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The Institute for the Environment will continue to study air quality impacts from commercial aircraft emissions with extended funding from the Federal Aviation Administration (FAA). This grant provides $424,988 for the next year and charges IE to use its sophisticated air quality models to identify thresholds for various pollutants and inform policy decisions to achieve the national ambient air quality standards. IE has been involved in this project for the last 3 years as part of a large, multi-institutional effort.

“Every year, we peel back a layer of the puzzle in terms of understanding how aircraft emissions impact the surface air quality,” says Sarav Arunachalam, a research associate professor at the Institute and principal investigator for the study. “We think we can really understand aircraft emissions to the point that we are able to make recommendations to the FAA in terms of what kind of air quality benefits are feasible given changes in emissions.”

UNC-Chapel Hill is one of 16 member institutions of ASCENT – the Aviation Sustainability Center –co-led by Washington State University and the Massachusetts Institute of Technology. ASCENT is a center of excellence for alternative jet fuels and environment and is funded by the FAA, NASA, the Department of Defense, Transport Canada and the Environmental Protection Agency. This consortium works to develop science-based solutions for all environmental impacts faced by the aviation industry and spans diverse disciplines from operations to emissions to environmental impacts and sustainability.

“We have made a large contribution to the scientific literature in terms of understanding what scales are important in aircraft emissions and how they affect air quality and human health,” says Arunachalam.

Arunachalam and his team have developed multiple tools and models, including sophisticated applications of the Community Multi-scale Air Quality Modeling System (CMAQ), that can be manipulated to isolate specific pollutants and adjusted in the models to compute and quantify pollutant concentrations due to aircraft emissions. These models help air quality managers determine the best air quality management scenarios.

Arunachalam says their work is moving toward studying alternative sources of jet fuel and examining the air quality benefits of using alternative fuels and more efficient technology for combustion in the aircraft engines.

“Air pollution from aircraft is a function of two aspects,” he says. “One is the kind of technology aircraft use in the combustion. The second is the type of fuel they use. FAA has an aspirational goal to replace a billion gallons of petroleum-based fuels with “drop-in” sustainable alternate jet fuels by 2018. So, understanding the potential air quality benefits of these alternate jet fuels from renewable sources is critical.”

According to Arunachalam, studies have shown that the more combustion becomes effective, the less emissions are discharged into the ambient air. Also, using cleaner fuel, either by switching the fuel out completely or reducing some amount of the adverse content in the fuel can reduce air pollution.

“A key impact there is sulfur content,” he says. “We have some sulfur levels in the aviation jet fuel. We found that just reducing sulfur content in the fuel on a global scale would lead to very large benefits of air quality and health.”

Arunachalam will present findings of this study to the FAA and other stakeholders at biannual meetings. The FAA and other stakeholders will use this research to develop policies to improve air quality.

Arunachalam says the impact of this study will be two-fold. The work will culminate in research papers for academic journals as well as provide the scientific-basis for creating policies that will benefit the environment and ultimately human health.

“We have made substantial progress over the last few years,” he says.

In addition to researchers and air quality modelers at the Institute, there are significant opportunities for students to get involved in this research.

“The ASCENT COE places a strong emphasis on training a new generation of scientists – so developing graduate students and post-doctoral scholars under this program has been a rewarding experience,” he added.

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