Acceptable Benzene level indoors is 50 mg per sq. ft… A car parked indoors with the windows closed will contain 400-800 mg of Benzene.
If parked outdoors under the sun at a temperature above 60 degrees F, the Benzene level goes up to 2000-4000 mg, 40 times the acceptable level… & the people inside the car will inevitably inhale an excess amount of the toxins.
It is recommended that you open the windows and door to give time for the interior to air out before you enter. Benzene is a toxin that affects your kidney and liver, and is very difficult for your body to expel this toxic stuff.