When Linsey Marr’s son was in day care, she said, “It seemed like we were getting a call every other week to come pick him up because he was sick.”

Marr, a professor of civil and environmental engineering, was puzzled. On her trips to the daycare, she had seen the staff constantly wiping down surfaces, washing hands, and sterilizing any toys that ended up in a child’s mouth (no small feat in a room full of toddlers).

So why, with those scrupulously clean surfaces, were these kids still getting sick all the time?

Could it be the air?

She looked through the literature on the airborne transmission of common diseases like the flu. But she was surprised to find that there wasn’t any consensus on how much of the flu was spread through the air, or what environmental factors affected it.

So she took the question back to her lab, which already studied the way invisibly tiny particles in the air affect our health.

To learn what she found, and what she’s doing now, check out this article coming out Tuesday in VT News.

The daycare contagion conundrum wasn’t the first time Marr — who was recently featured in Popular Science — had noticed something in her world that others might have taken for granted, and turned it into a research question.

She’s an avid runner, and when she was in graduate school, she said, “I used to run by this big train depot, and I’d just be breathing that stuff — diesel exhaust — and I’m just thinking, ‘wow, am I killing myself? Is this actually a benefit for me to go running?’”

It was those questions that originally led her to study particulates in the air.

So these days, Marr is very aware — much more than the rest of us — of what’s getting sucked unnoticed into our lungs.

Has that made her nervous about, well, breathing? It’s “a little anxiety-inducing,” she admitted, but she’s been doing it for so long, she says, and she’s gotten used to it.

By Eleanor Nelsen, communications manager of the Institute for Critical Technology and Applied Science.