Love that new-car smell? Not so fast …

Some people enjoy the "new-car smell" that greets them for the first few weeks of owning a shiny, new vehicle but it's not entirely benign if the folks who run HealthyStuff.org are to be believed.

The web site of the Washington, D.C.-based Ecology Center recently issued its fourth list of 10 best and 10 worst car interiors based on the presence of potentially toxic chemicals emitted by everything from car seats and carpets to shift knobs and arm rests.

They're most noticeable in that "new-car smell" but are also evident from the annoying film that shows up on the inside of a car's windshield throughout its life and invisibly deposited on the dust that accumulates in the cabin. The culprits are volatile organic compounds (VOCs), which have been linked to health problems from allergies to cancer.

Ecology Center Research Direct Jeff Gearhart says the non-profit group is not singling out cars as cesspits of VOCs. They're found in a huge variety of products inside homes and offices as well as automobiles.

It's just that we spend an average 90 minutes a day in our vehicles and the harsh environment of a car's interior, especially high temperatures when parked, can exacerbate release of toxic chemicals.

"What we found was the levels that show up in the dust and on the window films were five to 10 times higher than what research has shown you find in homes and offices," Gearhart said in an interview. "People spend 90 per cent of their time indoors. Cars are part of that pie. Any way we can reduce the overall size of the pie by reducing the individual components has a significant impact because of the levels of exposure we've talked about."

Related links:
10 most-toxic car interiors
10 least-toxic car interiors

The Ecology Center has tested about 900 vehicles since 2006. Its latest review covers more than 200 popular 2011-12 models. The non-destructive testing uses X-ray fluorescence spectroscopy to measure the known emissions of particular substances.

The tests look for levels of several chemicals but stress three major ones: Chlorine, present in polyvinyl chlorides (PVC) used in plastics, bromine, which shows up in many flame retardants, and lead.

The list includes a disclaimer that HealthyStuff ratings are meant as general information and "do not provide a measure of health risk or chemical exposure associated with any individual product, or any individual element or related chemical." In other words, they're not telling you "don't buy this car."

"We put that in there because we're very explicit about the limitations of the work we do," said Gearhart.

The center shares its results with automakers and meets with design execs and sustainability managers.

"They view our work as alternating between being very useful and being very annoying," said Gearhart but added officials in many companies have the goal of reducing the presence of toxic chemicals.

"The work that we do helps people support folks that are trying to get these issues addressed," he said, noting the center's testing shows notable declines, with some vehicle models entirely chlorine free, for instance.

Honda said it was pleased to have four models in the top 10 this year. Gearhart pointed out 83 per cent of its vehicles had PVC-free interiors, compared with zero just a few years ago. It pushed to find cost-effective substitutes.

"Over the past decade, Honda has taken a number of steps to reduce or remove chemicals of concern from our vehicles," said Marcos Frommer, American Honda's chief spokesman. "We voluntarily report these efforts in our annual North American Environmental Report."

Gearhart said his group tries to reach out to companies that do poorly to explain their testing approach and talk about finding safer substitutes for toxic chemicals.

A key factor is considering their use at the earliest design phase, not as an afterthought.

"If you try to do it at the end of the design process where you try and swap that's where you sometimes get into the cost issues," he said.

Automakers have already learned to do this when it comes to the recyclability of a vehicle's component parts, he pointed out.

While there are no North American standards, Nissan, which has one model in HealthyStuff's top 10 and one in the bottom, uses VOC standards set by Japan's Ministry of Health, Labour and Welfare. It's complied since 2007 but "we try to exceed and go beyond that," says Tim Franklin, Nissan Canada's senior manager of global product planning.

So should you add HealthyStuff's list to your vetting process when new-car shopping, along with performance, fuel economy and crash-test data?

It sure can't hurt to reduce your exposure. There are no specific government standards for car interiors but Health Canada spokeswoman Christelle Legault pointed out via email that the government is working to reduce VOC exposure in consumer products.

She wouldn't comment on HealthStuff's list, saying the department hadn't reviewed it.