Researchers have measured harmful amounts of carcinogens in the air of a car cabin. The carcinogens may have been overlooked so far because they are not released quickly under the usual test conditions.
Carcinogenic substances are sometimes released in too high concentrations in new car cabins. This can entail health risks.
Researchers from China and the United States studied air quality in a new SUV that was left outside for twelve days. They measured the concentration of twenty substances in the air of the car cabin and recorded the conditions in the car, such as temperature and humidity. Temperature turned out to be the driving force behind the higher concentration of carcinogens such as formaldehyde and benzene.
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Climate chamber
Few studies have been done on air quality in cars, as opposed to those in other environments such as offices and classrooms. As a result, we know less about what goes on inside a car, while the Dutch spend an average of eight hours a week in the car.
In many countries it is mandatory to test new cars for air quality in the cabin first. This is to see whether the emission of toxic substances from the interior is not too high. Such a test is also mandatory in the EU to check how much formaldehyde is released from car upholstery.
Such a test is usually done in a so-called climate chamber at 23 degrees Celsius. These are not realistic conditions of use, say the researchers. For example, on a spring day of 21 degrees, a car in the sun can heat up to 45 degrees Celsius within an hour. The researchers suspected that the conditions that a new car actually encounters have an impact on air quality.
Operating condition
The researchers tried to simulate conditions of use during their research, by leaving the car outside for twelve days. The researchers also measured twenty carcinogenic substances that already start to evaporate at room temperature, so-called volatile substances. In the car cabin, these volatile substances are released from various materials, such as seat upholstery, paint and plastic. When the temperature in the car rises above room temperature, the substances evaporate even faster.
The researchers used their measurements to formulate better formulas for how many harmful substances are released from a car interior. These formulas showed that calculations without temperature information do not accurately predict how many harmful substances will be released. Temperature is currently not included in the calculations of most car manufacturers.
The measurements in the SUV showed that higher temperatures in particular lead to higher concentrations of toxic substances. For example, the maximum concentration of formaldehyde measured was twice as high as the maximum recommended concentration indicated by the World Health Organization (WHO). That concentration only occurred at an air temperature in the car of 63 degrees. However, the average concentration during the twelve days was below the WHO limit. The toxic substances benzene and ethanal were also found in relatively high concentrations, but these substances remained below the WHO limit.
Window open
Taking the concentrations of formaldehyde, benzene and ethanal together, 1 in 10,000 drivers who regularly drive in hot weather for 40 years will develop cancer, or an increased risk of cancer of 0.01 percent. “But,” says consumer safety expert Femke Affourtit of the RIVM, ‘with this risk assessment you will have to drive a new, warm car with the windows closed for 40 years, eleven hours a day, five days a week. That is not the case for the average consumer in the Netherlands.’
When the driver opens a window, the concentration of toxic substances drops significantly. With a window open, even when the car is stationary, the air in a car is refreshed more than six times an hour. The researchers therefore advise people to drive with their windows open, especially in hot weather.