Maine’s extended drought could be prolonging the fall allergy season, but there isn’t enough data available to confirm a connection, experts say.

During a drought, there is no rain to “wash” pollen out of the air, said Andrea Nurse, a researcher at the University of Maine’s Climate Change Institute. Instead, the pollen released by a common fall weed like ragweed stays adrift longer and travels farther, making it harder for people to avoid.

Drought-related winds can also pick up and recirculate old tree and grass pollens left on top of a parched ground, Nurse said. That old pollen often hitches a ride on fine dust particles that cause respiratory inflammation that makes allergies worse.

Despite these facts, scientists and doctors can’t yet prove whether droughts like the one currently gripping Maine — new federal data shows 93% of the state was in severe or extreme drought as of Tuesday — make seasonal allergies worse.

“It’s a very interesting question that I’ve been trying to answer for 15 years,” said professor Allison Steiner, the head of the University of Michigan’s climate department. “I definitely think so, but right now we just have anecdotes. We don’t have the data.”

Every pollen-producing plant responds to drought conditions in its own way, Steiner said. Rains cause spring trees to produce more pollen, for example, but washes it out of the air faster. On the other hand, a drought limits tree pollen production, but what is released will stick around longer.

Drought is one consequence of Maine’s changing climate that affects seasonal allergies. Warmer temperatures and longer growing seasons, or periods between plant-killing frosts, are leading to longer and more severe seasonal allergy seasons in Maine.

One in four Americans has a seasonal allergy, according to the U.S. Centers for Disease Control and Prevention, which makes it likely that about 325,000 Mainers also suffer seasonal sneezing, runny noses, itchy eyes and scratchy throats.

Although the state does not track how many residents have seasonal allergies, more seem to have developed them in recent years, said Andrew Parker, an allergist with Allergy and Asthma Associates of Maine who practices in the Portland area. Their symptoms also seem to be getting worse, he said.

“With so many potential variables, it is hard to single out one reason for the increase,” Parker said.

Pollen counts are only part of the allergy equation, Parker said. When it’s not raining, people are more likely to be outside, increasing their exposure to airborne allergens even if fewer of them are being released by the trees, grasses and weeds due to drought.

“People’s behavior changes when it’s beautiful out,” he said. “They go outside, where the pollen is. They open windows and let the pollen in. Sometimes you can see the pollen, but not usually. You usually won’t know it until the coughing, runny nose and itchy eyes set in.”

The consequences of inhaling the particulate matter created by wildfire smoke also likely plays a role in Maine’s worsening allergy landscape, especially during drought, Parker said. As of Oct. 2, Maine had reported 747 wildfires, more than the annual totals for the last five years.

In Maine, the biggest pollen producers are trees, which release spores from March to May. Grass pollen counts surge in June and July, state biologists say. Ragweed is Maine’s biggest airborne allergen threat in the fall, releasing pollen from August to October.

The pollen season is now over in northern Maine, but the local allergy season is not, largely due to the recirculation of old pollen, said David Macek, an environmental specialist in the Presque Isle-based environmental health lab of the Mi’kmaq Nation.

His collectors are still gathering old pollen. He can tell it is old because it is out of season, broken and often caked in little bits of dry soil, Macek said. The sensors collect recirculated pollen every year, even when it rains, but the volume of pollen and dust is higher during dry years.

For years, the tribe operated Maine’s only aeroallergen monitoring site. In 2023, the state’s public health and environment agencies installed four aeroallergen sensors: in Augusta, Bangor, Cape Elizabeth and Rumford.

But it will take several years of collecting and analyzing the data from these sensors to know exactly how a drought can affect local tree, grass and weed pollen counts and mold spores, said David Madore, a spokesman for the Maine Department of Environmental Protection.

The state’s climate action plan, Maine Won’t Wait, identified pollen as one of the biggest risks that climate change poses to Mainers’ health, along with rising temperatures, extreme weather, tick and mosquito-borne diseases, and food and water-borne infections.

Maine also faces unique challenges due to its high asthma rate: 12% compared to the national average of 9%, second only to Rhode Island. Asthmatics with prolonged pollen exposure can develop chronic airway inflammation that causes structural changes that make it hard to breathe.

In a Colby College survey published last year, Maine doctors said allergies were among the top six most-common climate-related illnesses reported by their patients, along with asthma, tick-carried diseases such as Lyme disease, heat-related illnesses, COPD and mental health problems.