The National Center for Biotechnology Information's website states that there is no apparent health hazard of a motor vehicle's indoor air.
The National Center for Biotechnology Information (NCBI) abstract page mentioned a study report titled ‘Toxicity of parked motor vehicle indoor air’ which states that the interior of motor vehicles is made of a wide variety of synthetic materials, which emit volatile organic compounds (VOC) and researchers had tested the health effects of emissions from vehicles exposed to "parked in sunshine" conditions and came out with the conclusion that there is no direct toxicity after metabolic activation and they not found any substances that are potential in motor vehicle indoor air, neither from new car or used car. The abstract added the investigations indicated no apparent health hazard of a parked motor vehicle's indoor air.
The American Cancer Society (ACS) website reports that based on the evidence from studies that included lab animals and human beings, benzene is known to be a cause for cancer and the ACS also states about the link between benzene and cancer has largely focused on leukaemia and other cancers of blood cells. However, no published reports and studies are confirming that benzene gas produced from the car dashboard, seat or air freshener causes cancer in humans. This is a false claim.