After Being Parked in Direct Sunlight, Does Opening Car Windows Help Reduce Toxicity?

Explainer Health Hoax

Nowadays, people are more health-conscious and pay closer attention to ways to improve their well-being. But unfortunately, some misleading information sometimes gets shared, albeit in good faith.

Recently, viral social media posts claimed that automobile components emit dangerous levels of cancer-causing benzene fumes while parked under the hot sun for a few hours, hence advising users to open their windows for a while for these gases to flow out. However, while opening the vehicle windows briefly would help release heat from inside and reduce exposure to germs, there is no scientific evidence to suggest that this practice is done to wade off the dangerous gasses trapped inside the car.

Social Media Claims

The warning message circulating online warns people not to turn on their car’s air conditioning immediately upon entering the vehicle. The message states the reasoning behind this is that car dashboards, sofas, and air fresheners emit Benzene. In addition, the posts indicate that this toxin can also poison your bones, cause anemia, and reduce white blood cells. Furthermore, prolonged exposure to Benzene could cause leukemia, increasing the risk of cancer.

The posts also state that the acceptable level of Benzene indoors is 50 mg per sq. ft. and that a car parked indoors with closed windows will contain 400-800 mg of Benzene. However, if parked outdoors under the sun at a temperature above 60 degrees Fahrenheit, the benzene level goes up to 2000-4000 mg, 40 times the acceptable level.

The entire message can be seen below.

Source | Archive

Explanation from Specialized Expert

Asst. Prof. Dr. Pranut Photiyarat, the Director of the Metallurgy and Materials Science Research Institute (MMRI), explained to the Sure and Share channel that opening car windows could help release heat inside the car. This is because volatile substances from the production process may remain inside the vehicle. Still, these substances are usually present in very small amounts in the materials. 

Also, not turning on the air conditioner immediately allows fresh air from outside to enter and may help reduce dust; if the air conditioner is turned on immediately, the driver might be exposed to accumulated germs while the air conditioner is turned off.

Regarding the claim that toxic substances will be released from plastic equipment in the car, Dr. Pranut explained that older car models usually used plastic or PVC, which was found to emit small molecules. However, this practice has been discontinued. In more recent car models, the plastic used in the cabin is safer. Complete the video discussion in Thai here.

No Evidence to Suggest Cancer-Causing Levels of Benzene in Cars Exposed to Direct Sun Light

According to Snope, while there is evidence linking Benzene to cancer, the claim that automobiles produce potentially cancer-causing levels of Benzene has not been proven. The 2001 Korean study found that traveling by car increased exposure to several harmful compounds, including Benzene.

Still, the primary factor in this regard was the fuel used by the vehicles, not internal components such as dashboards. Additionally, the study found that benzene levels were higher in older cars than newer cars, which suggests that the primary factor in automobile benzene levels was not associated with the “new car smell” emitted by components such as dashboards and upholstery. Finally, the study also found that exposure levels were significantly higher during the winter months, which suggests that automobile air conditioning use is not a significant factor in benzene exposure.

The German study, conducted in 2007, specifically tested the health effects of emissions from one new and one three-year-old vehicle exposed to “parked in sunshine” conditions. It also found no apparent health hazard in parked motor vehicles’ indoor air. The scientists collected molecules from the air inside a new car and a three-year-old vehicle of the same brand placed under 14,000 watts of light, where temperatures reached 150 degrees Fahrenheit. They next exposed these compounds to human, mouse, and hamster cells grown in lab dishes. These are commonly used to test toxicity. New car smell does not appear to be toxic, the scientists found. However, air from the new car did cause a slight aggravation of the immune response that could affect people with allergies. Still, the same was not seen with the older vehicle.

Furthermore, the American Cancer Society has confirmed to WUSA9 that the viral warning about the danger of Benzene in cars has been circulating since 2011. However, studies show that Benzene can only lead to forms of cancer like leukemia after long-term exposure to the toxin, such as from cigarette smoke, gas stations, or working in a chemical plant. 

And to avoid or limit your exposure to Benzene, follow these guidelines:

  • Avoid cigarette smoke.
  • Avoid exposure to fumes and fuel mist.
  • Stay away from running cars.
  • Try to reduce exposure to chemicals containing Benzene.

(Red more about Benzene here)

Moreover, the American Chemical Society and the National Library of Medicine have researched the toxicity of parked vehicles. They have concluded that the air inside cars is not hazardous to human health and that high levels of Benzene are not emitted, as claimed by the viral warning.

Yet, the warning that one should open the windows and door to allow the interior to air out before one enters still stands. However, the reason has nothing to do with benzene levels. When a car is parked in the sun with its windows rolled up, that condition can create a greenhouse effect that causes the interior to warm to a temperature considerably higher than the outside air. Opening the windows for a few moments allows for exchanging hot air from inside the vehicle with cooler air outside, speeding up the cooling-off process.


No evidence supports the claims that automobile components emit dangerous levels of cancer-causing benzene fumes. While Benzene has been linked to cancer, the primary factor in automobile benzene levels is the fuel used by the vehicle, not internal components such as dashboards. Therefore, drivers can continue to use their air conditioning systems safely.

Still, opening the windows for a few moments is recommended to exchange hot air from inside the vehicle with cooler air outside, which can speed up the cooling off.


Title:Does opening car windows help reduce toxicity?

By: Fact Crescendo Team 

Result: Explainer

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