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We bought a new car and the smell reminded me of something I was curious about: I remember reading somewhere that the smell of new car is actually the "smell of death" - that is, the smell of formaldehyde.

Here's an example of the claim:

Ahh, the "new car smell." Nothing else smells like it. Nothing except a mixture of volatile organic compounds ( VOCs) you wouldn't want in your drinking water or food (like the carcinogens formaldehyde and styrene).

Is this true?

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Is formaldehyde the sole source of the 'new car smell'? No.

It's more than likely the combined smell of the VOC's (of which formaldehyde is one) emitting from the interior, as there's over a dozen VOC's which are present.

Brown, Stephen K and Min Cheng, 2007. Volatile Organic Compounds (VOCs) in New Car Interiors

They found that the amount of VOCs present is dependent upon the 'delivery time' of the car from the manufacturer. Those cars which didn't have a 'shelf life' at a dealership had the highest amounts of VOCs present. Those which had been on display outside had the lowest.

The chemicals they recorded were:

  • acetone + n-pentane
  • n-Hexane + MEK (Methyl ethyl ketone)
  • Benzene
  • MIBK (methyl isobutyl ketone)
  • Toluene
  • m+p Xylene
  • Styrene + o-xylene
  • Ethylene glycol butyl ether
  • 1,2,4 trimethylbenzene
  • n-undecane
  • n-decane
  • 2-propylheptanol
  • n-dodecane
  • ethylbenzene
  • cyclohexanone
  • n-heptane

Of these chemicals, they ranked them from most prevalent to least as follows:

Overall, the more dominant VOCs found in the new cars (highest to lowest concentrations) were toluene, acetone/pentane, o-xylene/styrene, 1,2,4-trimethylbenzene, m,p-xylene, various C7–12 alkanes, ethylbenzene, n-hexane and ethylene glycol butyl ether.

They reported the following regarding the toxicity of the VOCs present:

Benzene is a category 1 IARC carcinogen (known human carcinogen) for which an annual exposure goal of 16 µg/m3 has been recommended (see Section 1.3). Since urban populations spend an average of one hour per day in car travel (Newton et al. 2000), these results indicate that car interiors can be contributors to total exposure to benzene.

Few environmental exposure goals are established for other VOCs. The NHMRC goal of 250 µg/m3 for any compound was exceeded for many VOCs in Cars 2 and 3. Toxic effects of some of these VOCs and ambient air goals (µg/m3 at 0oC/101kPa) based on these effects (Calabrese & Kenyon 1991) are:

  • acetone: mucosal irritation (8-hour goal, 39,000)
  • cyclohexanone: possible human carcinogen (annual goal, 180)
  • ethylbenzene: systemic toxin (24-hour goal, 140);
  • MIBK: systemic toxin (8-hour goal, 540)
  • n-hexane: neurotoxin (24-hour goal, 540);
  • styrene: probable human carcinogen (annual goal, 29)
  • toluene: central nervous system dysfunction (8-hour goal, 1600); xylene isomers: foetal development toxins (24-hour goals: o-xylene 310, m-xylene 3100, p-xylene 62).

It is seen that several of these goals may have been exceeded in the cars for several weeks after manufacture TVOC concentrations also occurred at levels that may affect occupants (see Section 1.2) for weeks to months after car purchase, although not for years. The effects that could be caused by this TVOC exposure include eye irritation, and performance and memory factors, all of which may be important car safety issues, as well as occupant health and comfort issues.

Note, however, that all of the above measurements were made in closed cars at low ambient temperatures. Lower concentrations may be expected with greater ventilation of the car interior, while higher concentrations may be expected under higher ambient temperatures. More detailed investigation of VOC concentrations under different operating conditions is needed to decide an appropriate test protocol for simulating occupant exposure to car interior pollutants.

They conclude the following:

High concentrations of VOCs were found in new cars, especially those reaching the market soon after manufacture, i.e with minimum path-to-market. The total VOC (TVOC) levels found have been observed previously to cause sensory irritation and performance and memory impairment to human subjects, showing that the pollution of new car interiors may be a safety issue. Several of the VOCs observed have potential toxic effects, an aspect that should be explored in further study under simulated conditions of car usage. The decay of TVOC concentrations was found to be exponential, at approximately 20% per week, with the NHMRC indoor air goal being reached after approximately 6 months.

So yes, that lovely smell you smell in your new car is a bunch of chemicals you really don't want to be smelling. And, if you live where it's warm - you'll smell more of them.

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    in other words air out your car before you use it – ratchet freak Aug 13 '11 at 15:21
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    Yep - but keep in mind that it can continue to emit VOC's for months. – Darwy Aug 13 '11 at 16:17
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    I predict that we're going to start seeing "organically cleaned new and used vehicles" being marketed in the near future. – Randolf Richardson Aug 14 '11 at 3:14
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    Another reason to buy used cars. – Moab Aug 17 '11 at 2:54
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    Great answer, I will refer many to it when they ask why I am now keeping a canary on my dashboard. – Monkey Tuesday Aug 18 '11 at 1:56

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