Report finds good air quality in Garfield County

County has been monitoring for pollutants since 2008

September 23, 2020

An air quality monitoring network has reported that Garfield County experienced good air quality index (AQI) for all 365 days in 2019. The consultant, Fort Collins-based Air Resource Specialists, presented the report, which summarized data collected by the county at monitoring stations located in Parachute, Battlement Mesa, Rifle, Carbondale and a location south of Silt, to the Board of County Commissioners.

The annual averages for volatile organic compounds (VOCs) and hazardous air pollutants (HAPs) continued to decline in the county, which has tested for these substances since 2008. The monitoring stations collect readings on 90 types of pollutants and toxins, in addition to criteria pollutant monitoring.

Criteria air pollutants, such as ozone, nitrogen dioxide and particulates (identified as particulate matter, or PM, 10 and 2.5), are subject to National Ambient Air Quality Standards (NAAQS) under the Clean Air Act and are monitored for in Garfield County. Each pollutant has a different standard for violations, and monitoring found that county ambient air quality did not violate PM2.5 standards for more than a 24-hour period in 2019.

PM 10 is about one-seventh the width of a human hair, while PM2.5 is roughly 30 times smaller than the width of a human hair. Both can be inhaled into the lungs while breathing. In 2019, the county saw 309 days of good air quality for ozone, which is measured by an eight-hour average, and 56 in the moderate category.

Emily Vanden Hoek, project scientist for Air Resource Specialists, told the board that data is collected from the monitoring sites and translated to the air quality index.

“You have a range that determines if air quality outside is good or maybe toward the moderate or unhealthy for sensitive groups category,” she said. “Most PM10 monitoring was discontinued
at the end of 2018, and there was one PM10 mobile monitoring station in Battlement Mesa in 2019. The standard is 150 micrograms per cubic meter over a 24-hour period. The highest
average at that station last year was 30, so PM10 is not an issue here in the county, though we still continue to monitor it at that location.”

PM2.5 are much smaller and can get deeper into the lungs, causing issues for the young, elderly and those with respiratory issues. The national standard is 35 micrograms per cubic meter over 24 hours, and the county has not surpassed the standard.

“In 2019, you have 365 days of good air quality and zero in moderate,” said Commissioner Mike Samson. “If you go back to 2018, you have one day of unhealthy air quality for sensitive groups and one day in the unhealthy category for eight-hour ozone.”

Increased wildfire activity, such as in 2018, can greatly impact the air quality in Garfield County, which saw 339 days with good air quality over a 24-hour period in that year. With two large fires in 2020 and smoke making its way into the area from fires in western states, air quality has been affected.

“This year, we’ve already seen several days in the moderate or unhealthy for sensitive groups category,” Vanden Hoek said.

The report noted that VOC levels were so low in Carbondale that monitoring was removed there after 2019. States use VOCs for health risk assessments, but there are no federal standards. Benzene and formaldehyde levels, which are associated with urban areas or oil and gas activity, have seen a significant decrease in Garfield County in recent years, according to the report.

“With propane and ethane, while not hazardous air pollutants, we’re seeing significantly statistical downward trends for those compounds across all monitoring sites,” Vanden Hoek said. “There have not been any violations of ambient air quality in Garfield County. Overall, most averages of VOCs continue to decline.”