The researchers calculated the effect on US public health of the alleged Volkswagen violations of the Clean Air Act.
Use of the cheat allows vehicles to emit up to 40 times more emissions than permitted by the Clean Air Act, say researchers at the Massachusetts Institute of Technology (MIT) and Harvard University, both in Cambridge, MA, who quantify the human health impacts and associated costs of the excess emissions in a paper published in the journal Environmental Research Letters.
The study follows the recent allegation by the US Environmental Protection Agency (EPA) that the Volkswagen Group of America violated the Clean Air Act by developing and installing emissions control system "defeat devices" in model year 2009-2015 vehicles with 2.0 liter diesel engines.
The defeat devices comprise software that is designed to switch on a vehicle's full emissions control system only when it senses that a test is in progress, and not under normal driving conditions.
The authors note that on-road emissions testing suggests that in-use NOx emissions for the vehicles concerned are a factor of 10 to 40 above the EPA standard.
NOx is shorthand for "oxides of nitrogen," or "nitrogen oxides," a group of highly reactive gases, including NO2, which the EPA uses as an indicator for NOx. NO2 forms quickly from emissions from cars, trucks, buses and other similarly powered equipment. It contributes to the formation of ground-level ozone and fine particle pollution, and is associated with a number of adverse effects on the respiratory system.
Timely recall can prevent 130 additional premature deaths
In the new study, the researchers took the amount of excess pollution, multiplied it by the number of affected vehicles sold in the US, and extrapolated it over population distributions and health risk factors across the nation.
They conclude that the result will have a significant impact on the public health of Americans. Around 60 people will die 10-20 years prematurely. They also note that 130 additional premature deaths may be prevented if all vehicles affected are recalled by the end of 2016.
Should the affected vehicles not be recalled in the US, say the authors, then the effect of the excess emissions, from when they started and in the future, will lead to the premature deaths of 140 people.
In their paper, the team also estimates other impacts of Volkswagen's excess emissions on public health. They suggest it will cause 31 cases of chronic bronchitis and 34 hospital admissions for respiratory and heart conditions.
There will also be about 120,000 total days affected by work absence and other reductions in activity, plus 210,000 total days where people will suffer respiratory symptoms.
$450 million health expenses and social costs
In money terms, these effects will total around $450 million in health expenses and social costs, say the authors, who also note that if all vehicles are recalled by the end of 2016, savings of $840 million in further health and social costs can be made.
Commenting on the impact of their findings, lead author Steven Barrett, an associate professor of aeronautics and astronautics at MIT, says he and his colleagues hope they will help regulators estimate the impact of Volkswagen's action:
"It seemed to be an important issue in which we could bring to bear impartial information to help quantify the human implications of the Volkswagen emissions issue. The main motivation is to inform the public and inform the developing regulatory situation."
For the calculations, the team estimated the average amount of use each vehicle would have over its lifetime, combined this with sales data to calculate the total emissions, based on an emissions level per vehicle of 40 times over that permitted by law.
They then examined three scenarios: the current one where over 480,000 diesel vehicles have already emitted excess levels; a scenario where every affected vehicle is recalled by the end of 2016; and a scenario where no vehicles are recalled and remain on the road emitting excess levels of pollutants over the remainder of their lifetimes.
Using methods that map emissions to public exposure to pollutants, the team then calculated the public health impact of each scenario. Prof. Barrett explains that excess emissions is one of the many health risk factors we face in our lives, and:
"If you take into account the additional risk due to the excess Volkswagen emissions, then roughly 60 people have died or will die early, and on average, a decade or more early."
Looking at the statistic by each kilometer driven, this number of deaths is about a fifth of those caused by traffic accidents, he adds.
Diesel emissions containing NOx are not only harmful to humans but also to wildlife. From another recently published study on the effect of diesel exhaust, Medical News Today learned that it can confuse honey bees' sense of smell to the extent that they fail to recognize half of the flower scents they use to find food. While this may not be the main reason for the decline in pollinator populations, it probably contributes to it, say the UK researchers.