Other top ranking cars this year are the Toyota Prius and the Honda CR-Z, with the Chrysler 200 SC and Kia Soul rounding out the bottom three.
The rankings found that overall vehicle ratings are improving, with 17 percent of new vehicles having interiors free from PVC, and 60 percent being free from brominated flame retardants.
Researchers at the non-profit tested more than 200 of the most popular 2011- and 2012-model vehicles for chemicals that off-gas from parts such as the steering wheel, dashboard, armrests and seats. These chemicals give vehicles that much-loved “new car smell,” but also contribute to a number of acute and chronic health problems, the center said.
Since the average American spends more than 1.5 hours in a car every day, exposure to the hundreds of toxic chemicals inside vehicles can be a major source of indoor air pollution. Their internal air temperatures of up to 192°F and dash temperatures of up to 248°F can increase the concentration of volatile organic compounds and break other chemicals down into more toxic substances, the center said.
Ecology Center research director Jeff Gearhart said that these chemicals are not regulated, so car buyers have no way of knowing what dangers they or their employees face.
Chemicals of primary concern include: bromine, chlorine, lead and heavy metals. Such chemicals have been linked to a wide range of health problems such as allergies, birth defects, impaired learning, liver toxicity, and cancer, the center said.
The Civic achieved its ranking by being free of bromine-based flame retardants in all interior components; using PVC-free interior fabrics and interior trim; and having low levels of heavy metals and other metal allergens.
The Mitsubishi Outlander contained bromine and antimony-based flame retardants in the seating and center console; chromium treated leather on several components; and over 400 parts per million of lead in seating materials, the Ecology Center said.
Fleet owners can visit the rankings page to search by model, comparison shop between different models, and cross reference with fuel economy standards to find both a healthy and fuel-efficient vehicle. A widget and mobile phone application are also available.
Gearhart said the Ecology Center is encouraging site visitors to ask automakers to subscribe to voluntary third party eco labels, such as the TUV Toxproof and Öko-Tex Standard 100. A number of manufacturers including Ford and Volvo, have already adopted these standards for some of their vehicles.
But Volvo was also one of just two automakers in the rankings that had overall declining average scores from 2009/10 to 2011/12. The other was Daimler.
The most improved automakers in terms of the average ratings for their vehicles were Volkswagen (+42 percent), Mitsubishi (+38 percent) and Ford (+30 percent).