air quality

Space experiment could teach us how aerosols move in the atmosphere

Teresa Donnellan — Mon, 05 Aug 2024 19:45:22 +0000

Space experiment could teach us how aerosols move in the atmosphere Teresa Donnellan Mon, 08/05/2024 - 15:45

As a child, Jeffrey Moran was fascinated by outer space. Now, he is designing an experiment to be carried out on the International Space Station (ISS) in 2025.

"I was obsessed with space as a kid,” said the mechanical engineering assistant professor. “The house I grew up in is still filled with drawings of Space Shuttles. Airplanes and spacecraft were a major reason I chose engineering when I got to college."

Jeffrey Moran. Photo by Office of University Branding

When the National Science Foundation issued a call for proposals to conduct research projects on the ISS to benefit life on earth, Moran jumped at the chance and wrote a proposal that was successfully funded. His grant-winning experiment will examine the extent to which aerosols (small particles suspended in air) move through air in response to a temperature difference (meaning the air on one side is hotter than on the other). This phenomenon—migration of particles in response to temperature gradients—is known as thermophoresis.

“It all started with a brainstorming session I had with a collaborator,” said Moran, describing the conversation he had with Purdue University colleague David Warsinger, who is a co-investigator on the NSF-funded project. “In contrast to most of my projects, which consider particles that move through liquids, we considered a simple question: what mechanisms could we use propel small particles through air?”

“My lab focuses on developing self-propelled particles for applications like water treatment or drug delivery," said Moran. "It’s a new and exciting field, but it’s so far been restricted entirely to water environments. No one has tried to develop a swimmer that moves in air. That ties into climate change, because aerosols are everywhere in the atmosphere—both because of human activity, like burning fossil fuels, and because of natural events like volcanic eruptions—and we don’t have a solid understanding of the net effect aerosols will have on the climate.”

Thermophoresis occurs in both liquids and gases, but it’s difficult to study in gases on earth because of the influence of gravity. Another challenge with studying particle migration in temperature gradients on earth is that the heated air tends to rise (for the same reason that hot air balloons rise), making it difficult to know exactly why the particles are moving. Doing the experiment in space allows scientists to run their tests with a minimal influence of gravity, to purely examine the effect of temperature on aerosols without creating air currents, which inevitably form when one tries to create a temperature difference in air because hot air tends to rise (which is the reason hot air balloons rise).

“We’re going to send various aerosol samples into space, each in a specially designed cuvette, for the astronauts to test,” Moran explained. “There’s a microscope on the ISS, and the astronauts will place our cuvettes into an apparatus we’ve designed that applies heat and cold to opposite walls of the cuvette. The astronauts will then use the microscope to determine how fast the particles move towards hot or towards cold. We expect that aerosols made from different materials will respond differently to the temperature gradient, but nobody knows how. That’s what’s exciting about this experiment – no one has made these types of measurements before.”

“For the last part of the project, we’re going to see whether some particles with asymmetric properties might generate the propulsive temperature difference on their own,” Moran continued. “These particles will have half of their surface coated in a metal. The other side is an insulating material,” Moran explained. “When we shine a light on them, the metal side efficiently absorbs the light and heats up relative to the insulating side. The hot hemisphere heats the air near it, and that creates a temperature difference in the surrounding air. This could help us understand whether odd-shaped aerosols in the atmosphere move on their own, without the need for a temperature difference.”

Before the experiment can be carried out, Moran and his team need to determine the experiment’s parameters as well as the materials required.

“This is very much a work in progress,” said Moran. “We're figuring out exactly which particles we want to send to the space station [based on] which materials matter the most to climate scientists [and] what the biggest question marks are.”

He mentioned, among other examples, the possibility of experimenting with carbon soot.

“Carbon soot is produced by burning fossil fuels, and it’s known to be harmful to the environment because it absorbs sunlight efficiently,” he said. “Another source of carbon soot, increasingly common in this era, is from rocket launches.”
“It’s pretty well established that carbon soot overall intensifies warming,” he said. “It's black, so it tends to absorb sunlight efficiently. This leads to a net warming effect on the atmosphere, but it's not clear how much it moves in thermophoresis (how much it moves in temperature differences).”

