A doctor has shocked millions of drivers after revealing that a common setting in your car could be quietly sabotaging your brain function.
Dr Clay Moss has racked up more than 6.9million views on a video after issuing a blunt warning about the recirculation button – a familiar feature most drivers flick on without a second thought.
‘Did you know there’s a single button in your car that could be causing more harm than good?’ the American expert began in the eye-opening video.
‘You guys remember this little guy right here that we always love putting on?’ he said, pointing to the well-known recirculation symbol, which is typically found on the dashboard near the air conditioning controls.
‘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 explained.
It’s not just smog it’s stopping, it’s your the brain from functioning at its best, too.
While many hit the button to block pollution or get cool air flowing fast, Dr Moss says keeping the car in recirculation mode for too long can quietly poison the air inside.
‘You see, when you’re breathing in a sealed car, carbon dioxide builds up pretty quickly. Thirty minutes of recirculation and you could easily exceed 12,000 PPM [parts per million] of CO2, where your brain literally starts to slow down.’
U.S. doctor Clay Moss (pictured) has shocked millions of drivers after revealing that a common setting in your car could be quietly sabotaging your brain function
With two or three passengers, the issue gets worse: ‘You could easily hit 2500–3000ppm of carbon dioxide. That’s when you start to get drowsy, foggy and irritable.’
And he’s not just talking hypothetically. In a 2018 study on U.S. driving conditions, the levels of carbon dioxide recorded were alarming.
It found that under recirculation mode, even single-occupant drives can reach up to 2,500ppm in longer or multi-occupant trips, well above cognitive risk thresholds.
According to Dr Moss, that’s where cognitive performance drops, reaction time slows, and you’re more prone to drowsiness and brain fog.
Before you panic, Dr Moss says there’s an easy hack that takes just seconds and could make a massive difference to your alertness behind the wheel.
‘Now, the fix is super easy,’ he said. ‘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,’ he added. ‘So breathe better, drive safe.’
The clip has sparked major debate online, with many drivers admitting they had no idea something so minor could affect their brain so dramatically.
Many of us hit the recirculation button (middle-right) to block pollution or get cool air flowing fast. However Dr Moss says keeping your car in this mode for too long can quietly poison the air inside, and mess with your head
‘I drive to work two hours each way every day… is this why I get so sleepy by the time I get to my destination?’ one person commented.
‘I’ve actually never used it to cool off, but I’ve used it when driving through stuff that I don’t want getting in my car (like truck exhaust, dust, dirt, grass, etc),’ said another.
‘Is that why I suffer from road rage?’ Another joked.
Others pointed out they use it ‘all the time to avoid city smog,’ while some confessed that they’ve never switched it off.
However, in a silver lining, more modern cars have an automatic recirculation mode that have timers to effectively shut-off by themselves to keep drivers safe.
