Published: March 18, 2021 By

Shelly Miller headshotShelly Miller solves problems she cares about. As a CU Boulder mechanical engineering professor, her expertise on aerosols, indoor air pollution and urban air quality catapulted her to a global spotlight in 2020, giving her the chance to make huge world changes, fast. She discusses her work, the pandemic and what it’s like being suddenly in high demand. 

When you first became an engineer, what were the problems you cared about and are now trying to solve? 

Growing up in California, we were sent home from school for bad air quality days. In environmental engineering classes, it really clicked for me that my interest in air pollution was related to growing up in California. I think of the environment as a shared resource. I want to preserve and improve the quality of the air, water and environment for everybody. 


What are aerosols and how do they impact health? 

Aerosols are simply particles suspended in a gas. The particles can be made of anything and can be solid or liquid. They are a main cause of adverse health effects and a major contribution to air pollution.

When did you realize the link between your work and COVID-19 research demands? 

I worked on engineering controls for tuberculosis transmission for my PhD dissertation. After COVID showed up in the U.S., my colleagues and I started emailing each other saying, ‘This looks airborne. We have to tell people how to keep themselves safe indoors.’ Outbreaks led us to quickly realize that most transmission was happening indoors.

What are the biggest challenges facing schools? 

Schools need to understand the two main routes of aerosol transmission and how to mitigate those routes. The first is short-range exposure. This happens within personal spaces — a teacher standing over a student or kids working on a project together. The only way to mitigate that kind of interaction is by wearing well-fitting masks at all times. The second (long-range transmission) requires cleaning the air and making sure good ventilation systems are in place.

What should people be doing at home? 

Make sure you can open your windows — even small openings will help. If your exhaust hood vents outside, turn it on with a window open. Also, run your furnace, because the air will circulate through a pretty coarse filter. If you don't have an air cleaner, stay socially distant and wear masks if sharing the air with others that might be infectious. 

In 2020, you did COVID-centered research related to the performing arts. What do you think the future looks like for musicians? Music students, indoors, social distanced wearing masks

We have been really successful mitigating risk in music classes and marching bands. We haven’t had a single reported transmission to date in music programs following our guidance. Mitigation measures are quite limiting, but I wouldn’t recommend playing music without them. I think professional musicians are going to need to be tested daily or weekly to be able to do their work

How many schools have you been working with locally or nationally?

When we first shared our research, people were calling from places like Germany, France and Florida. There are probably hundreds of schools we don't know about. In fact, my friend, whose daughter plays oboe at a college in Minnesota, said, ‘Oh, my daughter is using your mitigation strategies.’ I didn't even know, so that was pretty cool.

Since the pandemic started, you’ve been busier than ever. Your email signature alludes to the fact that you are juggling hundreds of emails a day, work, family, sleep and wellness. How have people responded to your endeavor for balance? 

At first, so many of my colleagues — especially my female colleagues — got back to me and said, ‘I love your signature. I'm going to do that,’ and they did. I thought that was a really important statement to make.

Some might call you an aerosol superstar. 

I don’t know if I feel like a complete superstar, but I do feel that I have a way of communicating science that speaks to a lot of people. There’s an audience that really learns from what I have to say. That feels important to me.

What new directions are you taking with your research? 

I would be interested in doing research showing the best way to cleanse the air. There are a lot of ionizers being sold, and there’s no scientific support for their efficacy. In fact, some data show that they can cause worse problems. So, it’s important to try and help people understand which types of air cleaner are effective versus which ones are just a marketing hoax. 

What changes do you anticipate happening in indoor environments post-COVID? 

I hope people understand that their environments affect their health, and your home is not guaranteed to be a healthy place — you need to work to make it healthy. Instead of just making buildings thermally comfortable, we need to provide enough outside air ventilation and good filtration in energy-efficient ways to maintain health. 

Shelly Miller with student wearing face masksWhat do you hope we learned from this pandemic about how indoor spaces impact health? 

I hope we learn to trust science again and know that there is a scientific process we go through that evolves and new answers come from it. I feel like we’ve moved away from that.