Pollen allergies spring forward

Conditions a sign of global warming, researchers say

May 10, 2007|By Dennis O'Brien | Dennis O'Brien,Sun reporter

Fueled by a warm, dry spring, the 2007 allergy season has turned into one of the nastiest in recent memory, according to physicians and scientists who track pollen levels in Maryland.

"It's definitely the worst I've ever seen," said Dr. David Golden, an allergist who keeps a pollen counter on the roof of his Owings Mills office to track day-to-day conditions for allergy sufferers.

The first week of May is always considered a bad stretch for people with seasonal allergies. Trees that began producing pollen in mid-April continue to spread their misery, while grass pollen adds to the mix in May.

"If you happen to have grass and tree allergies, this is a really bad time," said Dr. Martha White, a Wheaton allergist.

And here's more bad news: Things could get worse as the climate heats up.

Researchers have found evidence that a warming climate will enhance the growth of the pollen-producing trees and weeds that make people sick.

In a series of studies over the past decade, Lewis Ziska, a weed expert with the U.S. Agricultural Research Service in Beltsville, has found that oak trees and other pollen producers grow faster in urban settings where warmer temperatures, longer growing seasons and higher carbon dioxide levels mimic the conditions that experts predict will be widespread in coming decades.

Ziska found that oak trees and ragweed, both pollen producers, thrive in urban heat islands that are about 5 degrees Fahrenheit warmer than suburban and rural areas.

His findings, based on growth of trees and plants observed in Baltimore and Frederick County, are included in the International Panel on Climate Change report released last month.

The report, one of three released by the IPCC this year, examines the effects of climate change on health and the environment.

"Some of the plants we don't like may be the ones that do the best in a warmer world," said Jonathan Patz, a University of Wisconsin professor of environmental studies and an author of the IPCC report.

Too many variables are at work to definitively link climate change with an increase in the numbers of people getting sick, Ziska said. But he and other researchers say studies of recent growth patterns are intriguing.

"It's hard to say what the world is going to be like in 50 years - things change," Ziska said. "But what we see, in fact, could be a harbinger of things to come."

Seasonal allergies can strike at any age. About 19 million adults and 8 million children suffer from them, according to the federal Centers for Disease Control and Prevention.

Weather factor

Tree pollen peaks in late April and usually starts to drop by early May, while grass pollen peaks from late May to early June, said Susan Kosisky, who operates a pollen counter for the Army at the Walter Reed Army Medical Center annex in Silver Spring.

But this year, a spell of warm, dry weather led to some record-high tree pollen counts in April and kept the counts unusually high this month, until this week when levels started to drop, Golden said.

Pollen levels are measured by trapping and counting the number of grains per cubic meter of air.

At the Owings Mills station, Golden and his partner, Dr. Jonathan Matz, recorded 1,785 grains per cubic meter for the 24 hours that ended April 23 - the highest pollen level in his 11 years of counting, Golden said.

Allergists consider anything over 1,000 grains extremely high.

A pollen counter on the roof of the Walter Reed Army Medical Center annex in Silver Spring recorded 2,255 pollen grains April 23, said Kosisky, who is assistant chief of the allergen extract lab at Walter Reed. That's not an annex record, but it culminated four days of near record counts and prompted many patients to wonder what was causing their symptoms, she said.

"I've had patients calling, and I've got friends and family with allergies and they've been asking about the pollen this year," Kosisky said.

Counts from the Owings Mills and Silver Spring stations are reported to the American Academy of Allergy, Asthma and Immunology, and posted on the Web site of the organization's National Allergy Bureau. The Golden and Matz counts also are broadcast on area radio and television stations and published in The Sun.

Trees `exploded'

Kosisky blamed the pollen levels on the warm, dry spring. "There were warm days, when it was in the 80s in April, and the trees just exploded with pollen," she said.

As a result, doctors say, they've been treating more allergy patients this year, often with more serious symptoms than in years past.

"I'm seeing people come in with more asthma, more eye symptoms and more rashes," said White, an allergist for 25 years. "This year ranks up there in the top 10 percent."

Skin rashes are a common symptom among children with seasonal allergies, she said. Many people have both asthma and seasonal allergies.

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