Researchers have found that diesel vehicle emissions are significantly underestimated in the real-world by as much as 50 percent. The research, led by the International Council on Clean Transportation and Environmental Health Analytics, tested the nitrogen oxide emissions from 11 major vehicle markets representing more than 80 percent of new diesel vehicle sales in 2015.
The study, published in Nature, found that of the 11 markets, the vehicles emitted 13.2 million tons of nitrogen oxide under real-world driving conditions. This results in 4.6 million tons more than the 8.6 million tons expected from vehicle performance under official laboratory tests.
Chris Malley, who was part of the study from the SEI, University of York, said in a statement:
“This study shows that excess diesel nitrogen oxide emissions effect crop yields and a variety of human health issues. We estimate that implementing Next Generation standards could reduce crop production loss by 1-2 percent for Chinese wheat, Chinese maize, and Brazilian soy, and result in an additional four million tonnes of crop production globally.”
A major contributor to outdoor air pollution is nitrogen oxide, and long-term exposure to these pollutants has been linked to many adverse health outcomes. These outcomes include disability and reduced life expectancy due to stroke, chronic obstructive pulmonary disease, heart disease, and lung cancer.
Josh Miller, researcher at the International Council on Clean Transportation (ICCT), said that is was heavy-duty vehicles that were the largest contributor:
“Heavy-duty vehicles, such as commercial trucks and buses, were by far the largest contributor worldwide, accounting for 76 percent of the total excess gas emissions.
“Five of the 11 markets that we looked at, Brazil, China, the EU, India, and the US, produced 90 percent of that.
“For light-duty vehicles, such as passenger cars, trucks, and vans, the European Union produced nearly 70 percent of the excess diesel nitrogen oxide emissions.”
The study authors estimated that the excess of diesel vehicle NOx emissions in 2015 was linked to approximately 38,000 premature deaths worldwide. The deaths were mostly from the European Union, China, and India.
Susan Anenberg, co-founder of Environmental Health Analytics, LLC, explained that:
“The consequences of excess diesel NOx emissions for public health are striking. In Europe, the ozone mortality burden each year would be 10 percent lower if diesel vehicle nitrogen oxide emissions were in line with certification limits.”
The study also estimates that unless something is done to reduce it, the impact of all real-world diesel nitrogen oxide emissions will grow to 183,600 early deaths in 2040 globally. According to the researchers, by implementing the most stringent standards, it could substantially improve the situation.
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