The use of electric cars in China produces more particulate matter pollution than gasoline-fueled vehicles, according to a new study.

In an analysis of five vehicle technologies in 34 major Chinese cities, U.S. researchers found that the power generated to run electric vehicles produces significantly greater particulate matter emissions because 80 percent of China's electricity comes from coal-burning power plants. While those plants are typically located far from population centers, the researchers nevertheless found that the difference in pollution is so great that electric vehicles are still more harmful to the public health per-kilometer traveled than conventional vehicles.

The study, published in the journal Environmental Science and Technology, emphasizes that electric vehicles are a cleaner option if powered by a clean energy source.

"In China and elsewhere, it is important to focus on deploying electric vehicles in cities with cleaner electricity generation and focusing on improving emissions controls in higher polluting power sectors," said Chris Cherry, a researcher at the University of Tennessee, Knoxville, and lead author of the study.