How Many Deaths Did Volkswagen's Deception Cause in the U.S.?

Volkswagen’s diesel deception unleashed tons of extra pollutants in the United States, pollutants that can harm human health. So while many commentators have been quick to say that the cheating engines are not a highway safety concern, safety — as in health — is still an issue.

Unlike the ignition defect in General Motors vehicles that caused at least 124 people to die in car crashes, Volkswagen pollution is harder to link to individual deaths. But it is clear to public health researchers that the air pollutants the cars illegally emitted damage health, and they have formulas for the number of lives lost from excess pollution in general. Indeed, the Environmental Protection Agency uses its own estimates of the health effects of air pollution to create its regulations of what’s allowed. After consulting with several experts in modeling the health effects of air pollutants, we calculated a death toll in the United States that, at its upper range, isn’t far off from that caused by the G.M. defect.

Volkswagen said last week that it had installed software that deceived emissions tests in 11 million diesel cars, allowing the vehicles to emit far more pollutants than regulations allowed. Our estimates examine only the impact on public health in the United States, but it’s clear the negative effects were probably substantially higher in Europe, where the cars are much more common.

The chemicals that spewed illegally from the Volkswagen diesel cars — known as nitrogen oxides or NOx — have been linked to a host of respiratory and cardiovascular illnesses, as well as premature deaths. Nitrogen oxides are a byproduct of burning fossil fuels at high temperature, whether in cars, power plants or other machines like industrial boilers. The chemicals can be harmful to humans, and in warm, sunny conditions, they can also turn into ground-level ozone, or smog, and unhealthy particle pollution.

Nitrogen dioxide and ozone irritate the lungs, increasing airway inflammation, coughing and wheezing, and can lower resistance to respiratory illness like influenza, especially with long-term exposure. The chemicals can also worsen the suffering and risk of serious illness or premature death for those with conditions like asthma and chronic obstructive pulmonary disease. Older people, who are more likely to have these ailments, are particularly vulnerable.

The impact of smog and soot pollution on global health is substantial: A recent paper by Jos Lelieveld, at the Max Planck Institute for Chemistry in Germany, and colleagues estimated that air pollution causes some three million premature deaths a year, and that the number of deaths could more than double by 2050.

The American Lung Association estimates that nearly 41 percent of Americans live in areas with unhealthy levels of ozone. And that’s with reductions brought about by national air quality standards and regulation. Between 1980 and 2014, the E.P.A. estimates that nitrogen dioxide levels in the air fell by more than half. The Obama administration has stepped up its regulation of emissions from power plants and tightened standards for vehicles. A still tougher ozone standard is expected next month.

The part of the country that has probably experienced the most harm from the Volkswagen fraud is California, which already has the worst air quality in the nation. About 7,200 premature deaths a year are caused by air pollution there, according to the California Air Resources Board, and 73 percent of the state’s population, or 28 million people, live in counties with unhealthy levels of ozone or particle pollution.

California also has the largest number of diesel passenger cars — some 50,000 of them, said Dave Clegern, a spokesman for the state’s air resources board, which regulates air quality in the state. Regulation has helped, Mr. Clegern said, but “we still have a significant problem.” Regulations are developed with automakers at the table, he said, and “in order to do that, you have to have a level of trust.” Regarding the Volkswagen deception, he said, “This kind of thing is, to say the least, absolutely no help.”

The potential damage of technologies like the “defeat device” that allowed Volkswagen to evade pollution rules since late 2008 is substantial. Volkswagen diesel cars represent fewer than 1 percent of cars on the road in the United States. But if every car — gasoline, diesel and electric hybrid — exceeded the legal limits by a similar amount, the consequences for air pollution and human health would be significant.

“Beijing comes to mind,” said Paul Billings, a senior vice president at the American Lung Association.

To estimate the harm in the United States, we used two different scientific models for the effects of nitrogen oxide pollution on human health.

One comes from a sort of natural experiment, when new regulations on power plant pollution caused some counties, but not others, to cut back on nitrogen oxide pollution. The counties subject to regulation reduced their nitrogen oxides emissions by 350 tons a year.

A team of three researchers — Olivier Deschenes, Joseph S. Shapiro and Michael Greenstone — looked at the mortality rates and medical spending before and after the change. In a working paper, they found the reduced pollution was responsible for about five fewer deaths for every 100,000 people in the affected counties each year, as well as for a decrease in spending on prescription drugs. Most of the seemingly excess deaths in the higher pollution regions occurred among older Americans, though other health issues affected the young as well as the old.

The estimated Volkswagen pollution, about 46,000 tons since late 2008, is the equivalent of about 4 percent of the power plant pollution reduction they measured, meaning it could be expected to cause an estimated 106 deaths if it had similar effects.

We ran this projection by Mr. Greenstone, a professor of economics and director of the Energy Policy Institute at the University of Chicago, and a contributor to The Upshot. He said it seemed sensible as an estimate, but “the magnifying glass is really close.”

Noelle Eckley Selin, an associate professor of earth, atmospheric and planetary sciences at M.I.T., ran the numbers a slightly different way. She looked at the mortality effects of the particulate pollution produced by nitrogen oxides, using the numbers the Environmental Protection Agency uses to make health estimates. Her method brought the effects to about 40 additional deaths over the period, in addition to some other nonfatal health consequences. That probably undercounts the impact, though, since it does not consider the effects of direct nitrogen oxide pollution or smog.

Now for all the caveats. Our estimates for the amount of nitrogen oxide pollution are back-of-the-envelope. We relied on data from Kelley Blue Book on the number of Volkswagen diesel cars registered each year, and we applied a standard number of miles driven by each car, based on a government average, to arrive at a total number of vehicle-miles traveled.

The E.P.A. has said that the vehicles emitted up to 40 times the legal limit of nitrogen oxides. But earlier research suggests that the pollution levels ranged widely among the vehicles and their driving conditions. We looked at 39 times the legal standard, but that may be a high assumption. (If you want to estimate the effects for emissions at, say, 29 times the legal limit, you can adjust our numbers down accordingly.)

Because smog is worse in the summer, Mr. Greenstone recommended that we look at pollution from five months each year. Ms. Selin’s approach was based on year-round pollution levels.

Of course, modeling the health effects of tailpipe emissions is more complicated than the sort of straight multiplication we have employed in both methods. The harm from nitrogen oxide pollution depends on how close people are to roads, as well as on topography and weather patterns. People who live in large cities, or near major roads, tend to experience disproportionate harm. Other news organizations, including Vox and The Guardian, have calculated slightly different estimates of the amount of pollution and the resulting harm.

Don Anair, deputy director of the vehicles program at the Union of Concerned Scientists, said the precise effect of the Volkswagen fraud would require intense and complex computation.

Still, he cautioned against taking the view that the Volkswagens have reversed the progress with pollution from automobiles. Since the standards went into effect from 2004 to 2009, he said, emissions of nitrogen oxides have been 90 percent lower. “It’s not like this is going to offset the majority of the benefits of these standards,” he said. “But there will be some impact, and we need to get a better handle on it.”

You can return to the main Market News page, or press the Back button on your browser.