Pitkin County decides to hold off monitoring for ultra-fine particles

Mead and Hunt, the environmental advisors to the Aspen/Pitkin County Airport, presented to the Pitkin County Board of County Commissioners on Tuesday about monitoring and mitigation strategies for air pollutants, specifically ultra-fine particles.

Ultra-fine particles are particles smaller than 100 nano-meters in diameter, meaning they are not measured in mass but instead in particle count. They are generated by combustion engines, jet engines and wildfires, and have been shown to lead to respiratory, cardiovascular and neurological health effects, according to Jen Wolchansky, Mead and Hunt’s sustainability practice lead. 

Because the health effects change drastically depending on exposure time, the quantity of particles and those particles’ relative toxicity, there is no limiting factor on how dangerous it is in proximity to ultra-fine particle emission.

“It’s our responsibility to continue monitoring [ultra-fine particles], understand the evolving science, technologies, policies and issues that we are at the forefront of … to be able to have a safe, effective, efficient airport and to be able to take care of the community,” Wolchansky said.

Yet despite potential health impacts, no limits have been set domestically or abroad. Instead, many organizations such as the U.S. Environmental Protection Agency and the World Health Organization recommend monitoring in large urban areas. 

There are also no universal protocols for how to measure ultra-fine particles, which makes it difficult to measure consistently over a long period of time.

According to Dr. Roger Wayson, a noise and air quality engineer who presented to the BOCC, most of the effective monitoring stations cost well over $100,000, especially the more specialized equipment that monitors size and quantity of particles. Many also require a controlled environment, shelter and line power, and multiple stations would be required to effectively monitor for ultra-fine particles.

According to Commissioner Patti Clapper, the airport’s nighttime curfew may also skew emission readings and not give an accurate representation of the airport’s pollution.

Because of how relatively little is known about the health effects of UFPs and how expensive and rapidly evolving the monitoring equipment is, the BOCC is electing to move forward with mitigation strategies the airport is already considering. The BOCC resolution and common ground goal for the airport aims to “reduce greenhouse gases and other pollutant emissions by at least 30%” at the airport. 

According to Wolchansky, these mitigation efforts will reduce all emissions, including ultra-fine particles and sulfur dioxide, which can sometimes be smelled from the areas surrounding the airport.

“Mitigation is always important and, again, this is a relatively new field. We’re still finding out things almost on a daily basis, but there are some ongoing strategies,” Wayson said.

The airport could increase use of synthetic aircraft fuels that use a lower sulfur content, or use hydrogen fuels which burn cleaner, according to Wayson. The airport could also consider replacing diesel powered vehicles and equipment with electric ones that emit almost nothing. Gate electrification would also allow docked aircraft to stay plugged into power without running their engines at a low power level, lowering emissions. 

Wayson noted that these are important solutions because the airport has more control over these on-site practices than what fuel jets are landing with and how clean those jets are.

Clapper said she sees opportunity for further research on airport air pollution at the Aspen/Pitkin County Airport that could help airports around the world. Wayson noted that very few airports actually monitor ultra-fine particles in the U.S. now, and that those airports often only have limited monitoring equipment that isn’t able to consistently attribute emission sources, and sometimes can only count particles but not identify their size or type.

“This might be a great opportunity to look at some kind of research for institutions or organizations who might be interested in doing something that’s rethinking high altitude or proximity to rural communities,” Clapper said.