Is your car killing you with benzene?

By Ted Gansler, MD, MBA

An e-mail message that may have come into your inbox recently claims that dangerous levels of a cancer-causing chemical (benzene) are released from the plastic surfaces of automobile interiors. The e-mail recommends opening the vehicle’s windows to remove the benzene before using the air conditioner.


Although benzene is linked to leukemia, very little research has looked at whether the interior surfaces of cars release dangerous amounts of benzene, and the information that is available does not support the e-mail’s claims. [more]

Let’s break the message down and compare the claims with the facts.


Here is the e-mail message (this links to, which is not affiliated with or ACS)



And here’s a point-by-point comparison of the claims and the facts:


Claim: My car’s manual says to roll down the windows to let out all the hot air before turning on the A/C. WHY?

Fact: On a sunny day, the temperature in a parked car can be more than 40 degrees (Fahrenheit) higher than the outside air. Opening the windows is the fastest way to exchange the hot interior air with the cooler outside air. Once that is done, the air conditioner can make the interior cooler than the outside air. The manual’s recommendation is probably focused on passenger comfort rather than toxicology.


No wonder more folks are dying from cancer than ever before.

Fact: Actually, the age-adjusted cancer death rates in the United States have been decreasing for the past 2 decades.


Please do NOT turn on A/C as soon as you enter the car. Open the windows after you enter your car, and then turn ON the AC after a couple of minutes. Here’s why: According to research, the car’s dashboard, seats, a/c ducts in fact ALL of the plastic objects in your vehicle, emit Benzene, a Cancer causing toxin. A BIG CARCINOGEN… Prolonged exposure will cause Leukemia and increases the risk of some cancers.

Fact: Benzene is known to cause cancer, based on evidence from studies in both people and laboratory animals. The link between benzene and cancer has largely focused on leukemia and other cancers of blood cells. Rates of leukemia, particularly acute myeloid leukemia (AML), have been found to be higher in studies of workers exposed to high levels of benzene, such as those in the chemical, shoemaking, and oil refining industries.


Some studies have also suggested links to acute lymphocytic leukemia (ALL) in children and to chronic lymphocytic leukemia (CLL) and other blood-related cancers, such as multiple myeloma and non-Hodgkin lymphoma, in adults. However, the evidence is not as strong for these cancers.


A German study published in 2007 specifically researching the air inside parked cars did not find a hazard to human health. Their analysis detected some cancer-causing chemicals and others that are considered probable or possible carcinogens, but these chemicals were present at levels similar to those found in the air of buildings. Some chemicals that are similar to benzene were found, but benzene was not reported in the results of this study.


Acceptable Benzene level indoors is: 50mg per sq.ft. A car parked indoors, with 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. People who get into the car, keeping the windows closed, will inevitably inhale, in quick succession, excessive amounts of the BENZENE toxin.

Fact: The standard way to report levels of chemicals in air is mass per volume (for example, mg per cubic meter or cubic foot), not mass per area (mg per square foot). Although this is a technical detail, it suggests that the authors of this e-mail may have limited knowledge of the basic scientific principles of this topic.


Furthermore, United States regulations do not specify any single acceptable benzene level. The National Institute for Occupational Safety and Health (NIOSH) has a limit for short-term (15 minute) workplace exposure (3.2 mg per cubic meter) and for average workday exposure ( 0.32 mg per cubic meter). So, the benzene level stated in the e-mail (recalculated as mg per cubic meter) as acceptable is between the NIOSH levels for short-term and daily exposure.


Another blow against this claim comes from the German study previously mentioned. It measured the level of a whole group of chemicals in a new car and an older car “parked in sunshine.” Levels were higher in the new car than the old one, but still 1/10 of the level claimed in the e-mail for benzene alone (and, benzene was not even among the more than 40 chemicals recognized in the study).


Several other studies — from Germany, South Korea, and the United States — have looked at benzene levels in moving cars. These levels have ranged from 0.013 to 0.560 mg per cubic meter. The high range of these reports exceeds the NIOSH chronic exposure limit, though in the US study, the highest level (0.045 mg per cubic meter) was found in a car the researchers described as malfunctioning.


The Upshot


We found no published studies that confirm the claims of this e-mail. Benzene levels that exceed recommendations for chronic workplace exposure have been observed in some moving cars, but these levels seem unlikely in properly maintained cars.


Still, if you’re concerned about benzene levels in cars (especially in cars with the engine running), there’s no harm in opening the windows periodically or using an air-conditioner setting that circulates air from outside the vehicle.


And there are other steps people can take to reduce the amount of benzene to which they’re exposed:

  • Stay away from cigarette smoke. If you are a smoker, try to quit. Cigarette smoke is a major source of benzene exposure.
  • If you are exposed on the job, talk to your employer about process changes (such as replacing the benzene with another solvent or making sure the benzene source is properly enclosed) or by using personal protective equipment. If needed, the Occupational Safety & Health Administration (OSHA) can provide more information or make an inspection.
  • Try to limit gasoline fumes by pumping gas carefully and choosing gas stations with vapor recovery systems that capture the fumes. Avoid skin contact with gasoline, which contains benzene.
  • Finally, use common sense around any chemicals that might contain benzene, like solvents, paints, and art supplies. Minimize or avoid exposure to their fumes, especially in unventilated spaces.


