Consumers are increasingly concerned about toxic chemicals that off-gas and leach from interior auto parts such as steering wheels, dashboards and seats. In addition to contributing to “new car smell,” these chemicals can be harmful when inhaled or ingested and may lead to severe health impacts such as birth defects, learning disabilities and cancer. Since the average American spends more than 1.5 hours in a car every day,1 toxic chemical exposure inside vehicles is becoming a major source of potential indoor air pollution. While the emphasis of this study is on the exposure to toxic chemicals during the use phase of vehicle life, our rating system also considers potential health and environmental impacts during the production of materials and end-of-life of vehicles. 

The good news is that some cars are better than others. Toxic chemicals are not required to make indoor auto parts, and some manufacturers have begun to phase them out. Scientists and researchers at the Ecology Center have created so that consumers can access information about the chemicals used in their car or the car they are thinking of purchasing. In addition to gas mileage and crash test ratings, car-buyers can now learn if the materials in their car are safe for themselves and their family. 


The average person spends about 5.5% of their time in automobiles during the work commute, recreation or other travel activities which makes it an important microenvironment for exposure to pollutants.2 The importance of this microenvironment has noted by the World Health Organization which has recognized interior air pollution of vehicles are a major threat to human health.3 The indoor air quality of an automobile is diminished from outdoor and traffic pollution, and compounds used in the interior materials and finishes of cars. These pollutants include such compounds as, polybrominated diphenylesthers (PBDEs) and other brominated flame retardants (BFRs), volatile organic compounds (VOCs), phthalate plasticizers, hydrocarbons and particulate matter.4 Among the common VOCs found in vehicles include benzene, ehtybenzene and styrene, all known or suspected carcinogens.7 Most exposure to these compounds is through ingestion of contaminated dust, and inhalation of dust, gases and vapors. All of these pollutants have been studied in detail and produce unique human health effects. 

everal studies have investigated the concentration of VOCs, BFRs and hydrocarbons in car interiors. Many of these pollutants, including benzene, toluene and xylene, were found in levels exceeding indoor and outdoor air quality standards and, for some BFRs, contribute nearly 30% to total daily exposure with average exposure levels of 396 pg/m3 and maximum concentrations of 2644 pg/m3.3,2 Total VOC concentrations were have been found at levels up to 3,656 ng/m3.7 

These compounds are present in the interior fabrics and materials of the car (coatings, trims, leather, etc.) as well as fuel combustion products from neighboring motorists. VOC concentrations decrease significantly over time as the compounds off-gas and are removed from the interior of the car.3 However, it has been shown that increased temperature of the car interior increases the concentration of VOCs and sunlight (UV) exposure reaction products which can also be harmful to human health.2,5 

Particulate matter, specifically with diameters less than 10 micrometers (PM10) and 2.5 micrometers (PM2.5) are primarily from fuel combustion on the roadways which then make their way into the interior of the car through open windows or heating/air conditioning units. Studies of automobile interiors have measured particulate concentrations exceeding US EPA standards, especially for drivers in heavy traffic situations.6 Average PM2.5 concentrations were 24 μg/m3 and average PM10 concentration was 21 μg/m3.4 

When compared to residential indoor air, in-vehicle VOC concentrations commonly exceed those found in residential settings and can 2-3 times higher then other modes of transportation.7,8 One recent study found VOC concentrations in car showrooms were 12-times higher than ambient concentrations outside of the showroom.4 


  • This report is releasing new test data on 204, 2011- 2012 model new vehicles. This data is part of a multi- year vehicle database containing test results for 900 vehicles.

  • The overall best and worst vehicles are listed below. The 2012 Honda Civic (score 0.46) was the overall best rated vehicle and 2011 Mitsubishi Outlander Sport (score 3.17) was the overall worst rated vehicle this year.

  • TheCivicachieveditsrankingbybeingfreeofbromine- base flame retardants is all interior components, utilizing PVC-free interior fabrics and interior trim, and low levels of heavy metals and other metal allergens

  • The Mitsubishi Outlander contained bromine and antimony-bases flame retardants in seating, the center console and seat base, chromium treated leather on several components and over 400 ppm lead in seating materials. Top Ranked Manufacturer:


  • The top-rated automaker for healthy interiors continues to be Honda. Honda has been’s top ranked automaker every year