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, ...

But one common feature in nearly every car, if used excessively, could put your life in danger. ... (NIH), when people breathe out, carbon dioxide (CO 2) is released inside the vehicle, ...