Extreme Allergies and Global Warming

  • Aileo Weinmann
  • Apr 14, 2010

Unchecked global warming will worsen respiratory allergies for approximately 25 million Americans. As detailed in the National Wildlife Federation’s report Extreme Allergies and Global Warming, many allergy triggers will worsen as a result of climate change unless action is taken to curb global warming pollution and prepare communities for the changes to come.

Worse Spring Allergies

Spring a mixed blessing for allergy sufferers. Tree pollen is the most common trigger for spring hay fever allergies. With spring arriving 10 to 14 days earlier than it did just 20 years ago, pollination is already starting sooner. New maps in the report show projected increases in habitat conducive to more allergenic trees.

Worse Fall Allergies

In the fall, ragweed is projected to thrive and become more irritating under increased carbon dioxide levels. Ragweed plants at today’s carbon dioxide levels are likely produce about twice as much pollen as they would have 100 years ago. The pollen production rate could double again if we keep adding carbon dioxide to the atmosphere.

More Asthma Attacks

Global warming is especially bad news for the millions of asthmatics in the United States whose asthma attacks are triggered by allergens. They will have to cope with more abundant and severe allergens plus likely increases in ground-level ozone pollution, particularly in urban areas. High ozone concentrations can trigger asthma symptoms and make bronchial airways less able to cope with allergens.

More Health Costs

These potential impacts of global warming could have a significant economic impact: allergies and asthma already cost the United States nearly $33 billion annually in direct health care costs and lost productivity.

Local Effects

The report warns that fungal spores, poison ivy and even allergic reactions to bee stings could be on the increase.

  • State “Hotspots” at risk of high increases in allergenic tree pollen: Arkansas, Iowa, Maine, Minnesota, New Hampshire, New York, Pennsylvania, Vermont and West Virginia.
  • State Hotspots at risk of moderate increases in allergenic tree pollen: Connecticut, Illinois, Kentucky, Massachusetts, Mississippi, Tennessee and Wisconsin.
  • Worst Cities in the United States for Asthmatics and for Spring and Fall Allergies

Extreme Allergies and Global Warming

Sixteen states make the “Allergen Hotspots” list for expanding habitat of trees with highly allergenic pollen.


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