Global warming causing earlier, more intense allergy seasons

MEDWAY, Mass. — In a few weeks, crunch time will begin at the Medway Garden Center. But it didn’t used to be that way.

“When I first started, you wouldn’t sell any outdoor plants until after Memorial Day,” said Joe Avellino. He’s owned the nursery for forty-five years. “But now, people are planting mid-April to late April.”

That may be because they, like Avellino, are seeing signs of an accelerated spring -- botanically.

“The crocuses bloomed almost a month early,” he said. I’ve noticed that a lot of people’s ornamentals -- tulips, daffodils -- are starting to poke through the ground early. I’ve been seeing a lot of the deciduous trees with the buds starting to swell up.”

What’s also swelling up early along with the foliage -- allergy symptoms. And you can blame global warming for that, said Kari Nadeau, MD, PhD, Chair of the Department of Environmental Health at Harvard School of Public Health and a specialist in treating allergies.

“There are these extreme, chaotic conditions that climate change is associated with,” Nadeau said. “And that warming is affecting our pollen seasons.”

For one thing, it’s causing allergy seasons to start earlier.

“Trees are getting the wrong message and they’re releasing pollen earlier in the season,” said Nadeau. “So my patients, for example, otherwise would have started allergy season in March, now they’re having allergy season start January-February. "

Pollen seasons are thus getting longer, she said.

“The warming of our planet is also warming parts of our hemisphere which previously never had those types of warm conditions,” Nadeau said.

That’s creating an environment that can support pollen-producing plants.

“For example, in Canada and parts of Norway, they’re seeing plants like ragweed where it was never allowed to grow before because of the cold conditions,” Nadeau said. “Now it’s warm enough to have ragweed. "

And then there’s the role of carbon dioxide.

“When we have increased greenhouse emissions in our atmosphere, that increases CO2 or carbon dioxide,” Nadeau said. “Carbon dioxide itself unfortunately stimulates plants like those that emit pollen. So grasses and ragweed, in specific, can grow faster. So more pollen is being emitted from any one plant.”

But that’s not all carbon dioxide does. Nadeau said the greenhouse gas also allows pollen to be released more easily from plants.

Allergies can be more serious than many might think, as they can lead to serious infections such as sinusitis or pneumonia.

“People who have allergies have this large problem with mucus congestion,” Nadeau said.

In fact, allergy sufferers can produce up to two gallons of mucus per day, she said -- far above the normal half-cup a day.

“And that’s a lot,” Nadeau said. “And mucus is basically sugar water. Bacteria love sugar and because you’re so exhausted fighting these allergies, people can get viruses, as well.”

But how can anyone be suffering allergy symptoms when, locally, there are barely any plants in bloom? Well, pollen travels -- and it’s going from one globally warmed area of the country to another, said Camellia Hernandez, MD, an allergy doctor at Brigham and Women’s Hospital.

“Pollen actually travels for hundreds of miles,” said Hernandez. “While the trees outside of your own backyard may not be flowering, the trees down a little bit South certainly are.”

That helps explain why, in recent weeks, Hernandez has remained busy.

“It has certainly been one of the warmest winters in New England that we’ve had in a long time,” she said. “And I have certainly seen patients over the last couple of weeks who’ve noticed their spring symptoms have already started.”

But there are also patients she can’t see -- at least not right away.

“Unfortunately there is such a large number of people who are coming in to see allergists now that sometimes our wait times can be backed up even months,” Hernandez said.

Given that reality, Nadeau suggested that, while waiting for an appointment, those suffering from allergy symptoms treat the problem early, in consultation with their primary care doctor, using the many over-the-counter antihistamines and nasal anti-inflammatories available in pharmacies.

She also advised checking daily pollen counts and perhaps avoiding the outdoors when they’re especially high.

This is a developing story. Check back for updates as more information becomes available.

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