In 2015, Volkswagen found itself the target of intense public ire — regulators had found that the German automaker had sold millions of cars worldwide that were falsely touted as “clean diesel.” The clean diesel cars were not clean at all. It turned out that Volkswagen had installed software that changed how the engine ran when it was undergoing an emissions test to make it look like a low-emissions vehicle.
The rest of the time? The cars were emitting dangerous pollutants at levels up to 150 times that of a normal car.
Volkswagen caught a lot of flack for that act of corporate perfidy, deservedly so. And in that act, two researchers saw an opportunity: Volkswagen’s deceitfulness created the conditions for a natural experiment on air pollution.
A new working paper, from Diane Alexander and Hannes Schwandt at the Federal Reserve Bank of Chicago and Northwestern University respectively, used the Volkswagen scandal to explore the health impacts of car companies’ cheating on emissions tests and what it can tell us about the high costs of pollution from cars.
Since 2009, Volkswagen sold 480,000 “clean diesel” cars in the US that were actually heavy polluters in disguise, and other cheating companies sold an additional 120,000. Those “cheating cars” were not evenly distributed around the United States; some areas had lots of the cheating cars, while others had only a few. That uneven distribution allowed the researchers to look at different measures of air quality and health, and to find correlations with the presence of polluting cars.
Alexander and Schwandt’s finding? “Counties with increasing shares of cheating diesel cars experienced large increases both in air pollution and in the share of infants born with poor birth outcomes,” they write.
The effect is pronounced enough that every single cheating car has a noticeable effect on measures of babies’ health: “for each additional cheating diesel car per 1,000 cars — approximately equivalent to a 10 percent cheating-induced increase in car exhaust — there is a 2.0 percent increase in air quality indices for fine particulate matter (PM2.5) and a 1.9 percent increase in the rate of low birth weight.”
While the effects are most pronounced for babies, there were impacts on children’s health as well: “we also find an 8.0 percent increase in asthma emergency department (ED) visits among young children for each additional cheating diesel car per 1,000 cars in a subsample of five states.”
Those are huge, alarming effects. And to be clear, Alexander and Schwandt’s paper has yet to be peer-reviewed. But their findings fit into an existing body of literature suggesting that air pollution is devastating, with enormous human health impacts we’re still just beginning to understand.
Researchers have found that adding E-ZPass to toll roads — which means that cars could drive through instead of idling to manually pay tolls — reduces premature birth rates in the area by an astounding 10 percent. Researchers have also found that when students move to schools with higher air pollution levels, their academic performance drops. The World Health Organization says that globally, more than one in four deaths of children under 5 are related to air pollution.
The more we learn about air pollution, the more it looks like a key global health priority.
What the Volkswagen study found, and what we still don’t know
This paper is still a working paper, so it has not yet been published in a peer-reviewed journal. And it makes some points that aren’t fully satisfying: For instance, the strikingly large asthma effect is only measured in five states due to “financial considerations,” but how were those five states chosen?
There are other questions as well. For one, diesel companies cheated in Europe, too, and diesel cars are far more common there, but Europe tends to have a much lower rate of premature births than the United States. A thorough look into this issue needs to account for that disparity — why isn’t air pollution having comparable effects there? Or, if it is, why are overall rates of premature birth still so much lower? (Lots of factors, including obesity, age of the mother, smoking, and access to prenatal care affect premature births.)
Another problem? The study assumes that we’ve now discovered all of the car companies that were cheating on emissions, but it seems possible — given how widespread the cheating was — that other, less egregious cheaters might still be active on the roads. (Later, it was revealed that other carmakers, including Audi, Porsche, and Fiat Chrysler, were cheating too, and they’re included in the study.) If there are more cheats out there, that wouldn’t necessarily invalidate the study’s conclusions, but if the cheating cars were less atypical than they look right now, the enormous effect sizes that the study observed would be fairly suspicious.
Overall, this is an intriguing piece of research that suggests the importance of additional research in this direction. But it’s only one piece of evidence, and not by itself enough to be confident of the enormous effect sizes it identifies.
That said, if this study holds up, it can have big policy implications. Most discussion of emissions and pollution lately has focused on carbon dioxide and climate impacts. This is a necessary reminder that fighting pollution isn’t just important because of the effects on the climate, it’s also about the immediate effects on our health and the health of our children. It might be easier to get the public to back strong emissions standards if there’s greater awareness that pollution won’t just affect our climate down the road — it can kill our children right now.
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