If you suffer from seasonal allergies, you may have noticed that pollen seasons are getting longer and more intense. A new study confirms that this is not a coincidence, but a consequence of human-caused climate change.

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The study, published in the journal PNAS¹, analyzed long-term pollen data from 60 stations across North America from 1990 to 2018.

The researchers found that pollen concentrations increased by 21% and pollen seasons lengthened by 20 days over this period. They also used climate models to estimate the role of climate change in these trends and found that it was the dominant driver of changes in pollen season length and a significant contributor to increasing pollen concentrations.

The study's lead author, William Anderegg, a biologist at the University of Utah, said that these findings reveal that "anthropogenic climate change has already exacerbated pollen seasons in the past three decades with attendant deleterious effects on respiratory health." 

Vermont is not immune to these effects. The Vermont Department of Health states that climate change may increase pollen concentrations and extend pollen seasons in the state by affecting various factors related to plant growth and flowering.

The department also warns that increased pollen exposure can worsen respiratory health impacts such as allergies, asthma, and viral infections.

According to the department, climate change is expected to increase allergenic pollen in the air we breathe, increase mold growth in homes and businesses, and could increase air pollution from sources like wildfire smoke.

The prevalence of asthma among Vermont adults increased by about 50% between 2000 and 2010. Adult asthma prevalence in Vermont has been significantly higher than the national rate since 2007, and was the 5th highest in the U.S. in 2014.

About 57,000 adult Vermonters and 9,600 children report having asthma. Because pollen also affects many Vermonters who do not have asthma, further increases in allergy triggers could have widespread respiratory impacts to Vermonters.

The department advises Vermonters to take steps to protect themselves from pollen exposure, such as checking the daily pollen forecast, avoiding outdoor activities when pollen levels are high, keeping windows and doors closed, using air filters and humidifiers, washing hands and clothes after being outdoors, and consulting a health care provider for allergy treatment options. 

The department also urges Vermonters to take action to reduce greenhouse gas emissions that cause climate change, such as using renewable energy sources, driving less or using public transportation, buying local and organic food, and planting trees and gardens.