美國田納西州立大學土木與環境工程系助理教授 Chris Cherry 以及他的研究生 Shuguang Ji 分析了中國34個主要城市中，五種不同交通工具的排放物對環境健康的影響，特別是危險的細懸浮微粒。
Electric vehicles in China cause more harmful particulate matter pollution than gasoline-fueled cars, when emissions from the generating stations that power them is factored in, new research shows.
In China, 85 percent of electricity production is from fossil fuels, and about 90 percent of that is from coal. The generation of electricity to operate EVs emits fine particles at a much higher rate than petrol-powered vehicles, finds a team of researchers from the United States and China.
Chris Cherry, assistant professor in civil and environmental engineering at the University of Tennessee, and graduate student Shuguang Ji, analyzed the emissions and environmental health impacts of five vehicle technologies in 34 major Chinese cities, focusing on dangerous fine particles.
"An implicit assumption has been that air quality and health impacts are lower for electric vehicles than for conventional vehicles," Cherry said.
"Our findings challenge that by comparing what is emitted by vehicle use to what people are actually exposed to," he said. "Prior studies have only examined environmental impacts by comparing emission factors or greenhouse gas emissions."
Electric vehicles in China outnumber conventional vehicles 2:1. E-bikes in China are the single largest adoption of alternative fuel vehicles in history, with over 100 million vehicles purchased in the past decade, more than all other countries combined.
For electric vehicles, says Cherry, combustion emissions occur where electricity to power them is generated rather than where the vehicle is used.
The researchers estimated health impacts in China using overall emission data and emission rates from literature for five vehicle types - gasoline and diesel cars, diesel buses, e-bikes and e-cars - and then calculated the proportion of emissions inhaled by the population.
The impact of electric cars was found to be lower than diesel cars but equal to diesel buses. E-bikes yielded the lowest environmental health impacts per passenger per kilometer.
The type of air pollution measured for the study - particulate matter - includes acids, organic chemicals, metals, and soil or dust particles. It is also generated through the combustion of fossil fuels.
Cherry said the research highlights the importance of considering exposures and the proximity of emissions to people when evaluating environmental health impacts for electric vehicles and the impact of moving air pollution out of cities. For electric vehicles, about half of the urban emissions are inhaled by rural populations, he said.