Diesel Pollutes More Than Lab Tests Detect

Because of testing inefficiencies, maintenance inadequacies and other factors, cars, trucks and buses worldwide emit 4.6 million tons more harmful nitrogen oxide (NOx) than standards allow.

Heavy-duty vehicles accounting for 76 percent of the total excess NOx emissions. Image credit: tasnimnews.com (CC BY 4.0)

A new study from University of Colorado Boulder shows these excess emissions alone lead to 38,000 premature deaths annually worldwide.

The research was conducted in partnership with the International Council on Clean Transportation, a Washington, D.C.-based nonprofit organization, and Environmental Health Analytics LLC.

The findings reveal major inconsistencies between what vehicles emit during testing and what they emit in the real world --a problem that's far more severe, said the researchers, than the incident in 2015, when federal regulators discovered Volkswagen had been fitting millions of new diesel cars with "defeat devices."

The devices sense when a vehicle is undergoing testing and reduce emissions to comply with government standards. Excess emissions from defeat devices have been linked to about 50 to 100 US deaths per year.

Researchers found that in 2015, diesel vehicles emitted 13.1 million tons of NOx, a chemical precursor to particulate matter and ozone. Exposure in humans can lead to heart disease, stroke, lung cancer and other health problems. Had the emissions met standards, the vehicles would have emitted closer to 8.6 million tons of NOx.

Heavy-duty vehicles, such as commercial trucks and buses, were by far the largest contributor worldwide, accounting for 76 percent of the total excess NOx emissions. (Tasnim News Agency)

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