Nothing to sneeze at: Desert climate triggers allergic reactions for many residents

Monday, Aug. 23, 2004 | 11:05 a.m.

When Paul Franklin of Charlotte, N.C., moved to Las Vegas earlier this year, he suffered no allergies.

By mid-August he was in the examining room of a local allergist for treatment of congestion, coughing, sneezing and the sniffles.

"I came out to the desert and things got worse from the dryness, I guess," Franklin said. "I didn't have allergies until I came out here."

For those who have lived through many seasons in Southern Nevada, the term for Franklin's affliction is "Vegas throat," Dr. Jim Christensen of Las Vegas, said.

Christensen, a native of California who worked in Arizona before coming to Southern Nevada in 1990, said allergic reactions in a desert climate can be triggered by a change of temperature, humidity, dust or pollens.

This month and through October, Southern Nevada residents could notice sniffling, sneezing, scratchy eyes and throats as the fall season begins kicking up desert dust and producing pollens from grasses, trees and weeds.

The dry summer, augmented by the drought that has maintained its grip on the Southwest, has kept some allergens in check as few plants have produced enough pollen to affect those allergic to them, Christensen said. But the endless dry heat is not a help.

"There's really not a lot of pollen, but heat, dust and humidity have affected people's allergies," Christensen said.

Along with shifts in heat and humidity, rusts, molds and sooty particles affect people inside air-conditioned buildings and those working around outdoor standing water sources.

Normally human noses warm and humidify the air we breathe, Christensen said. Humidity ranging from 40 percent to 70 percent "is where our noses think we should be," he said.

Most days, humidity levels in Las Vegas are under 20 percent. When humidity increases, the weather changes intensify the allergic reactions.

While outside air may contain pollen, dust, cut grass or other irritants, inside modern buildings cigarette smoke, strong odors, perfume, chemicals, fabrics and flowers can trigger allergy symptoms, Christensen said.

When it comes to the outdoors, as Southern Nevada heads into its sixth year of drought there's little pollen in the air, University of Nevada, Las Vegas botanist Fred Landau said.

Most likely, desert pollens such as sagebrush and rabbit bush, growing at the 5,000-foot elevation or higher, could trigger some allergies in people enjoying the outdoors.

In the Las Vegas urban area, Landau said, animal dander and fine dust particles are probably to blame for in-house allergies.

"I've noticed people suffering," Landau said.

Though Southwestern desert communities were once considered barren lands devoid of airborne allergens, that's just not true anymore.

Many exotic plants introduced to the Las Vegas Valley have increased allergies among new and old residents, Landau said.

Enough pollen in the air to cause symptoms in moderately sensitive allergic patients is usually present at least nine months of the year in Las Vegas.

Yet pollen is not regulated under the Clean Air Act, said Christine Robinson, director of Clark County's Department of Air Quality and Environmental Management. The county does gather data on pollens at 21 monitors scattered around the valley.

Tree pollens from pines, mulberry trees and olive trees dominate the air from late January through early June. Grass pollen rises from March through October and weeds agitate allergy sufferers from April through October.

The first tree pollen appearing is usually of Mountain Cedar followed by Chinese elms, Arizona ash and cottonwoods. Mulberry pollen looms in March and April followed by European olive trees in late April through May. Oak is a latecomer from mid-May to early June.

Bermuda, rye and fescue grasses from lawns and golf courses produce from March through October.

The weeds include ragweed, rabbit bush and salt bush.

Although planting mulberry and European olive trees has been banned in Las Vegas since 1992, pollen levels continue to increase rapidly as existing trees grow bigger.

Olive pollen reached record highs in the spring of 1997 -- 38,933 grains per cubic yard of air -- at a new monitoring site at Bob Baskin Park on Oakey Boulevard.

Combined levels of olives and mulberry trees can soar to 60,000 grains per cubic yard of air anywhere in the valley and affect nearly anyone who is sensitive to those trees.

This year, as the drought continues, molds dominated the air quality monitoring sites both in the desert and near Griffith Elementary School on Essex Drive, northwest of Valley View Boulevard and Alta Drive.

The desert monitor recorded 1,371 grains per cubic yard of air on Aug. 15, compared with no trace of either olive or mulberry trees and no more than 7 grains of pine pollens in the valley's air.

For those with seasonal allergies, antihistamines, decongestants and steroid sprays may help relieve symptoms.

While a pill or capsule containing antihistamines or decongestants will work instantly, it takes four to six weeks for steroid sprays to begin relieving allergy miseries.

For a long-term solution to respiratory allergies, desensitizing shots may be used. The goal is to induce the body to tolerate small amounts of allergens, and the treatment can last six to eight months before benefits are apparent. Usually allergy shots are continued for two years, until symptoms decrease, before being discontinued.