The study, which was undertaken by the university’s assistant professor in civil and environmental engineering, Chris Cherry and graduate student Shuguang Ji, analysed emissions for five vehicle technologies in 34 Chinese cities and focused on dangerous particulate emissions.

Because China has a carbon-rich electrical grid, with 85% of electricity produced from fossil fuels and 90% of that volume produced using coal, electric cars were shown to have a much higher particulate emissions per kilometre than a petrol car.

This is despite the power stations in question being based rurally, where the particulates are breathed in at a lower rate than those from conventional cars, the report added.

Particulate emissions are proved to be far lower in countries with a large proportion of nuclear power stations – such as France. In the UK, a recent study by Imperial College London showed carbon emissions from electric vehicles charged during the day were, at worst, on a par with efficient diesels due to the higher use of fossil fuels in electricity generation at peak times. Night time charging greatly reduces the equivalent environmental impact.

‘The study emphasizes that electric vehicles are attractive if they are powered by a clean energy source,' Cherry explained. ‘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.’

China is an advanced nation in e-mobility, with electric vehicles outnumbering conventional counterparts 2:1. But while electric cars were shown to emit higher volumes of particulates per kilometre, the electric bikes which are popular forms of transport in China resulted in the lowest health impacts per kilometre travelled.

‘An implicit assumption has been that air quality and health impacts are lower for electric vehicles than for conventional vehicles. Our findings challenge that by comparing what is emitted by vehicle use to what people are actually exposed to. Prior studies have only examined environmental impacts by comparing emission factors or greenhouse gas emissions,' added Cherry.