The area's long, lush spring has produced an abundance of tree pollen to bedevil allergy sufferers. But weeping, sniffling victims might take comfort in the fact that this year's pollen levels haven't come close to past records.
"I know people don't want to hear this, but the season's only been average or slightly worse than average," said Towson allergist John Bacon. "There's a nice crop out there, though. It's been good growing weather."
Tree pollens are Mother Nature's opening salvos in the annual seven- to eight-month hay fever onslaught that begins as early as late February and ends with the first heavy frost, sometimes well into October.
Most trees are wind-pollinated, which means the powdery yellow grains from male flowers are dispersed through the air to the tree's female flowers for fertilization.
And there's a nasty, sniffly progression of pollens throughout the spring as various tree species bloom, from maples and willows and mulberries to oaks, the most prodigious supplier of pollen in the Baltimore area. Levels of tree pollen have already peaked, said Dr. Robert Hamilton, director of the Dermatology, Allergy and Clinical Immunology laboratory at the Johns Hopkins University Asthma and Allergy Center, where the daily pollen counts are made. On April 16, the combined tree pollen was measured at 5,061 grains per cubic meter, with another high reading of 3,696 on April 17. After a spell of rainy weather, the tree pollen rebounded to 3,692 on April 30 and 2,589 on May 1. By May 14, the count had dropped to 421. If those counts appear suspiciously small, it's because Frank Ward -- Baltimore's "Mr. Pollen," who retired last year after 30 years -- reported oak pollen readings as high as 35,000.
But his time-honored method of exposing a sticky, spinning slide to the open air for 24 hours and then counting the pollen grains on the slide did not take into account the volume of sampled air.
Enter Dr. Hamilton's more accurate sampling instrument, which makes calibrated measurements of pollen in grains per cubic meter to conform to national standards.
"Obviously, we didn't experience record [tree pollen] levels this year," Dr. Hamilton said. "But the grass pollens are just coming on, and they tend to peak from mid-May to mid-June."
The sneeze parade then continues with common weeds such as English plantain, and the most despised of all -- ragweed -- arrives in late summer, reaching its annual peak around Labor Day.
An estimated 15 percent of the population has allergic reactions to pollen, ranging from mild sneezing to near incapacitation from swollen nasal membranes and red, watering, itchy eyes.
Allergist Philip Norman, professor of medicine at Johns Hopkins, reports "an unusual number of calls since March" from hay fever patients. For borderline sufferers, only high concentrations of pollen may sensitize them enough to initiate symptoms. But many veterans of the allergy wars react to even small levels and have hay fever in all but the dead of winter.
Treatment for the symptoms ranges from various nasal sprays ** and medicines such as terfenadine and astemizole to "allergen immunotherapy," a series of allergy shots to build up immunity to the pollen.
But allergists advise avoidance if possible, by staying indoors in air conditioning between 5 a.m. and 10 a.m., when pollen levels are highest, wearing sunglasses outdoors to protect the eyes from pollen and wearing a mask when mowing grass.
This month, tree pollen counts are waning, but grass polen counts will climb higher.
Oak, ash, alder, sycamore, hickory and walnut trees. Grasses include fescue, velvet timothy, orchard, rye, paspalum, vernal, bent, Bermuda and Johnson grass. Sheep sorel and plantain weeds.
Grasses include June grass, fescue, velvet, timothy, orchard, rye, paspalum, vernal, bent,Bermuda and Johnson grass. Sheep sorrel, plantain and lamb's-quarter weeds abound.
Grasses include June grass, fescue, velvet, timothy, orchard, rye, paspalum, vernal, bent, Bermuda and Johnson grass. Plantain and lamb's-quarter weeds abound.
Grasses include paspalum, bent, Bermuda and Johnson grass. Ragweed and lamb's-quarter, pigweed, sage, marsh, elder and cocklebur weeds. Tree and plant molds begin.
Bermuda and Johnson grass hold out until summer's end Pigweed, sage,marsh elder, cocklebur weeds and tree and plant molds continue.