Allergy sufferers, especially in the Northeast, have been bemoaning record-setting or extremely high levels of tree pollen — the yellow dusty stuff coating cars, windowsills and just about everything else these days.

One-day measurements of 10,035 pollen grains per cubic meter of air in Waterbury, Conn., on May 4, and 6,813 particles per cubic meter in Philadelphia on April 30, are the highest levels measured at those locations in at least 15 years. The 6,790 reading in Armonk, N.Y., on May 3 is the highest since the station opened in 1995.

The Milwaukee-based National Allergy Bureau classifies measurements from 15 to 90 particles per cubic meter as "moderate," anything from 90 to 1,500 as "high," and anything above 1,500 as "very high."

"I've never seen anything over 5,000 before and anything over 4,000 is rare," says Aaron Rehl, the allergy bureau's program manager. "Anything over 2,000 or 3,000, you say, 'Wow.'"

‘Wow’

In recent weeks they've been saying "wow" around the Northeast and, to a lesser extent, the Great Lakes region. Eye-popping, eye-watering readings include measurements of 3,078 particles per square meter in Indianapolis on April 23; 2,163 in Washington, D.C., on April 25; 2,200 in Milwaukee on April 30 and 2,132 in Boston on May 4, according to the NAB's Web site.

"We had 2,200 around here last week," Rehl says. "You can see it around the office. You can hear it: The sneezing, the wheezing, the watery eyes."

Levels have fallen considerably since, but still can be classified as "high" or "very high" at many of the measuring stations. And some say weather conditions could cause further spikes.

"The reason I have people banging down the door of my office this year is the drought," says David Golden, an allergist in private practice and an associate professor of medicine at Johns Hopkins University in Baltimore, where he says tree pollen topped out around 1,500 parts per square meter.

"Whatever was there is still there; it's going to be there until there's some serious rain," he adds. "You get a breezy day, and all of a sudden you've got itchy, swollen eyes."

Allergy experts believe an unusual weather and temperature pattern is behind this year's high tree pollen levels. Normally, they say, different types of trees release their pollen at different times — with cedar and maple typically releasing their pollen early, followed by oak, pine and mulberry, according to one allergist.

This year, perhaps because of a wet winter followed by a belated and sudden warming, most trees seemed to release pollen at the same time.

"All these trees were there, I think, waiting to release that pollen," says Lida Pigott-Burney, director of the NAB pollen monitoring station at Fordham University in Armonk, N.Y.

Grass Pollen Season Coming

The good news? Tree pollen season may soon pass. The bad? Grass pollen is expected to follow right on its heels, perhaps arriving around Memorial Day. Opinions differ on how bad it might be.

"Certainly this is one of the worst [tree pollen] seasons in the last 15 years, if not the worst," says Dr. Christopher Randolph, director of the NAB's Waterbury, Conn., pollen monitoring station. "If tree counts are up, it's likely the grass and weed counts will be up. … I think we can say that we're in for a severe season."

While rain may be good for clearing away the tree pollen, another allergist says it may later cause problems with grass pollen.

"If we have no rain at all, we may not see a high level," says Dr. Donald Dvorin, director of Philadelphia's NAB monitoring station. "If it rains in the next several days, the grass will have a chance to grow more quickly and the pollen will be produced in the next seven to 10 days."