That distinctive “new car smell” – it’s a scent many find appealing, associating it with freshness and quality. For some, it’s even addictive. However, for others, this aroma can be unpleasant, especially for individuals with chemical sensitivities. But what exactly creates this unique smell, and is it something to be concerned about?
The reality, as chemists understand, is that new car smell is a complex cocktail of volatile organic compounds, or VOCs. These aren’t single chemicals, but rather a mixture of substances, predominantly alkanes, substituted benzenes, and smaller amounts of aldehydes and ketones. Almost every interior surface of a vehicle, from fabrics to plastics, is constructed using adhesives and sealants. The “new car smell” arises from the outgassing of residual solvents and chemicals from these materials, releasing VOCs into the car’s cabin. This phenomenon isn’t exclusive to cars; new airplanes, homes, and offices also exhibit similar outgassing.
Automakers typically monitor the total VOC emissions from interior textiles and flexible plastics to prevent window fogging. While each manufacturer has its own VOC standards, there are currently no overarching government regulations specifically addressing air quality inside new vehicles. Although individual VOC components are likely present in concentrations too low to be immediately harmful, the combined effect of long-term exposure to this VOC mixture is a question mark regarding potential health concerns. The good news is that VOC concentrations decrease significantly within the first few months after a car is manufactured. While VOC levels can spike in a closed car on a hot day, opening a door, lowering a window, or turning on the air conditioning rapidly improves air exchange.
Standard window fogging tests don’t provide detailed chemical breakdowns of the air in new cars. Popular belief, often echoed in media and online forums, attributes the pleasant aspect of new car smell primarily to phthalate plasticizers used in PVC and other plastics. However, bis(2-ethylhexyl) phthalate, a common PVC plasticizer, isn’t very volatile. Furthermore, available studies analyzing VOCs in new cars haven’t identified phthalates as major components in the overall VOC mixture.
A study conducted by Stephen K. Brown and Min Cheng at Australia’s Commonwealth Scientific & Industrial Research Organization (CSIRO) provides valuable insight. They analyzed air samples from three new 1998 vehicles using gas chromatography/mass spectrometry after the cars had been sealed for several hours. Follow-up samples were taken over two years.
The CSIRO study detected 30 to 40 different VOCs within these vehicles. The most prevalent compounds included toluene, acetone, xylenes, styrene, 1,2,4-trimethylbenzene, various C5 to C12 alkanes, ethylbenzene, and ethylene glycol butyl ether. Initial total VOC concentrations reached as high as 64 mg per cubic meter of air. An older imported car in the study, a few weeks post-manufacture, showed a significantly lower initial VOC level of 2.1 mg per cubic meter. These values fall into the parts-per-million to parts-per-billion range.
For context, the report noted that indoor air VOC levels in new buildings average between 20 to 40 mg per cubic meter, while established buildings typically have VOC levels below 1 mg per cubic meter. Negative health effects such as headaches, drowsiness, nausea, respiratory issues, and irritation of the eyes, nose, and throat are more likely to occur at VOC concentrations exceeding approximately 10 mg per cubic meter, according to the CSIRO report.
The study showed that total VOC concentrations in cars decrease exponentially over time, dropping to around 1.5 mg per cubic meter after six months. After two years, levels in two tested cars were around 0.4 mg per cubic meter. Outdoor air measured near the cars registered about 0.1 mg per cubic meter. 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 originate from the car’s interior materials. Benzene and other compounds from fuel or exhaust, as well as siloxanes from cleaning products, can also contribute to the total VOC load. CSIRO has considered developing a “green air label” to guide consumers toward vehicles, airplanes, offices, and homes with potentially healthier indoor air environments. Automakers are actively working to reduce the use of parts that emit high levels of VOCs.
Ironically, these efforts mean that some new cars today may not have a strong “new car smell” anymore. This has led to the rise of “new car scent” air fresheners designed to maintain that showroom aroma indefinitely. These products, commonly found at car washes and auto supply stores, aren’t required to list ingredients as they are classified as “household products”. Manufacturers contacted declined to disclose their proprietary formulas. Fragrance industry sources indicate these products typically contain a fragrance oil on a blotter card, in a gel, or diluted with water and/or alcohol. Simple fragrances may consist of aldehydes, esters, and ketones.
One of the earliest “new car smell” scents was actually the smell of treated leather. Natural tanned leather can have a slightly unpleasant odor, so tanneries often add artificial fragrances to create a fresher scent – reminiscent of the aroma in a shoe store. This concept was adopted by some automakers who have been known to add leather scents and other fragrances to vehicles.
Regardless of personal preference for the scent, if you’re health-conscious, the best approach is to ensure adequate ventilation by allowing outside air to circulate in your new vehicle, particularly for the first six months after purchase.
