Ozone levels, ‘brown cloud’ cause concern

GLENWOOD SPRINGS — Preliminary monitoring results this summer showed Garfield County ozone levels once exceeded and twice flirted with the federal action level.

However, that standard is based on a three-year average, and the county has completed only its first year of ozone testing.

“It’s just very premature to take this and compare it to the standard at this time,” Paul Reaser, the county’s senior environmental health specialist, told county commissioners Monday.

County health officials believe wildfires outside the county were partly responsible for the highest readings this summer. Jim Rada, the county’s environmental health manager, said when a county reading exceeded the federal standard

July 9, the same thing was occurring across western Colorado.

On that day, the county’s Rifle monitoring station recorded an eight-hour ozone reading of 81 parts per billion.

The federal standard is 75 ppb. But that’s based on a three-year average of an area’s fourth-highest daily maximum eight-hour average. In Garfield County, that average this summer was 74 ppb, based on July 11 and 24 readings.

As has been seen in Denver, violating ozone standards can result in actions such as crackdowns on emissions from vehicles, oil and gas operations and manufacturing.

One reason for Garfield County’s interest in ozone levels is the high levels recorded last winter in rural Pinedale, Wyo., which like Garfield County is a center of oil and gas development.

Ozone more typically is a summertime problem that occurs in urban areas.

Rada said even a short-term high ozone reading can be a health concern, particularly for sensitive populations such as the old, young, and people with certain health problems. Such people could benefit from real-time air quality data that might help in deciding whether to engage in high-exertion activity, he said.

The county is going to make access to such data available via its Web site, http://www.garfield-county.com. The county is monitoring particulate matter, volatile organic compounds and other
pollutants, as well as visibility.

Reaser noted concerns that have begun to arise about the appearance of a “brown cloud” over Parachute. Particulate matter might be one cause of it, he said.

He said measurements show a possible upward trend in PM10, or coarse particulate matter, over the decade in Parachute.

This year’s readings showed a continuing increase, but the readings were influenced by a construction project near the monitoring station.

One reading well above the federal standard resulted from grinding work at the construction site.

The county began testing this year for PM2.5, a finer particulate.

Preliminary annual average measurements were well below the federal standard that is based on three-year averages.

A 24-hour average also used as a federal standard wasn’t exceeded, although hourly measurements occasionally spiked above that benchmark.


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