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This Year's Bay Area Pollen Season Is Really Bad. Here's Why

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Canyon live oak tree in the San Francisco Botanical Garden on May 17, 2019.  (Lindsey Moore/KQED)

The Bay Area has gotten well and truly soaked this year, with some cities near or already surpassing their average rainfall for the entire water year.

But what’s good for our water supply can be a pain in the ear, nose and throat for allergy sufferers. All that rain means more plants growing, which also means more pollen, the fine powder produced by plants’ reproductive organs, called the stamen. Pollen is the cause of most seasonal allergies, and the pollen count indicates how much of it is floating around in the air.

“This pollen season was particularly bad because it rained so heavily and abruptly stopped, and everything pollinated,” said Dr. Michelle Huffaker, of the Allergy and Asthma Medical Group of the Bay Area. “We experienced an overlap between trees and grasses, with really high burdens of pollen each. That was particularly bad for folks’ symptoms.”

For the 7.8% of U.S. adults that suffer from hay fever, that means sneezing, congestion, watery eyes and general discomfort, according to the American Academy of Allergy, Asthma, and Immunology, not to mention legions of sneezing, congested, watery-eyed and generally discomforted sufferers.

Bay Area Pollen Forecast[/aside

Daniel Mackey, 56, a resident of San Francisco, has struggled with pollen allergies for 20 years. “I’ve never suffered as badly as I did this year,” Mackey said.

Ordinarily, he buys loads of antihistamine when his allergies act up, typically in April. That’s usually enough to keep his symptoms at bay.

“This year has been far more difficult,” he said. “It just makes your life unmanageable. It does seem to be getting increasingly worse each year, but this year was particularly bad.”

For children with difficult-to-control asthma or people that don’t have access to inhalers,  medication and other treatment, a bad reaction could mean a trip to the intensive care unit. Although rare, the most dire allergy attacks can be life-threatening.

Is Global Warming Making Your Allergies Worse?

Here’s the long-term outlook: Pollen season is starting earlier and lasting longer. That alone could spell trouble for allergy sufferers. But in addition, plants are producing more pollen, so not only is the season lengthening, it’s also more severe.

One reason for this unwelcome shift is that climate change is pushing temperatures higher, according to researcher Lewis Ziska, a plant physiologist with the U.S. Department of Agriculture’s research service.

“Bottom line, there is a clear effect of temperature increasing the length of the season but also increasing the intensity,” Ziska said.

The negative trend in pollen would seem to extend well beyond the Bay Area, according to a recently published retrospective study in Lancet Planet Health. The study, on which Ziska was the lead author, analyzed at least 20 years of pollen data from 17 locations across the Northern Hemisphere. Twelve of the 17 areas experienced increases in annual pollen count, and 11 of 17 endured a longer season.

Additionally, a 2014 study published in the journal PLOS One suggested that elevated levels of carbon dioxide can increase the amount of pollen some plants produce, by as much as 50% per flower.

The researchers, from Harvard and the University of Massachusetts, Amherst, estimated that grass pollen, the scourge of many Bay Area allergy suffers, will increase by up to 200%.

“We are concerned about the future; if we consistently see temperature changes, that [is] going to mean enormous consequences in terms of allergy season and for people’s health,” Ziska said.


That future may have already begun, according to Dr. Kari Nadeau, director of the Sean N. Parker Center for Allergy and Asthma Research at Stanford University.

“I see both adults and kids,” Nadeau said. “I’ve seen a lot more people come in with very severe symptoms. People calling me in the middle of the night just saying they can’t stop sneezing, and they can’t stop coughing and having mucus congestion. That is different than 10 years ago.”

Spikes Througout the Year

The Bay Area experiences three pollen spikes throughout the year, says Nadeau.

Juniper bushes and cypress, cedar and other trees release pollen beginning in January.

Pollen from annual grasses increases in April and into June, followed by a surge in summer weed pollen. While the ragweed pollen count jumps during the fall months on the East Coast, it’s not as much of a problem in California.

Nadeau added that experts typically know the contours of allergy season, with some variation each year. But even that’s changing. “The problem is there’s more and more of these plants that are now secreting these pollen,” Nadeau said.

San Francisco resident Mackey said his allergies have put a crimp in what is normally an upbeat time of year.

“At the advent of spring, normally people are happy,” he said. “For me, it’s a trial for a few weeks. It’s one of those things that you have to experience to know how debilitating it is.”

You can find resources for dealing with hay fever and information about allergies at the American Academy of Allergy, Asthma and Immunology’s virtual allergist and the web site of the American College of Allergy, Asthma, and Immunology.

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