Over the course of seven years, Volkswagen and its affiliated companies sold millions of diesel vehicles around the world — nearly 500,000 in the U.S. — with emissions control systems rigged so that the cars falsely appeared to meet environmental standards. While much of the focus has been on the carmaker’s alleged fraud and the financial cost to consumers and VW, some researchers have been trying to figure out how many people died as a result of the additional toxic emissions released into the air.

The Associated Press took a shot at estimating the possible death toll for just the U.S. and arrived at a figure of between five and 20 deaths per year. In total, the AP concluded that anywhere from 16 to 94 additional people died in America during the last seven years because of VW’s deception software.

According to the EPA, affected VW vehicles released between 10 to 40 times the legally allowed amount of NOx (nitrogen oxides) into the air. NOx helps to form smog, which contains soot particles that kill upwards of 50,000 people a year in the U.S.

“Even the small increase in NOx from VW diesel emissions is likely to have worsened pollution along the roadways where they have traveled, and affected the lives of hundreds of thousands of people,” explains Dan Greenbaum, president of the Health Effects Institute in Boston, a group funded by both the EPA and the car industry. “To say millions of people of people are breathing poor air as the result of that is not off the mark.”

To arrive at its estimated death toll, the AP figured in existing pollution levels, along with the sales and use of the rigged VW cars. They also utilized computer models for air movement and previous studies on the epidemiological health effects of pollutants. That gave the AP its rough estimate of 5-20 deaths per year.

The news organization says it took the results to independent researchers who are not involved with either environmental advocacy groups or the auto industry and that these scientists “confirmed the calculations and results seemed right.”

One scientist the AP contacted claimed to have performed his own analysis and reached the same conclusion.

A calculation using the AP’s open source modeling system came up with a slightly lower death toll for the seven-year period: between 12 and 69 deaths.

Researchers acknowledge that it’s difficult to come to any hard-and-fast conclusion on the issue, as a number of assumptions need to be made about the effect of a handful of cars on the environment of a massive geographical area.

And unlike the General Motors ignition recall, where more than 100 fatalities have been definitively linked to the long-ignored problem, there’s no way to say “These particular people died because of VW’s emissions cheat.”

“Statistically, we can’t point out who died because of this policy, but some people have died or likely died as a result of this,” explains Carnegie Mellon environmental engineering professor Peter Adams, whose modeling system was used by the AP.

That model uses what the AP describes as “conservative” medical studies for its assumptions, and points out that other models would come out with twice the total fatalities.

The deaths are almost certainly higher in Europe, with its higher population density. Additionally, the vast majority of rigged vehicles were sold there.

One scientist tells the AP that the number of people who died because of the polluting VWs in Europe could be in the hundreds.

For its part, VW is attempting to minimize the significance of these numbers, pointing out that the EPA has said the cars are currently safe to drive.

“General allegations regarding links between NOx emissions from these affected vehicles and specific health effects are unverified,” reads a statement from the carmaker. “We have received no confirmed reports that the emissions from such vehicles caused any actual health problem.”

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