A car parked for the whole day in the shade with the windows closed can contain 400-800 mg of Benzene. If you are parked in the sun at a temperature above 16 degrees, the benzene level reaches up to 2000-4000 mg, which is 40 times higher than the permissible level.
Staying in the car with the windows closed, people inhale excessive amounts of benzene. Benzene is a toxin that affects kidneys, bones and liver. Moreover, the body finds it very difficult to remove this toxic substance. Cars have user manuals, which say that before turning on the air conditioning, you should open the windows for 2 minutes. The manual does not state the reason; it only gives the hint of a better vehicle performance.
According to the research, before the air conditioner starts to cool the air, it releases hot air with benzene, heated in plastic. This toxin can cause cancer (one needs some time to notice the smell of heated plastic in the car). Therefore, it is important to be on the safe side and leave the window open for a few minutes.
Do not turn on the air conditioner immediately after starting the car!
First of all, you need to open the windows for a few minutes. Then you can turn on the air conditioner. Keep the windows open for a few minutes after the car is started. Many of unbound hydrocarbons contained in gasoline (especially aromatic ones, such as benzene) and various additives are carcinogenic.