Systems Thinking: Untangling Increasing Pollen Allergies

By Linda Fisher Thornton

Large-scale problems usually have more than one cause. When we look for solutions, we need to investigate many different possible variables. Today, I’ll look at multiple causes of increasing allergies to pollen. This issue is of particular concern to me since I live in one of the Top 10 Most Challenging Places to Live With Spring Allergies (Asthma and Allergy Foundation of America).

Why is pollen worse in and near cities?

Why are allergies worse in urban areas? One of the causes is a result of our choices when planning urban areas and may surprise you. It is an unintended consequence of the preponderance of male shrubs and trees in cities. Tom Ogren says that that 99.9 times out of 100 it will be a male tree, and male trees emit pollen (Tom Ogren, NPR, Too Much Pollen? Blame the Males). It seems that the male trees are preferred because they don’t drop seeds or fruit. But what we get instead of dropped seeds or fruit negatively impacts the health of millions of people.

“If you plant trees, look for species that do not aggravate allergies such as crape myrtle, dogwood, fig, fir, palm, pear, plum, redbud and redwood or the female cultivars of ash, box elder, cottonwood, maple, palm, poplar or willow” (Tammie Smith, For Those With Allergies, Here is a Pollen Primer, Richmond Times Dispatch)

How does pollen affect our brains?

One study, published at NCBI, finds that “allergies strain the brain, these results suggest, and key functions from attention to memory diminish the longer the battle rages.”

Another study found that subjects with a history of allergies were more likely to be diagnosed with major depression. (Eric L. Hurwitz, Hal Morgenstern, Oxford, American Journal of Edpidemiology). WebMD also reports that “In one such study, adults with allergic rhinitis (hay fever) were twice as likely to have been diagnosed with major depression in the previous 12 months. In another study, kids who had hay fever at age 5 or 6 were twice as likely to experience major depression over the ensuing 17 years.”

Why is pollen worse each year?

According to ECARF. “The term (seasonal) is no longer used, since many people react to the pollen of more than one flowering plant species and suffer from symptoms not only in the spring, but also in the summer or virtually all year round.”

This Vox video explains another reason why pollen levels are increasing, and what that increase does to human health.

“Seasonal allergies and asthma impose significant health burdens, with an estimated 10–30% of the global population afflicted by allergic rhinitis (or hay fever) and 300 million people worldwide affected by asthma.” (Charles W. Schmidt, Pollen Overload: Seasonal Allergies in a Changing Climate, NCBI, U.S. National Library of Medicine)

Linked Issues

There are many other issues linked to the pollen problem including these:

The Immune System

Allergies are the result of your immune system’s response to a substance… A person becomes allergic when their body develops antigens against a substance. Upon repeated exposure the severity of the reaction may increase.

Allergies and The Immune System, John Hopkins Medicine

Genetics

The allergic diseases are complex phenotypes for which a strong genetic basis has been firmly established.

Romina A. Ortiz and Kathleen C. Barnes, Genetics of Allergic Diseases, National Institute of Health

Pollution

“Pollutants and climate change act as plant stressors, modifying the expression of plant molecules endowed with immunogenic properties, such as those present in pollens.”

Giovanna Schiavoni, Gennaro D’Amato, MD, and Claudia Afferni, The dangerous liaison between pollens and pollution in respiratory allergy, Annals of Allergy, Asthma and Immunology.

Increasing pollen allergies have multiple connected causes that should all be addressed in a broader context. It is easy to see that when we are dealing with systems, no one source or academic discipline can adequately unravel the complete picture.