Smoke signals: Wood burning still pollutes Aspen

Mar 14, 2017

A dense fog hangs over Aspen on an early morning this winter.
Credit Elizabeth Stewart-Severy/Aspen Public Radio News

It’s an idyllic scene out of a ski resort ad: After a long day skiing, return home and warm your bones by the roaring fire. Donnie Lee, general manager at the Gant, knows the appeal this has for visitors.

“They come to the mountains,” Lee said. “The crackling of the wood and the smell of the smoke is certainly an ambience feature.”

That feature is unique to a handful of vintage complexes in Aspen, and there’s a reason that scene feels nostalgic.

To meet EPA requirements for clean air, the City of Aspen stopped allowing wood burning fireplaces in new construction about 35 years ago. Now Aspen’s air quality is typically quite good, but old timers remember when the town was blanketed in a brown cloud, in part because those old wood burning fireplaces are dirty.

Matt Coggon from the National Oceanic and Atmospheric Administration (NOAA) is studying Aspen’s wood smoke. Last winter, Coggon and other NOAA researchers measured the amount of fine particulates, called PM 2.5, in Aspen’s air. In resort towns, most of those tiny particles come from wood smoke, vehicles and restaurant grills. PM 2.5 is a concern.


“Those are the particles that can get deep into your lungs,” Coggon said. “They can penetrate very, very deep into your lungs and then contribute to pulmonary disease.”

To identify how much of that pollution comes from wood smoke, researchers use a tracer — a compound that only comes from burning wood. It’s called furan.

Jannette Whitcomb, Aspen’s air quality specialist, was instrumental in bringing the researchers from NOAA to Aspen. The data they collected, she said, “was so eye opening.”  

The amount of particulates in Aspen’s air spikes at certain times of the day. Those spikes “mimicked the marker for wood smoke,” Whitcomb said.  

Coggon and his team haven’t finished analyzing the data yet, but he says these spikes in Aspen are tied to time of day, when cars hit the roads and skiers come down and light fires.

“But the real driver of pollution events is always weather. It’s always meteorology,” Coggon said.

In Aspen, that meteorology deals with temperature inversions and a low ceiling. Inversions are common in valleys like this, which Coggon compares to a bowl. At night, as the snowy earth cools, the air close to the ground also cools down. At some point, a layer of air develops that is less dense than the air above it, and those layers, like oil and water, don’t mix.

“You have a lid on top of the air in your city and it doesn’t allow the pollution to get diluted or to exit,” Coggon explained. “And so it tends to cause pollution during the evening.”

In Aspen, that lid — or ceiling — sits only about 50 to 100 feet above town, which, Coggon noted, is not much higher than some of the tallest buildings.

Most of the pollution that hangs around the top of the buildings is from wood smoke, more than you might find in a bigger city. So even as the team at NOAA works to understand all the data they collected, Jannette Whitcomb wants the City of Aspen to make a change.

“That study started us thinking,” she said. “As the air quality specialist, I need to spend some time on wood smoke.”

It’s not clear yet what that looks like. The city doesn’t keep an inventory of how many wood burning fireplaces there are. The most recent count is 20 years old. The historic problem — when a brown cloud of pollution blanketed Aspen during temperature inversions — has been addressed. But Whitcomb wants to keep moving the dial by replacing the dirtiest source: wood fireplaces.

“It’s making a significant impact,” she said, even just replacing one fireplace at a time.

Large, multi-unit complexes might be a good place to make an impact by transitioning to gas fireplaces, but there are challenges.

Donnie Lee sits in front of one of the Gant's wood burning fireplaces.
Credit Elizabeth Stewart-Severy/Aspen Public Radio News

In a place like the Gant, with 143 units, cost is an issue. General manager Donnie Lee said it’s a conversation they’ve had, but to run gas to all the buildings and make the switch would be a $3 million investment.  

It’s also not clear yet what a total conversion to natural gas powered fireplaces would mean for greenhouse gas emissions. That work will mean partnering with the city’s climate action team, the Canary Initiative.   

Whitcomb will ignite the discussion about what that could look like this summer.