Now a team from the US and Belgium has estimated that the excess NOx emissions from the approximately 2.6 million cars in Germany containing these devices could have caused 1200 premature deaths in Europe, corresponding to 13,000 life-years lost and costs of 1.9 billion euros. And around 60% of the costs could occur outside Germany.

"In addition to quantifying the human health impact of the excess NOx emissions, this paper shows that there is a strong air-quality benefit that can be realized if these vehicles are recalled and repaired in a timely manner," Ray Speth of MIT, US, told environmentalresearchweb. "For instance, while the emissions that have already occurred are expected to result in 1200 premature deaths, there are an additional 2600 premature deaths that can be avoided if a recall that eliminates the excess emissions is completed by the end of 2017."

Nitrogen oxides (NO and NO2) can harm health by increasing concentrations of fine particulate matter (PM2.5). Fine particulate matter has been linked to early death due to cardiopulmonary disease and lung cancer.

"It takes time for NOx to get converted into particulates, at which point they could be 100 to 200 kilometres or further away from their source," said Steven Barrett of MIT in a press release. "[Pollution] doesn’t care about political boundaries; it just goes straight past. A car in Germany can easily have significant impacts in neighbouring countries, especially in densely populated areas such as the European continent."

Barrett and colleagues estimated that the excess NOx emissions could cause 500 premature deaths in Germany, 160 in Poland, 84 in France, 72 in the Czech Republic and 55 in Italy. Other European countries could also see premature deaths but in lower numbers.

"It’s important to remember that the flow of emissions goes both ways," said Speth. "There are VW Group vehicles being used in all of these neighbouring countries that are also generating excess emissions, some of which will end up reducing air quality in Germany. Our current study doesn't specifically address this balance of emissions and impacts, but it is certainly an important topic to consider when trying to understand how to reduce air-pollution impacts in particular regions."

The EA189 1.2, 1.6 and 2.0 litre engines that used defeat devices were installed in some cars from the Volkswagen Group’s Audi, Seat, Skoda and Volkswagen brands. On-road tests showed mean NOx emissions for these affected vehicles of 0.85 g per km; the European Euro 5 standard is 0.18 g per km. The team estimated that the affected vehicles travelled a total of 354 billion km between 2008 and 2015, potentially emitting 240 kilotonnes of NOx more than if they’d been emitting at Euro 5 standard levels.

To come up with the results, the team first created a map of excess NOx emissions arising from the use of the defeat devices in Germany. The GEOS-Chem chemistry-transport model helped predict any increase in population exposure to fine-particulate matter and ozone in the European Union, Switzerland and Norway. Finally, a set of concentration-response functions enabled the team to estimate potential mortality outcomes from this exposure.

"It ends up being about a one percent extra risk of dying early in a given year, per microgram per metre cubed of fine particles you’re exposed to," Barrett said. "Typically that means that someone who dies early from air pollution ends up dying about a decade early."

An earlier study by Barrett, Speth and colleagues estimated that the excess emissions of NOx from affected Volkswagen Group vehicles from 2008–2015 could cause 59 early deaths in the US, producing a social cost of around $450 m. The research was the first peer-reviewed study of the potential for premature mortality to result from the installation of the defeat devices.

At roughly 2.6 million, the number of affected Volkswagen Group cars sold in Germany was 440% higher than the 482,000 sold in the US. These German cars drove around 20% more km per year on average, according to the researchers, resulting in estimated excess emissions in Germany some 540% higher than those in the US. What’s more, each unit of NOx emitted in Europe could result in an estimated five times as many premature mortalities per capita as in the US, a difference the team ascribes to Europe’s greater population density and its atmospheric conditions. Europe’s high ammonia emissions and relatively low sulphur emissions make population-weighted PM2.5 levels more sensitive to NOx emissions than anywhere on Earth apart from eastern China.

Now the researchers plan further study of the health impact of emissions from diesel vehicles in Europe, where the Euro vehicle emissions standards first introduced in 1991 have not reduced air pollution as much as expected.

"It seems unlikely that Volkswagen is the only company with issues with excess emissions," said Barrett. "We don’t know if other manufacturers have these defeat devices, but there is already evidence that many other vehicles in practice emit more than the applicable test-stand limit value. So we’re trying to do this for all diesel vehicles."

Speth, Barrett and colleagues reported their findings in Environmental Research Letters (ERL).

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