So how big of a deal is the Volkswagen cheating scandal? In terms of human lives cut short, 60 in the US alone, according a new peer-reviewed study in the journal Environmental Research Letters.
The study's conclusions are in line with back-of-the-envelope calculations from the New York Times, Vox, and other news organizations when the news of VW's emissions cheating first broke last month. What's different, though, is that these MIT and Harvard scientists had a fancy pants computer model. And their calculations could carry some weight as VW faces fines and a criminal investigation into the software that allowed its diesel cars to pass emissions tests while emitting up to 40 times the legal limit of nitrogen oxides (NOx).
When Steven Barrett, an emissions researcher at MIT, heard about the cheating, he immediately thought it was a perfect use for the model he had been developing with colleagues for the last five years. Its name is, as these technical things tend to be, a mouthful: GEOS-Chem adjoint-based rapid air pollution exposure model. Instead of taking the number of affected VW vehicles and multiplying some factors to get an estimated number of premature deaths, the GEOS-Chem model allows scientists to estimate the impact of extra NOx in any 50 km by 50 km square of the world.
Specifically, it takes into account the population in a given area and the local climate. NOx interacts with chemicals in the atmosphere to form particulate matter and smog—a process that depends on sunlight and temperature. Those particles are the actual nasty stuff that cause lung and heart disease and, eventually, death. According to the model, the extra NOx from VW's cars will cause about 10 to 150 (or a median of 59) people to die 10 to 20 years early. Hospital bills and other social costs add up to $450 million.
The study went from conception to publishing in a month—lightning fast by academic standards. And GEOS-Chem is a big part of that. Taking into account all those variables would have taken weeks using an old algorithm that also calculated a lot of irrelevant information, says Barrett. The team had developed GEOS-Chem as a way to provide "rapid response" to evolving policy conversations.
Whether this study will have an effect on VW remains to be seen. "The exact amount of the excess NOx emissions and the location of these emissions from the VW vehicles with the defeat device is a part of our ongoing investigation," said an EPA spokesperson, "so we can’t provide specific estimates at this time." VW did not immediately respond to a request for comment.
The authors are now beginning to analyze the impact of VW's emissions cheating in Europe—where diesel cars are even more abundant.
