Up-and-down allergy season eases.

Byline: Joe Harwood The Register-Guard

This year's grass pollen season was like a roller coaster at a second-rate amusement park: most hay fever sufferers had ups and downs, but the ride wasn't all that intense.

"It was really an unusual season," said Jean Jensen, a research nurse with the Allergy & Asthma Research Group of Eugene, part of a private allergy clinic.

"Every time the grass (pollen count) would start to climb, we would get rain that would push it back down," Jensen said. "It certainly wasn't our worst grass pollen season."

The dreaded grass-pollen allergy season typically lasts about six weeks, between the bookend holidays of Memorial Day and the Fourth of July, and then abruptly ends - as it has this year.

Every time the southern Willamette Valley had a few days of hot weather with some wind during the peak season, allergy sufferers went into the red zone with the usual itchy eyes, runny noses and general misery.

But just as the pollen started sending immune systems into high gear and clogging mucous membranes, intermittent rains, sometimes true Oregon rain, would come along and knock the circulating pollen back down, Jensen said.

The beginning of the season was oppressive for allergy sufferers because a wet spring kept pollens from becoming airborne, she said, so when the weather turned warm and dry, there was plenty of pollen ready to circulate.

"It was tough on people because we went from a low count to a high count in a short amount of time," Jensen said.

Visits to her clinic correlated with the up-and-down pollen counts from mid-May through June.

But not all rain proved beneficial for allergy sufferers. Light, misting rain causes grass to release very fine, respirable pollen particles that wreak havoc on asthmatics, Jensen said. "We have some who say when it rains, they feel even worse," she said.

Any grass pollen count over 200 pollens per cubic meter is considered "very high" by the American Academy of Allergy Asthma and Immunology.

In the southern Willamette Valley - where about 80 percent of the world's rye grass seed is grown on 200,000 acres in Linn and Lane counties - it is routine during the pollen season for counts to register 400 to 500 pollens per cubic meter.

In the worst seasons, the count surpasses 1,000 pollens per cubic meter and is so thick that those usually unaffected by pollen start showing allergy-like symptoms.

The highest count this season was 541 pollens per cubic meter recorded by Jensen on June 9. Indicative of the quirky season, just one day earlier, the count had been a mere two pollens per cubic meter.

The same sneaky pollen buildup had occurred just before Memorial Day, Jensen said. On May 23, she recorded a count of 15 pollens per cubic meter. Three days later, it jumped to 375 pollens.

As the counts trend down - Friday registered at 6 pollens per cubic meter - it might be time to think about putting away the Benadryl, Zyrtec and Claritin. But just remember where you put those popular meds and other antihistamines, because there could be some residual days ahead when the pollen count jumps, such as a few consecutive days of hot weather with wind, to kick up the dust.