Ted Gansler, MD, MBA, is director of medical content for the American Cancer Society’s National Home Office.

12 thoughts on “Is your car killing you with benzene?

  1. Really very good explanation for clarification of doubts that arise out of confusions in such situations. Thanks Dr. Ted.
    Today's society needs more people like you. Keep it up..!!

  2. My husband died in December of angiosarcoma. Sloan Kettering told us there are two causes of this rare disease. Radiation treatment for Brest cancer and working in the auto industry where car seats were produced. Has this been debunked?

  3. Hello? Who wrote this? The bogus scare email stated that the allowable level of Benzene is 50mg per square ft. – a measurement of area, not volume which is intrinsically wrong. Your article states "The National Institute for Occupational Safety and Health (NIOSH) has a limit for short-term (15 minute) workplace exposure (3.2 mg per cubic meter) and for average workday exposure ( 0.32 mg per cubic meter)." Then, amazingly your article states "So, the benzene level stated in the e-mail (recalculated as mg per cubic meter) as acceptable is between the NIOSH levels for short-term and daily exposure." So, just how did you recalculate a measurement of area to one of volume? Especially when the conversion produces a Benzene level per cubic meter that is 15 to 150 times lower than the level per square foot. Truly beyond sloppy.

  4. Hi, Beth and Michael, thank you for your comments. Dr. Gansler will have answers for you within the next week. Thanks for reading, for your comments, and for your patience.

  5. And by within a week, I meant today. From Dr. Gansler:

    To Chetan PATEL and Venkatramana Bhat… thanks so much for your support.

    To Beth Herr… I’m so sorry to hear of your husband’s passing from angiosarcoma. People with long-term exposure to elevated levels of vinyl chloride monomer (often through work in industries such as plastic manufacturing) have an increased risk for developing angiosarcoma of the liver, as well as some other health problems. Air in new cars can also have elevated levels of this chemical. For more information see
    Radiation therapy for breast cancer can increase the risk of angiosarcoma developing in the treated breast (after breast conserving treatment) or in the arm on the same side as a breast treated by radiation and/or surgical lymph node removal. For more information see

    To Michael Ritter… in reply to your questions about who wrote this article, I have to take credit and blame as the author. My instructions from the editors of this blog were to concentrate on practical information for the general public and to limit discussion of technical details.[EDITOR'S NOTE: This is to get to the heart of the subject without getting too "in the weeds" with dense jargon as this is a blog and most people only read for 2-3 minutes.] With this request in mind, I decided not to mention the issue of incorrect units for benzene concentration. I assumed that this was a typo on the part of whoever wrote the original myth e-mail. However, I appreciate your comment, which provides additional evidence that the original writer was not scientifically qualified and/or not very careful. In evaluating e-mails or web content of this nature, technical errors (such as the one you pointed out) are often a valuable clue that the claims may be incorrect. Thanks for raising this interesting point.

  6. An addendum from Dr. Gansler:

    To Michael Ritter… After more thoroughly considering your question, I realize that you were probably asking about the author of the myth e-mail (who remains anonymous) and not the author of the article responding to the myth (me). Also, I should have re-read my own article more carefully before replying; I actually had already addressed your concern about of units for concentration:
    "Fact: The standard way to report levels of chemicals in air is mass per volume (for example, mg per cubic meter or cubic foot), not mass per area (mg per square foot). Although this is a technical detail, it suggests that the authors of this e-mail may have limited knowledge of the basic scientific principles of this topic."

  7. It would seem to me that if the two studies were examined side by side, there would be two different cars used. Having been around cars for well over 50 years, I can vouch that some especially newer ones have a chemical smell in them when the doors are first opened. Perhaps the German study used a BMW and other studies used a Ford. Just a thought.

  8. Studies and research constantly pivot 180 degrees and change advice. Thanks for debunking the irrational fear associated with this original article. Be happy with your life everybody – whether you are living ultimate health or not. Be happy.

  9. It's amazing that someone would make an issue about benzene in cars when cigarettes have A LOT more benzene in them, not to mention many other carcinogens. People willingly start smoking and continue to do so for many years, despite them knowing the facts of the dangers of tobacco smoking, or of taking any other drugs for that matter. So, I agree with the statement near the end of this article, where it says to stay away from cigarettes.

  10. Dr Gansler thank you for your article.

    Unfortunately most studies cannot be trusted. I also find if concerning that authors write about issues that do not directly effect them so they have no first hand experience. That makes me skeptical about their findings.

    Perhaps benzene is not so toxic. However the auto industry is well aware that cars are full of toxic chemicals just about everywhere from fuel combustion, refrigerant, coolant, oil vapors, etc.

    For the past year I have been suffering from chronic headaches, dizziness, lung and throat irritation, chest tightness, persistent cough, burning sensation. This happens everytime I drive my car. All these are symptoms of chemical poisioning yet no one can diagnose nor help fix vehicle.

    There definitely are odorless toxic fumes that contaminate car cabin when vehicle is driven. They have nothing to do with the environment and everything to do with the toxic materials used to design and manufacture autos.

    To make matters worse there are no environmental labs nor health providers that can actually test you nor your cars. That means millions of people are exposed to toxins from driving everyday.

    Please help with any advice.

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