Pitkin County Skips Expensive Particle Counting for Airport Emissions

Pitkin County is choosing to ignore the science on ultra-fine particles for now.

That’s the short version of the decision the Board of County Commissioners made Tuesday. Instead of installing expensive, specialized equipment to count the invisible exhaust coming off the Aspen/Pitkin County Airport, the commissioners are betting on broader mitigation strategies. They’re going to cut emissions by 30% and let the chips fall where they may regarding the specific particle count.

It’s a pragmatic move, but it feels like a concession to the bottom line rather than a commitment to public health.

The controversy centers on ultra-fine particles (UFPs). These aren’t the dust you see floating in a sunbeam. They’re smaller than 100 nanometers. You can’t weigh them easily; you have to count them. And they come from jet engines, combustion engines, and wildfires. The science says they get into your lungs, your bloodstream, and potentially your brain. They cause respiratory, cardiovascular, and neurological issues.

But here’s the catch: no one has agreed on a limit.

The U.S. Environmental Protection Agency and the World Health Organization recommend monitoring in big cities. They don’t mandate it for regional airports like Aspen. There’s no universal protocol for how to measure these particles consistently over time. Is it worth spending hundreds of thousands of dollars to count something we don’t yet know how to regulate?

The cost drives the logic.

Dr. Roger Wayson, a noise and air quality engineer who presented to the board, laid out the price tag. Effective monitoring stations cost well over $100,000 each. Specialized equipment that tracks both size and quantity? Even more. And you can’t just plug them in anywhere. They need controlled environments, shelters, and line power. To get a real picture, you’d need multiple stations.

“We’re still finding out things almost on a daily basis,” Wayson said. “But there are some ongoing strategies.”

Those strategies involve mitigation, not measurement. The county’s resolution aims to reduce greenhouse gases and other pollutants by at least 30%. Jen Wolchansky, sustainability practice lead at Mead and Hunt, the airport’s environmental advisors, argues that cutting general emissions will naturally cut UFPs.

“It’s our responsibility to continue monitoring,” Wolchansky said, “to be able to have a safe, effective, efficient airport and to be able to take care of the community.”

She’s right. But the board is interpreting “continue monitoring” loosely. They’re prioritizing the reduction of sulfur dioxide — the stuff that makes your nose wrinkle when you’re driving down Highway 82 near the airport — over the precise counting of invisible particles.

Commissioner Patti Clapper pointed out a flaw in the current monitoring logic: the nighttime curfew. If planes are grounded at night, emissions drop. A snapshot reading taken at 2 a.m. doesn’t tell you much about the pollution generated during peak travel hours. The board is wary of spending big money on equipment that might just capture a skewed version of reality.

So, what are they actually doing?

They’re looking at synthetic aircraft fuels. They’re looking at operational changes. They’re betting that if you reduce the total volume of exhaust, you reduce the ultra-fines. It’s a gamble on the theory that mitigation is easier to manage than measurement.

For the folks living near the airport, the distinction might feel academic. You’re still breathing the air. You’re still paying for the airport’s operations. But the county is making a calculated choice: we know the particles are there, we know they’re bad, but we don’t have a standardized ruler to measure them precisely, and the rulers are expensive. So we’ll just try to make less of them.

“Mitigation is always important,” Wolchansky said. “This is a relatively new field.”

It is. And until the science settles on a limit, Pitkin County is deciding that reducing the source is a better use of taxpayer dollars than buying the best thermometer for the job. The outcome remains uncertain, but the county is betting that cutting the source beats counting the smoke.