Climate Change Is Nothing to Sneeze At

It was balmy weather in Orlando for the recent meeting of the American Academy of Allergy, Asthma and Immunology (AAAAI) and World Allergy Organization (WAO) Joint Congress. Farther up the East Coast, a nor'easter dropped over 2 feet of snow in some areas, and yet less than 2 weeks earlier, the temperature in Central Park in New York City was "unseasonably warm" at 76° F. It could not have been staged better for the meeting's theme of "Global Environmental Change and Respiratory Health." Plenary sessions were focused on different facets of this issue.

Nelson A. Rosario, MD, PhD, presented the case for "The Effect of Climate Change on Pollen Allergy and Respiratory Allergic Diseases." Citing an article from the New England Journal of Medicine,^[1] he discussed a number of extreme weather events that adversely affected human health, including the following:

1998: Hurricane Mitch dropped 6 feet of rain on Central America in 3 days, followed by a spike in cases of malaria, dengue fever, cholera, and leptospirosis.
2003: A summer heatwave in Europe contributed to the deaths of tens of thousands and caused wilted crops, abetted forest fires, and melted 10% of the Alpine glacial mass.

There is clear and convincing evidence^[2] that an association exists between the rising global average temperatures and increased atmospheric CO₂ concentrations. Rosario pointed out that ragweed chamber experiments show that pollen counts increase with higher CO₂ concentrations. This is bad news, because ragweed is a highly invasive plant that produces up to a billion grains of pollen per plan. Higher pollen counts mean more sensitization.^[3]

Rosario also noted that there is some evidence that higher ground-level ozone heightens the allergenicity of pollen. Birch trees exposed to higher ozone levels produced pollen that yielded larger skin prick tests compared with control birch pollen.

Gennaro D'Amato, MD, another plenary speaker, has written extensively on the topic of climate change and respiratory health.^[4] He has warned that climate change is causing earlier onset and longer pollen seasons. Compounding that is exposure to hazardous pollutants of which "particle pollution, vehicle exhaust, and ground-level ozone are the most important types." This toxic mixture affects pollen grains such that each larger grain fragments into many smaller ones that are respirable down to the finest branches of the bronchial tree.

Proving that pollution is associated with exacerbations of respiratory disease is not that easy.

It took researchers a while to link asthma flares to diesel particulate exposure among school children in the South Bronx of New York City.^[5] Once they came upon the idea of using air-quality monitors in wheeled backpacks, they were able to uncover the association between elemental carbon (≤ 2.5 micron) and small airways disease.

Rosario discussed a study indicating that 80% of patients implicate climate change as a cause of worsening symptoms.^[6]

As the late, great Dr William Osler said, "Just listen to your patient; he is telling you the diagnosis."

Cite this: Climate Change Is Nothing to Sneeze At - Medscape - Mar 29, 2018.

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