Hi Friends here is something interesting I found on net... It's purely cut and paste..
Analysis: While it isn't 100% false, the above text is a font of misinformation.
Starting with the basics, it's true that benzene is a toxic chemical known to produce a variety of ill health effects, including anemia and cancer (specifically leukemia) in humans.
The substance occurs both naturally (mainly as a component of crude oil) and as a byproduct of human activities, e.g. as a component of petroleum-based products (such as gasoline) and products manufactured using benzene as a solvent (such as plastics, synthetic fibers, dyes, glues, detergents, and drugs). It's also a constituent of tobacco smoke.
Low levels of benzene are typically present in outdoor air due to automobile exhaust and industrial emissions. Thanks to vapors emitted by household products such as glues, paints, and furniture wax, even higher levels of benzene can sometimes be found in indoor air, especially in new buildings.
Benzene in cars
Do automobile dashboards, door panels, seats, and other interior components emit benzene, as claimed in the email? Most likely. In most cars these items are made from plastics, synthetic fabrics, and glues, some of which are manufactured using benzene. According to scientists, such items may "off-gas" trace amounts of benzene, especially under hot weather conditions.
As to car air fresheners, there's precious little information available about the ingredients, though one European study found that some household air fresheners emit measurable amounts of benzene. It's not inconceivable that some car air fresheners do, too.
The crucial question is how much. Might all of these potential emitters cumulatively give off enough benzene to harm your health?
What the scientists say
Most of the published studies wherein benzene levels were measured inside passenger vehicles have been done under driving conditions, in traffic. So, while such studies have indeed found that in-vehicle benzene levels can significantly exceed those outside the vehicle, and could pose a human health hazard, this is mainly attributed to the presence of exhaust fumes.
Also, the amounts of benzene actually detected by researchers, albeit significant, were much, much smaller than the amounts stated in the email. A 2006 study summarizing all the data collected to date reported in-vehicle benzene levels from exhaust fumes ranging from .013 mg to .56 mg per cubic meter — a far cry from the 400 mg to 4,000 mg per square foot (do they mean cubic foot?) reported in the email.
Benzene levels in parked cars
In the one study I was able to find that measured benzene levels inside parked cars with their engines turned off, the results were more benign. Toxicologists took samples of the air inside both a new and a used vehicle under simulated hot-sunlight conditions, measuring the levels of volatile organic compounds (VOCs) including C3- and C4-alkylbenzenes, and exposing human and animal cells to the samples to determine their toxicity. Despite the detectable presence of VOCs (a total of 10.9 mg per cubic meter in the new car and 1.2 mg per cubic meter in the old car), no toxic effects were observed. Apart from noting the slight possibility that allergy-prone individuals might find their condition exacerbated by exposure to such compounds, the study concluded there is "no apparent health hazard of parked motor vehicle indoor air."
If in doubt, ventilate
Despite this finding, some drivers may still be concerned about the presence of any benzene vapors inside their car, especially given the World Health Organization's stated position that there is "no safe level of exposure" to the carcinogen. They may also worry, per the email warning above, that turning on the vehicle's air conditioner might exacerbate their exposure to trapped toxins by recirculating contaminated air. If that's the case, there's no harm done — and much peace of mind to be gained — by simply opening the windows and ventilating the car before turning it on....unquote