LEBANON — Dr. Erin Reigh — an allergy and immunology specialist at Dartmouth Hitchcock Medical Center — has a general idea of when pollens that trigger allergies come out.

“But maybe it’s actually a little earlier than we think,” Reigh said Wednesday in her office at DHMC before heading up to the Lebanon medical center’s roof where she held a round metal object in her hands.

While the device, known as a drum, is small, it has the potential to affect how patients with seasonal allergies are treated at DHMC.

The device works by filtering air through a pollen collector called a Burkard Volumetric Spore Trap where pollen sticks to the drum, which is coated in a sticky film.

By putting pink stain on the tape and then placing slides under a microscope, Reigh will identify which types of pollen are the most prevalent each day during the week the drum spent in the spore trap.

Knowing when different types of pollen appear is important so that patients know when to start their medication.

Reigh said she often counsels patients to begin their medication a month early.

“That reduces the chance that they flare up when the pollens come out,” she said.

Ash, birch, elm, timothy grass and ragweed are among the most common allergens in the region, she said.

In addition to being able to get data on specific pollens, Reigh will also be able to decipher the concentration of each pollen in the air.

The new pollen counter also will enable providers to tailor allergy testing and treatment for patients — including those who have allergy-induced asthma — based on the airborne pollens that trigger them the most.

Some people require allergy shots to treat their symptoms. Those shots are custom mixed based on the allergens that most affect each patient.

The data coming from the pollen station will enable providers “to match the local pollen so that our shots are more effective,” Reigh said.

Reigh was inspired by her patients to set up a pollen counting station at DHMC and took on the project herself.

“When patients would come in, they would often talk about the pollen,” she said. “I always thought, I would love to be able to answer what they’re saying with some actual data” about what types of pollen are the most active in the Upper Valley.

Currently, Reigh and other DHMC providers rely on data provided by the National Allergy Bureau from a pollen counter around 350 miles away in Rochester, N.Y., to figure out what type of tree, grass and weed pollen is in the air.

But having more localized information “would help me to tailor the things that we’re testing for,” she said. “Maybe we find out that there’s a weed that’s actually really, really prevalent and we’re not testing for it. I would love to know that.”

Once Reigh’s station is fully operational — she is currently in a trial run and hopes to have official data available in October — it will be the National Allergy Bureau’s only pollen counting station in New England. It will run around six months each year, May through October. People will be able to subscribe to Reigh’s reports via https://pollen.aaaai.org/#/.

The National Allergy Bureau is operated by the American Academy of Allergy, Asthma & Immunology, a nonprofit organization with more than 7,100 allergist and immunologist members, according to its website. Known as the AAAAI, the organization helps fund research into allergy and asthma treatment and prevention.

Ideally, pollen counting stations would be set up every 100 miles or so, said Dr. Warren Filley, an AAAAI fellow who helped establish the National Allergy Bureau in the 1990s.

“There isn’t anyone in New England. There really isn’t,” said Filley, who also is a University Of Oklahoma Health Sciences Center clinical professor emeritus and a retired allergist. “I’m really glad that they are having a station there because it’s going to extend the range.”

Unfortunately, it can be expensive. The bureau has dozens of stations throughout the United States, according to its map, but there are parts of the country — like New England — where there is limited data.

“Keeping it up and having someone to count it is an expense,” Filley said during a phone interview. “This is a highly technical skill. You have to know what the pollen looks like, what the mold looks like, how to count it, how to count it accurately.”

Reigh received the equipment needed to set up the pollen counting station for free; she will share her data with AAAAI, where it will available for other researchers.

In order to operate the station, Reigh took a course through the National Allergy Bureau and passed its pollen identification exam. (She got her microscope for free from Dartmouth’s Giesel School of Medicine because they no longer needed it.)

“I’m doing this strictly volunteer. I just am interested in it. And so I’ve I decided to do it. I want to know,” said Reigh, who estimated it would take her around six hours each week to study and identify the pollens. “But not everyone has the luxury to spend time on something like this without a grant or to be paid specifically to do it.”

In some ways, accurate pollen counts have become even more important over the years. Allergy seasons — especially in higher latitude areas — are growing longer.

“There is definitely global warming and it allows the plants to grow over a longer period of time,” Filley said. “As you see climates change, you see plants move in different areas.”

The weather has an impact on which pollens appear when, Dr. Karen Hsu Blatman, one of Reigh’s colleague’s, said in a phone interview earlier this month.

For example, this year’s later-season snow pushed off the start of tree pollen season, which then likely ran into grass pollen season and then weed season, Hsu Blatman said.

She also noted that the summer’s heat and humidity have likely made allergens “more potent.”

Liz Sauchelli can be reached at esauchelli@vnews.com or 603-727-3221.