Urban landscaping’s obsession with reducing litter is behind the growing epidemic of pollen-related allergies.

Photo by De’Andre Bush on Unsplash

SPRING and fall are beautiful times of the year. Yet for many, allergies to pollen dull the sense of joy that the rest of us feel as the earth sheds her cloak of winter or when the leaves fall. While spring flowers are the symbols of the season, 70% of the total urban pollen load comes from trees.

No, this is not a natural balance. The increase in pollen started back in 1949 when the US Department of Agriculture promoted the planting of male trees in urban centers to reduce what they called “urban litter.”

Male trees do not bear fruit or drop seeds so they do not create any litter other than leaves. Low litter means a more beautiful city, fewer odours, and safer streets and school yards. This trend surged in 1982 after a booklet by the USDA titled Genetic Improvement of Urban Trees described how male-only trees could be made from species that did not have “sexed” trees. Male trees produce pollen. Without a balance of female trees to trap the pollen, it becomes concentrated in the air.

In the US, pollen-related allergies have risen from 5% of the population to 38% today. And new data show there is a strong connection between overexposure to pollen and increases in heart disease, autism, pneumonia and reflux disease. The question is: Why was this male tree-cloning/low-litter

andscaping trend allowed to flourish without consideration of its impact on human health? It is estimated that people living in urban centres are 20% more likely to suffer from airborne pollen allergies than people living in rural areas. One of the most disturbing outcomes of the low-litter landscaping trend is that many elementary school yards have predominantly male trees. Asthma rates in children have increased by more than 150% since mid-1980; 70% of asthma suffers also suffer from pollen-related allergies.

The Allergy Free School Yard©, founded by Peter Prakke, a retired horticulturist and public educator from Ancaster, Ont., has been instrumental in having school boards implement allergy-free gardening practices, and has helped create allergy-free spaces in Bravery parks across Canada.

The OPALSTM scale is widely used to determine the allergy potential of plants and trees. Developed by Thomas Leo Ogren, author of Allergy-Free Gardening and Safe Sex in the Garden, the 10-point Ogren

Plant Allergy Scale rates 3,000 common trees, shrubs, flowers and grasses. The scale has been embraced by the scientific community and is now used by the American Lung Association and the US Department of Agriculture Urban Foresters. Ogren is currently conducting an allergy audit of the planted urban forests of the five largest cities across Canada, from Vancouver to Halifax.

Low-litter landscaping can have a big impact on our air quality and our health. What can you do to make a change?

Here are a few ideas:
» Know your local pollen index: Check The Weather Network page.
» Get a proper test to help determine what type of pollen allergies you have.
» Plan your time outside; peak dispersal times for pollen tend to be between 5am and 10am
» Check out The Allergy Free School Yard© healthyschoolyards.org.
» Educate yourself about low-allergy plants: Read The Allergy-Free Garden.
» Use the OPALSTM scale as a guide to planting.
» Plant pollen-producing plants away from windows, doors, and vents.
» Ask your local urban planners what they are doing to create more allergy-free green spaces in your city.

More Insight: You might also enjoy this article on seasonal self-care.

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