Moran looks forward to working with the National Aeronautics and Space Administration (NASA) to refine the plan. An early step in this project will be for Moran and his team to travel to Texas to examine a replica of the equipment available to scientists on the International Space Station.

The College of Engineering and Computing will cover Moran’s progress as the project moves forward.

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Jeffrey Moran

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College of Engineering and Computing

What to know about air quality alerts

Mary Cunningham — Thu, 08 Jun 2023 18:59:19 +0000

What to know about air quality alerts Mary Cunningham Thu, 06/08/2023 - 14:59

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Amira Roess, PhD, MPH

Air quality alerts are currently raised higher than usual along the eastern United States due to traveling smoke from Canadian wildfires. Epidemiologist and professor in Mason’s College of Public Health Amira Roess discusses what you need to know about air quality alerts and how it affects your health.

Why are wildfires in Canada affecting the air in northern Virginia?

The wildfires that are raging in Northeast Canada approximately 800 miles from those of us in the DMV (D.C.-Maryland-Virginia) are generating tremendous amounts of smoke and pollutants. Satellite imagery shows smoke blanketing our area and many other parts of the United States.

These fires are the worst that Canada has seen and are being fueled by a lingering high-pressure system over Canada for weeks now that has led to high temperatures and low precipitation. In addition to the high-pressure system, there is another low-pressure system in the northeast. Together these two systems are creating something like a pathway for smoke to move along over parts of the U.S.

How do I know what the air quality is?

There are many weather apps that now include air quality. The air quality scale most in use in the U.S. ranges from 0 to 300 and colors are assigned to the different ranges. The colors to look out for are:

Orange (101-150) is considered unhealthy for some populations and individuals who are vulnerable should avoid being outdoors.
Red is considered unhealthy (151-200) for all individuals, and everyone should limit their time outdoors, avoid strenuous activity, and wear a good quality N95 or K95 mask.
Purple (201-300) is considered very unhealthy for all groups and, in addition to the precautions taken under a red alert, everyone should stay indoors when purple alerts are issued.
Maroon (301) is considered hazardous, and we rarely see this.

Due to the smoke that is being generated by the Canadian wildfires currently, we are seeing red and purple alerts during much of the day. You can learn more about what these alerts mean from the U.S. Air Quality Index.

What can you do to protect yourself?

When air quality is suboptimal (orange), certain individuals should avoid being outdoors. Those with underlying conditions, especially respiratory and heart conditions, the elderly and young children should avoid being outdoors because they are at risk for the worst health impacts from poor air quality. When air quality is poor (red) or very poor (purple), which is what we are seeing right now, then all individuals should avoid being outdoors.

If you must be outdoors when air quality is poor or very poor, limit your time and you should wear an N95 or a KN95 mask. Remember that we want to make sure we use clean masks. These masks cannot be washed and once they are wet or dirty, they are a lot less effective, so discard them. Wearing scarves or bandanas is not at all effective at protecting you. It's very important to limit your time outdoors.

If you have pets that need to go out, take them out for short bathroom breaks only. Do not take them on long walks or have them do any strenuous activities. Remember that pets cannot wear masks as this can cause them to panic and can hinder their breathing. Late in the evening air quality tends to improve.

If you start to develop respiratory or other symptoms due to spending time outdoors, you should contact a health care provider immediately.

In addition to not going outside, what can you do to stay safe on a red or purple air quality day?

Limit how much outdoor air comes into your home.

Keep your doors and windows closed while air quality is poor or very poor.

When you are home, you can do small things to keep the indoor air quality good, such as not lighting candles and not using gas stoves, if you can avoid it.

Make sure your HVAC system is working efficiently. This means making sure that you change the filters as the manufacturer recommends and that you stick to your HVAC service schedule.

If you have neighbors or loved ones that are immune compromised or in the vulnerable groups mentioned above, check up on them and help them avoid being outdoors. You can do small things like taking their garbage out or walking their pets.

Are we going to see more of these situations?

In general, as we've seen a shift towards higher temperatures in our hemisphere, we are going to see more wildfires and other climate change-related disasters.

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Space experiment could teach us how aerosols move in the atmosphere

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What to know about air quality alerts

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