That distinctive “new car smell” – it’s a scent that for many, evokes feelings of excitement, luxury, and the thrill of a fresh start. It’s often described as leathery, plasticky, and undeniably unique to a brand-new vehicle. For some, it’s a pleasant and even addictive aroma, an olfactory signal of a prized possession. However, for others, particularly those with chemical sensitivities, this same smell can be quite unpleasant, even headache-inducing.
Image alt: Scientist Stephen Brown setting up air quality monitoring equipment inside a new car to measure volatile organic compounds (VOCs), highlighting research into new car smell.
But what exactly creates this unmistakable new car smell? The answer, as chemists have discovered, lies in a complex cocktail of chemical compounds known as volatile organic compounds, or VOCs. These aren’t single substances but rather a diverse mixture, primarily composed of alkanes and substituted benzenes, along with smaller amounts of aldehydes and ketones.
The Science of New Car Smell: VOCs Explained
Virtually every interior surface of a car, from the dashboard to the seats and carpets, is made from materials like fabrics and plastics. These materials are often held together with adhesives and sealants. Many of these components contain residual solvents and other chemicals that, over time, undergo a process called “outgassing.” This outgassing releases VOCs into the cabin air, creating that characteristic new car smell. This phenomenon isn’t exclusive to cars; you can also observe it in new airplanes, newly built homes, and freshly furnished offices.
Automakers are aware of VOCs and their potential impact on vehicle interiors. A common industry standard is to minimize the total amount of VOCs emitted by textiles and flexible plastics to a level that prevents the recurring fogging of interior windows. While each car manufacturer may have its own internal VOC standards, there are currently no widespread government regulations specifically targeting air quality inside new vehicles.
What Chemicals Make Up New Car Smell?
While the specific composition of new car smell is complex and varies, research has identified key components. Initially, the pleasant aspect of the smell was often attributed to phthalate plasticizers, commonly used to make polyvinyl chloride (PVC) and other plastics more flexible. However, bis(2-ethylhexyl) phthalate, a frequently used phthalate in PVC, is not very volatile. Studies analyzing VOCs in new cars have not identified phthalates as primary contributors to the overall VOC mixture.
One notable study conducted by Stephen K. Brown and Min Cheng at Australia’s Commonwealth Scientific & Industrial Research Organization (CSIRO) provided valuable insights. They analyzed air samples from three new 1998 vehicles that had been sealed for several hours, using gas chromatography/mass spectrometry. The researchers identified between 30 and 40 different VOCs. The most prevalent compounds detected were toluene, acetone, xylenes, styrene, 1,2,4-trimethylbenzene, various alkanes (C5 to C12), ethylbenzene, and ethylene glycol butyl ether. Initially, the total VOC concentrations were as high as 64 milligrams per cubic meter of air (mg/m3). Interestingly, in one car that was a few weeks older due to import delays, the initial VOC level was significantly lower at 2.1 mg/m3. These concentrations are in the parts-per-million to parts-per-billion range.
For context, the CSIRO report compared these levels to indoor air quality in buildings. New buildings typically have total VOC levels between 20 to 40 mg/m3, while established buildings generally have levels below 1 mg/m3. The report also noted that negative sensory effects, such as headaches, drowsiness, nausea, respiratory distress, and eye, nose, and throat irritation, are more likely to occur at VOC concentrations exceeding approximately 10 mg/m3.
Is New Car Smell Harmful? Potential Health Effects
While individual VOCs in new car smell are likely present in concentrations too low to be acutely harmful, the long-term effects of cumulative exposure to the complex mixture are less clear. Fortunately, the concentration of these compounds decreases significantly within the first few months after a car is manufactured. Although VOC levels can reach potentially unhealthy concentrations in a closed car on a hot day, the air exchange rate in a vehicle is relatively high when doors or windows are opened, or when the air conditioning is turned on.
The CSIRO study also tracked the decline of VOCs over time. They found that total VOC concentrations decreased exponentially, reaching approximately 1.5 mg/m3 after six months. After two years, the levels in two cars tested were around 0.4 mg/m3. Outdoor air measured near the cars had a VOC level of about 0.1 mg/m3. Temperature also plays a role; as the temperature inside a car increases, so does the total VOC concentration.
It’s important to note that not all VOCs detected in car interiors originate from the car’s materials. Benzene and other compounds from fuel or exhaust, as well as siloxanes from cleaning products, can also contribute to the total VOC load.
The Irony of New Car Smell Air Fresheners
Recognizing the potential health concerns and consumer demand for improved air quality, automakers are actively working to reduce VOC emissions from vehicle components. This effort has led to an interesting outcome: some newer cars simply don’t have a pronounced “new car smell” anymore.
This, however, has created a peculiar twist. A whole industry of “new car scent” air fresheners has emerged, designed to artificially recreate and prolong this very smell that automakers are trying to eliminate. These products, widely available at car washes and automotive supply stores, are often sold as “household products” and are not required to list their ingredients on the label. Manufacturers contacted for information about their composition have been reluctant to disclose proprietary details.
Fragrance industry experts indicate that these air fresheners typically contain a small amount of fragrance oil applied to a blotter card, incorporated into a gel, or diluted with water and/or alcohol. Simpler fragrances may contain just a few ingredients, often aldehydes, esters, and ketones.
One of the earliest artificial scents developed for cars was the smell of treated leather. Natural tanned leather can have a slightly unpleasant odor, so tanneries began adding artificial fragrances to leather to create a fresher scent. This leather scent concept was adopted by some automakers, who have been known to add leather and other fragrances to car interiors.
Conclusion
The “new car smell,” while often enjoyed, is essentially the aroma of various volatile organic compounds outgassing from the materials inside a vehicle. While concentrations are generally low and dissipate over time, understanding the source and composition of this smell provides valuable insight into the chemistry of our everyday environments. For those concerned about potential health effects, particularly in the initial months of ownership, ensuring good ventilation by opening windows or using the car’s ventilation system is advisable. Ultimately, whether you love it or dislike it, the new car smell is a fleeting chemical phenomenon, now ironically immortalized in air fresheners designed to mimic what is increasingly becoming a scent of the past.
