The 2012 Honda Civic is the best-performing vehicle this year in terms of inside air quality, according to the 2012 consumer guide to toxic chemicals in cars jointly released by the HealthyStuff website and the Ecology Center, a U.S.-based nonprofit environmental organization.

The consumer guide, the fourth of its edition, is based on the Ecology Center's tests on more than 200 of the most popular 2011/2012 model vehicles for chemicals released from such parts as the steering wheel, dashboard, armrests and seats. These chemicals are the culprit of the interior air pollution which is as great a concern as outdoor air pollution.

According to the report, chemicals of primary concern include bromine (associated with brominated flame retardants), chlorine (indicating the presence of polyvinyl chloride, or PVC and plasticizers), lead and heavy metals. Many of the chemicals can cause a variety of health problems including allergies, birth defects, impaired learning, liver toxicity and cancer.

The report says that the overall ratings are improving, though. To date, the best vehicles have eliminated hazardous flame retardants and PVC. 17 percent of the new vehicles have PVC-free interiors and 60 percent are produced without BFRs.

Also read: Top 10 most toxic cars 2012

Following are the top ten model vehicles which have least health concerns from inside air pollution:

   2011 Smart Passion Cabriolet （2011款奔馳斯瑪特Passion Cabriolet）

 Overall Score: 0.79

 Chemical Level: Low

Bromine: 0.4        Chlorine: 0.0         Lead: 0.5         Others: 1.6

Class: Convertible

Manufacturer: Smart