Wildfires taking toll on valley air quality

Ed Koch and Launce Rake

Tuesday, July 16, 2002 | 11:09 a.m.

Unhealthful air quality readings were recorded in Clark County for a second straight day, with dangerously high levels registered Monday. Wind-whipped smoke from wildfires hovered as a thick gray haze over the Las Vegas Valley.

On Sunday the sixth unhealthful air quality day this year -- double last year's total -- was recorded at just the Mesquite monitoring station. Monday was a different and more alarming story.

"Between 9 a.m. and noon, almost every one of the 26 monitoring stations had high readings for (pollution) particulates," said Femi Durosinmi, air quality monitoring supervisor for Air Quality Management. But, this morning, he said, "things are looking pretty good. We got some good wind last night."

Donald Maker, a meteorologist for the National Weather Service in Las Vegas, said the 15-20 mph winds from the southeast that brought in smoke from area wildfires shifted, bringing in cooler northwest breezes that blew out much of the unhealthy air.

Maker said pollution levels could be further reduced today if the the region gets rain. He said there is a 30 percent chance of thunderstorms later today.

A dangerous air quality advisory was issued early Monday afternoon by the agency, but was lifted by late afternoon.

Carrie MacDougall, assistant Air Quality Management director, said the bad air resulted from an unusual combination of meteorology and smoke from forest fires in Arizona and the nearby Spring Mountains.

Ordinarily the smoky gases from the fires would have dispersed. But because of a thermal inversion parked over the Las Vegas Valley, gas molecules clumped together to form fine particles, she said, noting, "We don't usually get this type of meteorology in the summer."

MacDougall said the air was not only bad for sensitive groups such as older people, children and those with pre-existing breathing problems, but also for "those who are even in good health."

Readings of particulate matter -- or fine dust -- throughout the valley reached peaks above the federally defined "very unhealthful" levels of 201 micrograms per cubic meter of air.

High readings included 284 micrograms downtown, 279 at Gowan Road and Buffalo Avenue in Lone Mountain and 302 micrograms in Green Valley. All but a handful of the stations recorded levels above 201.

However, as conditions improved throughout the day and into the night, the daily averages wound up under 100 -- or moderate, which is still unhealthful, Durosinmi said. Green Valley had the highest daily average of 95.

There were seven unhealthful days this year compared with three for last year and 19 for 2000, Durosinmi said. In addition to the two this week, there was one unhealthy day each in January, February and March and two in April.

The bad air days were not expected to affect the Environmental Protection Agency's review of local clean air plans for controlling particulate matter, because a plan to fight air pollution has been put in place.