OnAir@AAAR: Urban V. Rural—How Do Coarse Particles Compare?

I sat down with Mike Hannigan, EPA grantee and UC Boulder scientist, Tuesday to talk about his innovative research on coarse particles.

mike hannigan

“Coarse particles are basically what we think of as dust,” Hannigan explained.

“But what’s tricky is that depending on where you are, the dust can look very, very different.”

In an urban environment, for example, a large percentage of coarse particle pollution comes from the brake-wear of stopping and slowing vehicles. In rural areas though, agricultural dust and windblown soil play a big role.

“The major question we’re trying to answer is—do these different kinds of coarse particles cause different health effects? And if so, should this impact the way coarse particles are managed in the future?”

A handful of studies have suggested increased hospitalizations for cardiovascular and respiratory illness with exposure to coarse particles, but a comparison of urban and rural effects has never been done before.

Hannigan and colleagues set up monitors in Denver, Colorado and in a rural town called Greeley, about 100 miles to northeast of Denver. The monitors measure both coarse and fine particles continuously, producing hourly averages that give a clear picture of how particle exposures vary over time.

Hannigan’s group has been monitoring for just over a year and will continue for another two. After monitoring is complete, the data will be turned over to epidemiologists to look for any associations between coarse particles and hospitalizations, deaths, and birth outcomes in Denver and Greeley.

“ Nobody has ever looked at birth outcomes as a possible effect of coarse particle exposure before,” Hannigan said, “so this is very new.”

Over the three years of monitoring, Hannigan and colleagues will also collect samples for lab analysis in an effort to determine the origins of coarse particles in each area.

“You can measure barium in samples, for example,” Hannigan explained, “and since brakes are really the only place you find barium… that tells us something about the source of those particles.”
In the future, Hannigan hopes to expand his analysis to include biological sources of coarse particles like pollen and bacteria.

“We can sequence the DNA of particles off the filters from the field and understand more about where they are coming from,” he said.

“It’s all very exciting; it’s going to add a lot of knowledge to the scientific community.”

About the Author: Becky Fried is a science writer with EPA’s National Center for Environmental Research. Her OnAir posts are a regular “Science Wednesday” feature.