Urban landscaping to blame in prolonged, crippling allergy season

The allergy season in North America was the longest and heaviest in decades, and experts say the millions of disproportionately male trees planted in urban areas are partly responsible for the high pollen counts.

Why it matters: Prolonged exposure to pollen disrupts the lives of an increasing number of people who develop allergies, which can lead to lifelong treatments for respiratory problems.

Threat Level: The pollen count is heavily influenced by the “botanical sexism” found in urban landscaping, says gardener Tom Ogren to Axios. Trees with male reproductive organs are preferred in areas because they don’t drop messy seed pods or fruit, but instead release pollen at certain times of the year.

  • When female trees that take up pollen are almost absent, landscaped areas can become overrun with masses of pollen in the air.
  • “It’s alarming to me because if we don’t get this under control soon, the air in our cities will no longer breathe,” said Ogren.

What’s up: Immediate symptoms of tree pollen allergy include rhinitis, conjunctivitis, hay fever, allergic asthma, dermatitis, and even anaphylactic shock.

  • In the longer term, this could mean treating asthma, chronic sinusitis, upper respiratory tract infections, nasal congestion, or sleep-related breathing disorders.
  • There are more than 300 million people worldwide with asthma, and that number is expected to increase by 100 million by 2025.

The big picture: The pollen season increased by 20 days annually between 1990 and 2018, while pollen concentrations in North America increased by 21% over the same period, a recent study found.

  • A study published last month found that male trees and shrubs surveyed back in 1998 flooded cities, adding about 6% to the overall allergy index in the US, with increases of up to 20% in Casper, Wyoming, and around almost 15% in the US Minneapolis.
  • Only 8% of forests in 38 US cities and nine international cities were rated “low” for allergies, while more than 51% and approximately 40% of cities had medium and high allergy levels, respectively (as of 2018) by the Municipal Forest Service of Agriculture.
  • Warming temperatures and extreme weather conditions due to climate change, pollution and excess carbon dioxide in the air have exacerbated this problem by extending the pollen production season.

What to see: For years, lawyers, allergist associations, and the federal government have recommended reducing the number of male trees and increasing the number of female trees, which would reduce pollen levels in the community.

  • Some cities like Albuquerque and Berkeley have made pledges or issued pollen control ordinances that require a better ratio of male to female or female-only trees to be planted.

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