Planet Allergy: Climate Change Fuels Allergies

in Outdoor Allergies
Published: July 2, 2010

670-02310825From the Allergic Living archives. First published in the magazine in 2009.

Wasp sting reactions in Alaska, wildfire pollution, unprecedented mold levels and robust ragweed simply everywhere. Our increasingly warm Earth is a giant hothouse for allergy and asthma triggers that are evolving and expanding. Acting on global warming will not only save our planet – it will spare human health.

In 2006, two men in Fairbanks, Alaska died of anaphylaxis after being stung by yellow jacket wasps. It was the first time anyone had died from an allergic reaction to an insect sting in Fairbanks, let alone two people. That year had already been a particularly bad one for yellow jackets: there were 10 times more wasps than normal, causing school outings to be canceled.

“The sudden abundance of wasps represented an increase in the survivability of the queens over the winter,” explains Dr. Jeffrey Demain, the director of the Allergy, Asthma & Immunology Center of Alaska. He wondered: could global warming be responsible for all these wasps and ultimately, the deaths?

Demain began studying data from his own clinic, the local hospital’s emergency room visits, and the state’s Medicaid program database. He found increases in the number of people seeking medical attention for insect stings in all three databases. When he looked at the Medicaid database broken down by region, he found significant increases in the number of people seeking care for insect stings in all but one region: the gulf coast.

“We then started looking at climate-related variables. And what seemed to fit very closely with this puzzle was a change in temperature,” says Demain.

The five regions that saw many more patients looking for medical attention for insect stings also had at least a 6.1 degree Fahrenheit increase in winter minimal temperature over the past 50 years; the gulf region only had a 1.5 degree increase. And it turns out the gulf coast also already had the highest number of stings per capita and the highest temperature. It was the proof he needed to put the blame squarely on his state’s rising temperatures.

There are plenty of ways in which a warmer Earth can affect allergies and asthma. Allergenic insects move farther afield and thrive in suddenly hospitable climes; CO2, the gas primarily to blame for heating up the atmosphere, causes weeds to flourish and boosts pollen counts in longer growing seasons. Ground level pollution gets worse on hot days, making it difficult for asthmatics to breathe. Not to mention wild swings in weather patterns leading to drought and wildfires in some places, and floods and mold in others.

“All of these are going to affect air quality in ways that can be synergistic and may be contributing to this tremendous increase in allergies and asthma that we’re seeing,” says Dr. Paul Epstein, associate director of the Center for Health and the Global Environment at the Harvard Medical School in Boston.

Dr. Gina Solomon, a senior scientist at the Natural Resources Defense Council and a doctor of internal medicine in San Francisco, notes that “climate change is overall going to have a substantial adverse impact on allergies and asthma. But it will tend to be gradual, and affect different areas differently.”

Evidence of that is already in. From Alaska to Europe, Louisiana to British Columbia, scientists are discovering ways in which climate change is giving our allergy-causing foes a boost. The question is: are we ready to confront these effects of climate change?

Pollen Proliferation

Ragweed is thriving with longer growing seasons.

People who say they are feeling hay fever symptoms sooner in the year and sneezing longer than they used to may be feeling first-hand the effects of global warming. “In the U.S., we’re seeing an early arrival [of spring] of about one week, and persistence of fall another week,” says Epstein. “We see this measured in the flowering of plants and the arrival of birds, and how the trees are responding to the climate.”

An early spring and a late autumn can affect when pollens peak. Dr. Donald Stark, a Vancouver allergist, has been monitoring the pollen counts of trees in his city for more than a decade. In spring, “there has been a two-week shift earlier over 13 years,” he says.

Warmer temperatures in some areas also allow new plants and trees to flourish. Ragweed, which is a fairly recent arrival to Europe, is now a major health concern as it moves into more northern countries on that continent. A study from the Global Allergy and Asthma European Network, which was published in the journal Allergy in April, found that Hungarians are the most affected by ragweed, with about 60 per cent of people there sensitized to the weed. In Denmark, 20 per cent test positive to it.

But it is the north of the northern hemisphere where the consequences of climate change are most dramatic and apparent. “Our temperature change in Alaska is four times that of the global average,” says Demain, who is an adviser to the governor’s sub-cabinet on climate change. “We’re seeing impacts now that others are predicted to see [in the future].”

Next: Compound Pollution: Ozone Assists Pollen