At 8 every morning she works, research associate Asha Patel goes up on the roof of Allegheny General Hospital and approaches a green machine that looks something like a large, at-home garbage disposal. From it, she removes a small laboratory slide.

The machine is called a Burkhardt Volumetric Spore Trap, and it measures for 24 hours at a time the amount of tree, grass and weed pollen and mold spores in the air.

It works by sucking air into a kind of clock assembly and feeding the pollen and spores onto the slide. Ms. Patel stains, or colors, the slide, puts it under the microscope and counts the particles that are going to bedevil folks with allergies to those substances.

For five years, AGH has been collecting the data and then passing it on to local media, weather forecasters and the American Academy of Allergy, Asthma & Immunology. The AAAAI then posts it with similar counts from across the United States on its Web site, where individuals can access them.

Now AGH has begun sending the Pittsburgh air count right into the computers of local allergy sufferers who can use it to better prepare themselves for what they may or may not face when they step outside.

"It's an historic piece of data and it tells you what happened ... yesterday, [but] I look at it as a trending piece of information," said Dave Alchier, 52, an electrical engineer from Bakerstown who is allergic to, among other things, trees and ragweed. He has been a regular user of the AAAAI site for some time.

"They send a chart of what has been trending ... like now tree pollen is going up," Mr. Alchier said last week. "It's going to get worse so I make sure I have my allergy medications with me. ...

"I find out the trend, I have my emergency allergy spray I carry all the time this time of year. ...

"I'll just keep an eye on them [the numbers]," he added. "If I know things are going to be bad the next couple days, I'll stay out of the outdoors as much as I can. I'll keep my car windows up, the air conditioner on. I'll just try to stay out from outdoors unless I want to go out.

"And also with that trending, I know if it rains, the pollen count will go down, but the mold count will go up. You have to watch that if you're allergic to mold. I have a slight allergy to mold."

All in all, Mr. Alchier said, "it's a useful tool."

And that's what it's meant to be, said Dr. David Skoner, director of Allergy, Asthma and Immunology at AGH.

"I would use it to say whether they should take certain medications for the next week or not," he said.

"For example, a typical daily medication would be an intranasal steroid spray. The foundation of treatment might be one spray in each nostril once a day. When the counts go up, they might double the dose. They'll do that themselves, monitor the amounts [of allergens] and do it themselves.

"If they're already on two sprays once a day, when the pollen goes up, they would add an antihistamine or Singulair. I might tell them to do that until the counts start heading down again."

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