have some ventilation even with the recirculation button on, CO2 levels can still rise, especially with multiple passengers or during longer journeys. High CO2 levels can lead to drowsiness, reduced cognitive function, and slower reaction times, potentially increasing the risk of accidents.

Dr Moss added that, with more passengers in the car 'you could easily hit 2,500 to 3,000ppm of carbon dioxide. That's when you start to get drowsy, foggy and irritable'.

It's not just Dr Moss making the claim, as studies also show how carbon dioxide can accumulate to 'high concentrations' when the recirculation button is used.

A 2018 study found that although CO2 is not poisonous, air inside a car can reach over 2,500 ppm of CO2, which can cause 'detrimental cognitive effects' such as fatigue, concentration issues, drowsiness, lower blood pressure, and a lower heart rate.

And there are other ways this feature could affect you; recirculating air traps moisture inside the car, which can lead to condensation and fogged-up windows, especially in cold or wet weather. This can severely impair visibility and, again, heighten the risk of accidents.

But there's no reason to panic, said Dr Moss, who explained there's a simple solution to ensure you don't run into any problems while out on the road.

He added: "Now, the fix is super easy. You just either crack the window, or switch to the fresh air mode and turn off the recirculation mode for just two minutes. It flushes the CO2 out and keeps your brain sharp.

"Your car's climate settings aren't just about comfort, they mess with your cognition too. So breathe better, drive safe."