The effects of climate change — warmer temperatures and longer periods between frosts — are leading to longer and more severe seasonal allergy seasons in Maine.

Rising temperatures cause Maine’s pollen-producing plants to release more of the airborne allergen for a longer period of time, scientists say. Unfortunately, the same fine powder essential for plant reproduction triggers an immune system overreaction when inhaled by someone with seasonal allergies.

“This is our new reality,” said Matt Wellington, associate director of the Maine Public Health Association. “Climate change poses a serious threat to Mainers’ health, whether it’s extreme weather or the increase in tick-borne illness or rising pollen counts. We must adapt.”

Preparation for Maine’s sneezy spring season will soon get easier, however. State officials are preparing to publish localized pollen counts from four newly installed monitors around the state later this year to help people with seasonal allergies decide which days to take cover.

More than one in four Americans suffer from seasonal allergies, whose most common symptoms are sneezing, runny nose, congestion, itchy eyes and scratchy throats, according to the U.S. Centers for Disease Control and Prevention.

The biggest pollen producers in Maine are trees, which release the microspores from March to May. This year, scientists predict Portland and Augusta’s spring allergy season will peak the week of May 10, when Maine’s maple, birch and oak trees all pump out pollen at high rates. Kittery and Caribou, where different tree species are the chief pollen producers, will peak the week before, on May 3.

Grass pollen counts will surge in June and July, when the ryegrass, fescue and sweet vernal varieties release their pollen, state biologists say. Weeds like common ragweed release pollen from August to October. But grass and weeds don’t yield pollen counts as high as during Maine’s spring tree allergy season.

Earlier springs and later falls mean a longer growing season for most plants, including those that produce pollen. In Portland and Presque Isle, the growing season has lengthened by nearly two weeks since 1970, according to Climate Central, an independent research organization.

Maine springs are warmer now, too. The average daily temperature of Portland’s meteorological spring, defined as March, April and May, is now 2.2 degrees Fahrenheit warmer than it was in 1970, according to federal data. Presque Isle’s spring temperature was up 1.5 degrees over the same time period.

Rising levels of carbon dioxide — a key driver of global warming — cause plants to make significantly more pollen. A 2022 University of Michigan study published in Nature Communications predicted a 200% increase in national pollen emissions by the end of the century.

Maine’s future is also expected to be wetter, which may offer some short-lived relief. Rain washes pollen out of the air, and makes it harder to go airborne.

However, heavy rain also breaks up pollen clumps on the ground into fine, easy-to-float particles. Rain also aids in the growth of plants and mold, another common allergen.

The state’s first 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.

“Climate change is making aeroallergens like pollen in the air worse, and the trend is for this problem to continue to increase with a changing climate,” according to a report produced by the team of scientists who advised the Maine Climate Council on the state’s second climate action plan.

Maine also faces unique challenges due to its high asthma rate: 12% compared to the national average of 9%, second only to Rhode Island. The high asthma rate makes prolonged exposure to high pollen levels particularly concerning for public health.

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.

Children are at particular risk, according to Anne Coates, a pediatric pulmonologist at MaineHealth.

Prolonged and intensified allergy seasons not only worsen respiratory conditions like asthma, which is one of the most common reasons why children miss school, but also increase reliance on medications and health care services, Coates said.

Pediatricians like Coates report an anecdotal increase in patients experiencing the telltale symptoms of seasonal allergies: prolonged cough, runny nose, itchy watery eyes and disrupted sleep. She said it’s one of several direct and indirect ways that climate change is harming her young patients.

“Even if children don’t have a formal allergy to these airway irritants, like pollen or mold, they can … be bothered by it,” Coates said. “For those who are allergic to pollen or mold, the severity of the symptoms increases. The severity increases with the length and intensity of the exposure.”

When a child struggles to sleep, other health, developmental and learning problems can arise, she said.

There are many medical problems that can’t be avoided — genetic syndromes or accidents, for example — but Coates points out that the air pollution and burning of fossil fuels that drive climate change are what doctors call a modifiable risk factor, something that can and should be controlled, if not eliminated.

“I care about the health of everyone, but as a pediatrician and as a mother, my lens is on the health of our children,” Coates said. “We can’t turn our heads away from this problem, even if it is tough to solve. If we don’t make really notable changes, our children will feel it. They will suffer.”

But no one can quantify the level of local risk from Maine’s longer pollen seasons, or even confirm how much it has changed over time, because for years, Maine was one of about a dozen states that didn’t have a robust pollen monitoring network.

Without such a network, Maine couldn’t provide the public with timely allergy warnings, like which days Mainers who suffer from seasonal allergies should avoid going outdoors due to high pollen counts, or when they should avoid touching their eyes or nose when outside.

That is about to change. After years of relying on a single pollen monitor in Presque Isle run by the Mi’kmaq Nation, Maine deployed new sensors in 2023 capable of continuously monitoring aeroallergen levels in Rumford, Cape Elizabeth, Augusta and Bangor.

The sensors cost $3,750 each at the time of purchase, but now price out at about $6,000 a unit. In addition, Maine also pays an annual service fee of $2,400 per device. Funding for the network came from a federal Climate-Ready States and Cities Initiative grant awarded in 2021.

These pollen counts will start being posted to the state’s public health tracking network, likely this summer, but residents can already access the data now, for free, by downloading the Pollen Sense app on their smartphone, according to state environment and public health officials.

It took time for state officials to develop their understanding of these new sensors, improve the quality of the data and gain confidence in its accuracy, according to Dave Madore of the Department of Environmental Protection and Lindsay Hammes of the Maine Center for Disease Control and Prevention.

Working with automated data feeds that are updated daily, creating and publishing high-quality data dashboards and ensuring data quality are all labor-intensive and time-consuming tasks, they said. The work is “ongoing, though close to completion,” they said.