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

A corporate logo of Volkswagen illuminated by the morning light at the plant of the German car manufacturer in Wolfsburg, Germany, last week.
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 to calculate the lives lost from excess pollution. 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 in 11 million diesel cars that deceived emissions tests, 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 the 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 be converted into ground-level ozone, or smog, and particle pollution, which also harm health.

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 worsen the suffering and risk for those with chronic conditions like asthma and chronic obstructive pulmonary disease, and drive up hospitalizations and premature deaths, particularly among older people.

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, 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 extra pollution was responsible for about five more deaths for every 100,000 people each year, as well as an increase in spending on prescription drugs. Most of the excess deaths came among older Americans, though other health impacts reached the young as well as the old.