What They’re Thinking: Is the dust from gravel roads bad for you?

Patrick O'Shaughnessy worked in a construction job before beginning his public health research. Knowing firsthand some of the hazards facing workers, O'Shaughnessy dove into civil and environmental engineering work to help further employee protections throughout the country.

O'Shaughnessy, a professor in the Occupational and Environmental Health Department at the University of Iowa, has researched a multitude of topics but published research earlier this year studying how dust plumes from gravel roads — like those crisscrossing rural Iowa — travel in the air and affect the respiratory system.

This interview has been edited for brevity and clarity.

Q: What happens to someone’s lungs when they breathe in dusty air?

A: We do breathe in dusty particles all the time, but the main concern are particles that are small enough to get down to the bottom of the lungs. Our lungs are not just continuous receivers of particles, but rather they are capable of getting those little particles out of those dead-end spaces. It's kind of a push and pull between how much can they clear out those particles relative to how many are coming in.

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Q: From hazardous to benign, how hazardous is the dust from gravel roads? Should people be concerned about inhaling it?

A: When it comes to the dusty plumes from gravel roads, say after someone has driven on it, it is closer on the benign side. The gravel, which is essentially crushed limestone, is not on the list of organic substances that toxicologists would be really concerned about. But it is important to know that these are not pure substances; there are metallic substances that should not be ignored.

Q: What kind of metallic substances are there and what do they do?

A: Some roads have slag on them, or a steel manufacturing byproduct. The slag has been an exposure source for metals like manganese, possibly even chromium, nickel, which could add metallic stuff in your lungs, which may add to the toxicological effects. We found that there was a slight increase in manganese but it wasn't substantial, or to the point where we would think of it as a major concern. But there's also a potential ingestion hazard. The primary concern is among little children that are out in their front yard, when all of a sudden they're engulfed in this cloud, after a car goes by, creating a dusty plume and hitting their system like a shock wave.

Q: What did your study into gravel roads entail?

A: A Ph.D. student of mine and I put sensors on the side of gravel roads and over the past three or so years. We purposely picked high condition types of days so late July, early August. One of the problems with gravel roads is that it's not a very consistent output rate. With a gravel roads, there’s a massive puff every time a car goes by, and then it will settle down to almost nothing. We used an instrument that can measure these plume concentrations. Over seconds, and it'll show the sudden increase of dust, and then the decaying afterward as one car goes by. The Environmental Protection Agency measures it in averages throughout the year. So when we found that some days the plumes were over the EPA’s limit, it didn’t mean they were out of the regulations.

Olivia Cohen covers energy and environment for The Gazette and is a corps member with Report for America, a national service program that places journalists in local newsrooms to report on under-covered issues.

Comments: (319) 398-8370; olivia.cohen@thegazette.com