Thursday, June 30, 2005
Copyright © Las Vegas Review-Journal

WILDFIRE EFFECTS: Blazes! It's a stew out there

Elevated levels of ozone and wood smoke particles spark health alert

The Stratosphere tower is silhouetted against the sunset Wednesday. Visibility estimates ranged from seven miles to 22 miles, down from the usual 70 miles in June. Photo by Craig L. Moran.

Smoke from wildfires in Southern Nevada, Arizona and as far as New Mexico drifted into Las Vegas on Wednesday, shrouding the city in an atmospheric stew of fine particles and ozone that triggered a health alert from air quality officials.

Clark County's Department of Air Quality and Environmental Management posted the alert on its air quality forecast Web site at 4:30 p.m. It said wildfires and a shift in low-level winds had caused elevated and unhealthful levels of ozone.

Mike Sword, the department's air quality engineering manager, said that besides ground-level ozone, which is a component of smog, the hazy skies contained levels of fine particulate matter from wood smoke that were four to six times greater than normal.

"My preliminary sense of it is that smoke is contributing to higher levels of ozone than we would typically see," he said.

Last year, Clark County was among urban areas in 31 states that were found to be in violation of the Environmental Protection Agency's eight-hour standard for ozone pollution. Though the county was in the least serious of the five designation tiers and has been developing plans to curb the problem, Wednesday's unhealthful levels could push it into a more serious category, Sword said.

Only one of the department's two visibility meters was operating Wednesday, he said. The other was down for annual maintenance.

Sword said haze from wood smoke at 2 p.m. had dropped visibility to 22 miles around Henderson and downtown Las Vegas, when it is usually as high as 70 miles in June.

But the National Weather Service reported that visibility in North Las Vegas was down to seven miles, and the monitoring station at McCarran International Airport recorded visibility at 10 miles for most of the day, dipping to seven miles for a brief period.

Brian Fuis, a National Weather Service spokesman, said light easterly winds pushed a smoke layer over Las Vegas Valley at 4,000 feet above ground. "Some of it trickled down. The lion's share is probably still aloft," he said Wednesday afternoon.

Most of the smoke plumes were from wildfires in Arizona and the Mesquite complex, but some flowed in from Farmington, N.M., where it was carried over the Grand Canyon and across Northern Arizona. One plume originated near Prescott, Ariz.

A shift in overnight wind direction was expected to blow some of the smoke out of the Las Vegas Valley.

"If things turn around a bit, it should be blowing back out of here," Fuis said.

Despite the smoke-related air pollution that filled the Las Vegas basin, a Clark County Health District official said surveys of emergency departments in the valley found no increases in recent days for respiratory complaints.

"Typically they do see small spikes when there are changes in air quality," said Dr. Lawrence Sands, a public health physician who is director of the district's community health division.

He acknowledged that smoke from wildfires can affect ground-level ozone, causing people with respiratory problems to have worse symptoms, such as coughing or shortness of breath.

"Others may have allergy symptoms, and others may have burning of the eyes or the throat," Sands said.

The fine particulate matter that makes up smoke acts as an irritant, he said. People with concerns about being outside in such conditions should check the air quality Web site and decide accordingly, he said.

"People basically have to go by what they are comfortable with. For most healthy people, it shouldn't be a problem," Sands said, adding, "People with respiratory problems might want to stay inside."

One Las Vegan who routinely spends time outside said that like many in the valley, his senses alerted him to the unusual conditions.

"I walked out this morning, and the first thing I noticed was the smell, the forest fire smell," said Von Winkel, a restoration ecologist for the Las Vegas Valley Water District at Springs Preserve.

"I certainly noticed the visibility. I couldn't see Sheep Mountains and could barely see Sunrise Mountain. Everything was obscured by the smoke."

Though the smoky conditions didn't affect him, he said, he had concern for his children, who have lung problems. "They could have complained about it, but they didn't," Winkel said.

Sands said that if wildfires persist during the summer and smoke continues to flow into the valley, greater precautions might be needed.

"It's going to vary from day to day. It's hard to predict. It's not just the smoke itself, it depends on what the weather conditions are," he said.

"I think the clue or prompt for people who have health conditions is to check the Web site."