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Pollen seasons are shifting and increasing in length

May 27, 2019 04:19PM ● By Editor
From the Minnesota Department of Health - Posted:  May 27, 2019

Depending on the season, pollen is naturally found in the air. Human activities and land-use decisions can increase pollen levels. Increasing evidence suggests that climate change factors, such as warmer temperatures and rising concentrations of carbon dioxide (a potent plant food), are leading to longer pollen seasons. Climate changes may also cause certain trees and plants to produce more pollen.

Ragweed is one of the most common causes of seasonal allergies in the United States. A study updated by Ziska et al., in 2016, found that the ragweed season in Minnesota increased by 18-21 days from 1995-2015.


Growing season length depends on latitude (how far north or south of the equator). Plant hardiness zones provide a standard by which growers can determine which plants are capable of growing at a certain location based on minimum temperatures for that area.

As winters are warming, particularly in Minnesota, plant hardiness zones have shifted to the north, as shown on an Arbor Day Foundation map. These zone shifts may allow non-native, allergenic plants to expand their range into our state. By mid-century, Minnesota’s climate may allow native plants in southern states to grow in Minnesota.

Reducing pollen exposure and impact

Become familiar with the type of pollen that triggers your allergies, so you can prevent or reduce symptoms. You can best manage your exposure by understanding when pollen is especially high in your area and begin taking medication in advance of the season.Your medical provider can help you identify the source of your allergies and determine the best treatment.

  • Be aware of the type of pollen that triggers your allergies and get a pollen and mold report for the Twin Cities area from the National Allergy Bureau.
  • Avoid the outdoors at high pollen times.
  • Use dehumidifiers and air filters indoors.
  • Discuss taking allergy medication with your medical provider.
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