Commentary: How the use of drones can help us study atmospheric chemicals
There are a lot of chemicals in the air. Research has shown that they can be health-damaging and can affect the climate, but studies among these gases are still at an early stage. Matthew Stewart, a PhD student in environmental science and engineering at Harvard University, works in Harvard’s environmental chemistry lab to create sensors to put on drones. The sensors are used to examine the chemical concentrations of pollutants and emissions. NU Sci sat down with Stewart to discuss his findings.
How would you describe the purpose of your research?
The whole point of research is to just do things that no one has done which are useful to other people, and in terms of my skill set, I’m used to building things, with an undergraduate degree in mechanical engineering. I am not a chemist, so I am not going to pretend that I am one. But I do need to understand a bit of how these chemicals work in order to create these sensors because the way these sensors work is that they are sensitive to different gases. Maybe a surface which is particularly sensitive to carbon dioxide and it will absorb on the surface and it will change the property of the surface and from that you can work out what the concentration is if you calibrate it — the sensor — correctly.
So, is your main contribution to the research the building of the sensors, which could be useful for detecting atmospheric chemicals?
Yes. Essentially. A lot of other people in the group are chemists, they know what to look for, but they don’t know how to build something. So I am kind of the intermediate between theory and practice. I am not building the drone, but I am building the thing that goes on the drone so we can actually measure the stuff.
What would you say the implication of your research to the society at large is?
It’s hard to say until you’ve done the research because you don’t have any of the conclusions, but it would be interesting to see if there’s any correlation between these chemicals and mortality — so like death rates and illness rates — to see if there’s more of these particular chemicals then more people get sick and then we can try to work out if there’s relationship between these two things.
Would you say you are still at the early stage of this research?
Yes. Yes. Pretty much. There are a lot of chemicals in the atmosphere, there are thousands of them. Obviously no one has studied them all. And the concentrations are so small as well, we are talking about like in this whole room there would be maybe 10 parts per billion maximum. So when you think about out of a billion people in the world only 10 of them are that one thing, that’s not many at all. But they can produce a lot of other things, some of them are very bad, and some of them are fine for you, and how do we know which ones are good, which ones are bad. It gets very complicated very quickly.
During your research, did anything surprise you?
Since I am new to the field, a lot of things surprised me. I think just the fact that [you can] take something that was only developed a few years ago like drones, and then find actual useful things to do with it, which can contribute to human research and in life in general, that’s pretty cool. But also it means that we don’t know anything about how to use them. So it’s kind of trial and error right now.
What do you think the next step is?
Right now, it’s perfecting the technique of measuring, and try to build the new sensors. We’ve got a few proposals of new types of sensors that other people might use. I actually had a NASA proposal about developing a new sensor which will be used to measure low concentrations of gases in the atmosphere. We also want to add some other chemical sensors on that, things like ozone, as you probably heard of the ozone layer, so that’s an important thing to be measuring, especially because it affects the rate at which these chemicals are oxidized in the atmosphere. So that’s quite an important parameter. Things like that, CO2, methane.
Do you think a sensor can get as high as the ozone layer? Is that what you are trying to say?
Not really. The way it works is that you have the ozone layer, it’s between eight and 18 kilometers, depending on which part of the earth you’re on — so which latitude. And for us, ground-level ozone is much less than the ozone layer, but it’s still important because it has health implications. I remember being told that every 10 parts per billion increase in ozone, you decrease someone’s life expectancy by several months.
It’s crazy how our health is so closely connected to these chemicals.
It is. There have been a few studies on it, but unless you really think about it and study it, you wouldn’t really know. It’s kind of a silent killer.
Photos are courtesy of Matthew Stewart. The photos are from a recent field trip to Brazil.
