Pollen collects on the surface of a fishing pond Tuesday at Pettengill Park in Auburn. Steve Collins/Sun Journal

There is a growing public health threat in Maine from pollen exposure driven by the climate crisis, a new air quality report by the state Department of Environmental Protection warns.

“Pollen health threats are real and are increasing in response to warmer temperatures and higher carbon dioxide levels,” according to the May 19 assessment of Maine’s air monitoring network by the department’s Bureau of Air Quality.

“Climate change is lengthening the ‘pollen/mold season’ in Maine,” the report said, “resulting in increased exposure” and “more frequent allergic reaction episodes amongst those afflicted with respiratory disease.”

Giant ragweed, one of the biggest sources of pollen across the country. U.S. Fish & Wildlife Service

The report, a five-year review of air quality issues in Maine, said “the potential effects of air pollution on pollen allergenicity are also expected to increase as the intensity, frequency and duration of air pollution episodes increase with a steadily warming climate.”

It’s a conclusion that matches a February study published by the National Academy of Sciences that found “increases in pollen concentrations and longer pollen seasons” since 1990.

It determined that a warming climate “is the dominant driver of changes in pollen season length and a significant contributor to increasing pollen concentrations.”


“The strong link between warmer weather and pollen seasons provides a crystal-clear example of how climate change is already affecting people’s health across the U.S. Climate change is already here in every spring breath we take and increasing human misery,” William Anderegg of the University of Utah School of Biological Sciences told Columbia University.

Lewis Ziska, associate professor of environmental health sciences at Columbia University’s Mailman School of Public Health, the senior author of the report, said, “We still hear about climate change impacts as something in the future, but this study shows that it is already occurring, and there will be health consequences, especially for allergy sufferers.”

White clover U.S. Department of Agriculture

The study on which Anderegg was the lead author found that in less than three decades, the pollen season in the United States has increased by 20 days – because the growing season starts sooner — and that 21% more pollen is present in the air.

“Our results indicate that human-caused climate change has already worsened North American pollen seasons, and climate-driven pollen trends are likely to further exacerbate respiratory health impacts in coming decades,” the report by half a dozen top scientists.

Dr. Aaron Bernstein, interim director of the Center for Climate, Health and the Global Environment at the Harvard T.H. Chan School of Public Health, told Verywell Health recently that the increase in pollen “is a smoking gun of the health risk from climate change that is probably clearer than any other.”

The tiny male fertilizing agent of flowering plants, trees, grasses and weeds that are called pollen can cause sneezing, congestion, runny noses and worse. The overall health impact of more pollen each spring is an area that experts are only beginning to explore.


Last year, one study published by the Journal of the American Medical Association found that in Maryland, the earlier pollen season led to a 17% overall increase in asthma-related hospitalizations.

Horseweed U.S. Fish & Wildlife Service

Its author said the findings should serve as “a wake-up call to public health and medical communities regarding the need to anticipate and adapt to the ongoing changes in the timing and severity of the spring allergy season.”

The new state report said that both allergic rhinitis and allergic asthma are meaningful public health issues, with about 35 million Americans suffering from asthma and 40% of children experiencing allergic rhinitis.

“Despite its pervasiveness, pollen exposure has received very little attention from the public health and air monitoring communities,” the report said.

It said that because “pollen is a naturally occurring substance” it likely gets less attention.

In addition, there is a “perceived lack of severity regarding its health impacts,” the report said, in part because pollen’s impact varies so much “from individual to individual and with a large dependence on the particular pollen species.”

The Bureau of Air Quality said it “plans to stay engaged with, and wherever possible assist in, the efforts of local, state, regional and national health and scientific professionals and organizations seeking to translate the already known health impacts of pollen and a significant lack of pollen monitoring data into an effective and sustained public health action plan, establishment of a national pollen monitoring network and a health intervention strategy.”

Scientists warn that the earth is warming at an alarming pace due mostly to humanity’s continued reliance on the burning of fossil fuels that has steadily increased the amount of heat-trapping carbon dioxide in the atmosphere.

There is a worldwide consensus on the need to reduce sharply the economy’s dependence on oil and natural gas in order to fend off the worst impacts of the growing problem, which is already killing coral reefs, melting ice caps and increasing the severity and frequency of major storms.

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