Nav: Home

Aviation emissions' impacts on air quality larger than on climate, study finds

November 07, 2019

New research from the Massachusetts Institute of Technology (MIT) has quantified the climate and air quality impacts of aviation, broken down by emission type, altitude and location.

The MIT team found that growth in aviation causes twice as much damage to air quality as to the climate.

Writing today in IOP Publishing's Environmental Research Letters, they examine how this damage can be mitigated, and provide consistent comparative assessments of aviation emissions trade-offs, considering both climate and air quality impacts.

The lead researcher on the study, Dr Sebastian Eastham, from the Laboratory for Aviation and the Environment in MIT's Department of Aeronautics and Astronautics, said: "Aviation emissions are an increasingly significant contributor to anthropogenic climate change. They cause five per cent of global climate forcing.

"When you consider the full flight, which includes emissions from takeoff, cruise and landing, aircraft emissions are also responsible for around 16,000 premature deaths a year from impaired air quality. This is small compared to other sectors, being only around 0.4% of the total deaths attributed annually to global air quality degradation, but is often overlooked in policy analysis."

"The challenges for aviation sector decision makers wanting to reduce these impacts are the trade-offs between different emission types, and their impacts in different locations."

Historically, attempts to address the climate and air quality impacts from aviation have been through changes in policy, technology, and/or operations - improvements to fuel efficiency; more stringent emissions standards; market-based measures to reduce CO2 emissions; or the introduction of sustainable aviation fuels.

But the study notes reducing one type of emission can come at the cost of increasing another, either in absolute terms or by limiting potential reductions offered by new technology.

Dr Eastham explained: "We could decrease NOx emissions by designing engines with lower combustor temperatures. However, the resulting loss in thermodynamic efficiency would mean we need to burn more fuel, meaning more CO2. These are the types of trade-offs that need to be quantified, and our study offers a fast way for decision makers to do this.

"We developed a set of metrics for comparing the climate and air quality impacts of aviation emissions at all flights stages, by estimating the social costs per unit of emitted pollutant. The cost metrics are broken down by flight phase - cruise, landing and take-off - and by the geographical region of emission, both per kg of emission and per kg of fuel burn."

The research team applied the metrics to evaluate the effects of a global expansion in aviation, consistent in magnitude with its current annual growth. They then used this as a benchmark for three scenarios.

First, they considered a growth scenario with fuel efficiency increases and reductions in NOx emissions factors consistent with 10-year goals. Second, they evaluated the trade-offs between the climate and air quality impacts of engine-based NOx emissions reductions. Finally, they re-assessed the climate and air quality trade-offs of jet fuel desulphurisation.

Dr Eastham said: "Our results show three components are responsible for 97 per cent of climate and air quality damages per unit aviation fuel burn: air quality impacts of NOx at 58 per cent; climate impacts of CO2 at 25 per cent; and climate impacts of contrails at 14 per cent. It is important to note that the vast majority, around 86 per cent in fact, of the NOx impacts on air quality are due to the emissions from cruise as opposed to the landing and takeoff cycle. These components - cruise NOx emissions, CO2 emissions, and contrails - are therefore primary targets for future strategies to reduce the atmospheric impacts of aviation emissions.

"To reduce the climate impacts of aviation, measures aimed at reducing CO2 emissions and contrails are likely to have the greatest net climate benefit. In contrast, we found that 94 per cent of air quality impacts are driven by NOx. This suggests that measures aimed at reducing NOx emissions during cruise could lead to the greatest net benefits, even if they cause a small but uncertain climate NOx disbenefit and a small decrease in fuel efficiency.

"Finally, we found the air quality impacts of aviation emissions significantly exceed the climate impacts, with air quality impacts being 1.7 to 4.4 times higher than the climate impact per unit of fuel burn. This must be contrasted to ground-based industries, where post-combustion emissions control and access to cleaner fuels is widespread. For example, the climate impacts of the US power sector are of similar magnitude as the air quality impacts following significant declines in co-pollutant emissions over the past 15 years. This points towards potential political and technological opportunities for reducing the atmospheric impacts of the aviation sector."
-end-


IOP Publishing

Related Air Quality Articles:

Can poor air quality make you gain weight?
A new study links air pollution to changes in the human gut microbiome which could fuel diabetes, obesity and inflammatory bowel diseases like colitis and Crohn's disease.
TRAX air quality study expands
In a new study published in Urban Science, researchers including Daniel Mendoza and Logan Mitchell report the latest from the TRAX Observation Project, including data validation studies that bolster the data's value for other researchers and three case studies from recent events showcasing the abilities of the mobile air quality sensors.
Automobile law in Japan has improved air quality
A law passed in Japan in 1992 aimed to improve urban air quality by banning vehicles that violated certain emission standards from being registered in designated areas.
Air quality tests need simplifying to help reduce dangerous emissions
New methods of testing and simulating air quality should be considered in order to help policy makers have a more accurate understanding of how emissions affect air pollution levels, new research suggests.
How are Utah's dry lakes impacting air quality and human health?
A new study from BYU reveals that 90 percent of Utah urban dust comes from dry lakebeds, which not only impacts air quality but also impacting soil and what can grow in it.
A large part of the school buildings in Andalusia does not have adequate air quality
A high percentage of schools buildings in Andalusia does not have the necessary mechanical ventilation equipment or filtration systems in place, so air has to be renewed by means of infiltrations or opening the windows.
Study: Actually, potted plants don't improve indoor air quality
Plants can help spruce up a home or office space, but claims about their ability to improve the air quality are vastly overstated, according to research out of Drexel University.
House developers could be the secret weapon to improving air quality
House developers and urban planners could be the unlikely heroes in the battle against the 'new tobacco' -- air pollution -- say researchers from the University of Surrey.
Treat citizens as partners, not participants, to improve air quality research
Encouraging citizens to take part in almost every step of scientific air quality research improves their understanding of how air pollution affects their health, finds a new study from the University of Surrey.
Monitoring air quality after Fourth of July fireworks
The U.S. recently celebrated the Fourth of July with dazzling fireworks displays in many cities.
More Air Quality News and Air Quality Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Teaching For Better Humans 2.0
More than test scores or good grades–what do kids need for the future? This hour, TED speakers explore how to help children grow into better humans, both during and after this time of crisis. Guests include educators Richard Culatta and Liz Kleinrock, psychologist Thomas Curran, and writer Jacqueline Woodson.
Now Playing: Science for the People

#556 The Power of Friendship
It's 2020 and times are tough. Maybe some of us are learning about social distancing the hard way. Maybe we just are all a little anxious. No matter what, we could probably use a friend. But what is a friend, exactly? And why do we need them so much? This week host Bethany Brookshire speaks with Lydia Denworth, author of the new book "Friendship: The Evolution, Biology, and Extraordinary Power of Life's Fundamental Bond". This episode is hosted by Bethany Brookshire, science writer from Science News.
Now Playing: Radiolab

Space
One of the most consistent questions we get at the show is from parents who want to know which episodes are kid-friendly and which aren't. So today, we're releasing a separate feed, Radiolab for Kids. To kick it off, we're rerunning an all-time favorite episode: Space. In the 60's, space exploration was an American obsession. This hour, we chart the path from romance to increasing cynicism. We begin with Ann Druyan, widow of Carl Sagan, with a story about the Voyager expedition, true love, and a golden record that travels through space. And astrophysicist Neil de Grasse Tyson explains the Coepernican Principle, and just how insignificant we are. Support Radiolab today at Radiolab.org/donate.