Air pollution in Europe costs more than £1.5trn a year-roughly equivalent to a tenth of the continent’s GDP, according to a 2015 study by the World Health Organisation. The study, covering EU and non-EU states, is the first attempt of its kind to calculate the monetary costs of polluted air. These costs come in the form of 600,000 premature deaths a year, as well as non-fatal illnesses. Overall, the study found that pollution is a factor in the deaths or illnesses of at least one in four Europeans; that air pollution is the single biggest environmental health risk; and that in 2012 outdoor pollution, such as that from diesel car exhausts, accounted for 482,000 premature deaths Europe-wide.

It depends on the type of pollution, but overall, road transport is the biggest single source of air pollution in cities. According to the World Atlas of Atmospheric Pollution (from 2011), road transport accounts for 88% of the carbon monoxide in London’s atmosphere, 62% of particulate matter, and 53% of nitrogen dioxides (NOx). London, like Milan and Stockholm, has tried to tackle this via congestion charging and a low-emissions zone, and from 2020 an “ultra-low-emissions zone” will be created, meaning all pre-2007 motorcycles, pre-2006 petrol cars and pre-2015 diesel cars will pay an extra £12.50 on top of the existing £11.50 a day rate. In Paris, meanwhile, new rules that come into effect next Friday (1 July) will ban pre-1997 cars and pre-1999 motorbikes from the streets on weekdays, in effect removing about 5% of polluting elements linked to cancers, heart disease and respiratory problems such as asthma.

All-electric cars (such as the Nissan Leaf and the forthcoming Tesla Model 3) and plug-in  hybrid vehicles ( like the Toyota Prius) are obviously less polluting. But sceptics say, you can’t just consider the car-you have to consider how its electricity is produced. Given that a significant proportion of electricity is produced by coal-driven power stations (the global proportion is 41%, according to the World Coal Association), it is to some extent true that, as the green venture capitalist  Vinod Khosla has noted, “electric cars are coal-powered”. Also, while electric cars emit less carbon dioxide, the production of their batteries creates vast quantities of the greenhouse gas, meaning that over an electric car’s lifetime the advantage is marginal. That’s before you get into particulate matter.

The car industry has to made eco-friendly cars much lighter. the lithiumion battery is the dominant electric-car technology, but it’s so chunky the car base needs to be built around it. It’s also flammable, adding to the complexity of integrating them into the design. A key challenge for policymakers is to focus not just on engines but on pollution overall. Either way, most analysts expect sales of hybrids, in the first instance, to rocket once the typical electric-only range exceeds 50 miles and prices fall to those of a similarly specified diesel or petrol model. In ten years’ time it’s entirely possible that breakthroughs in technology  will mean that-after a century of cars driven by pollution-heavy combustion engines-we’ll be driving very different machines and breathing more easily.