Pollen season is right on time.

Byline: Tim Christie The Register-Guard

Research nurse Jean Jensen removed a small slide from a spore and pollen sampling machine mounted on the roof of a downtown Eugene medical office and placed it under a microscope on Tuesday.

There, on the slide, she saw a handful of tiny particles bearing the telltale pores and furrows of grass pollens.

The onslaught has begun.

Grass pollen season, the bane of allergy sufferers in the Willamette Valley, is here. The season usually peaks between Memorial Day and the Fourth of July.

"It looks like we'll be right on time with our pollen season," said Dr. Kraig Jacobson, an internist at Allergy and Asthma Associates in Eugene.

The pollen count taken by the clinic's research arm counted five grass pollens per cubic meter. The particles are about 25 microns, one-fourth the width of a human hair.

"It'll be higher tomorrow and get a little worse each day," Jacobson said. "If our weather stays like this, we will end up having high peaks before Memorial Day."

A high peak day is when pollen counts climb above 100 pollens per cubic meter.

"When it goes above 100 for the first time, that's when our phones light up like a lightning storm," Jacobson said. "That is the threshold where you've got masses of people going, `Whoa, this is terrible.' '

The pollen levels here are off the charts compared with other regions, he said. For instance, in most parts of the country, a pollen reading of 25 pollens per cubic meter is considered high, and a reading of 100 is very high.

"Around here, we routinely have counts over 400 to 500, and we have surpassed 1,000 per cubic meter," he said.

Grass pollen gets so thick in the Willamette Valley, that half the patients Jacobson sees don't even have allergies. But the pollens are so rampant, they penetrate biological membranes and cause allergic-like symptoms.

The agriculture and geology of Willamette Valley conspire to create a perfect setting for producing and trapping huge volumes of grass pollens.

About 80 percent of the world supply of rye grass seed is grown on 200,000 acres in Linn and Lane counties. Mountains on either side of the valley create "an enclosed air shed," Jacobson said. And the prevailing winds shift in spring, blowing from north to south, trapping the pollens in the valley.

As many as 35 million Americans suffer from seasonal allergies, according to the National Institute of Allergy and Infectious Diseases.

While everyone gets exposed to pollens, not everyone gets sick. Allergies develop when the immune system overreacts to a normally benign substance. When antibodies, designed to fight invaders, encounter allergens, they trigger the release of little packets of chemicals, including histamines and other compounds that cause common allergic symptoms: sneezing, coughing, postnasal drip, itchy eyes and throat and a runny or clogged nose.

Forecasting the severity of this grass pollen season is a little like predicting the weather, Jacobson said.

"In general, the milder and drier our winter, the more likely it is we'll have an earlier and heavier (allergy) season," he said.

Late rains can help temper the intensity of the season, he said.

COMBATTING ALLERGIES

Avoidance: Stay indoors as much as possible with doors and windows closed and air conditioner on. Don't drive with the windows down. Take a day trip to the coast or the mountains.

Medicate: You can get various antihistamines over the counter; Claritin and its generic equivalent, Alavert, are effective for many allergy sufferers. Prescription drugs include Allegra and Zyrtec. Steroid nasal sprays, sold by prescription only, also provide relief for many people.

Immunotherapy: People with symptoms severe enough to disrupt their work or social lives, or who develop asthma, may consider getting a series of allergy shots that get the body's immune system to tone down its attacks on allergens.