US allergy season starting earlier due to global temperature rising, scientists say
As the global temperature has increased in recent years due to climate change, allergy season in the US is starting earlier and the amount of pollen during such periods has increased, leading to worse allergy and asthma symptoms for some – and new symptoms altogether for others, according to scientists.
That trend is projected to increase as average temperatures continue to rise, but could be reversed if humans are able to reduce carbon emissions, allergists say.
“The intensity of the symptoms has increased, which means what used to be responsive to maybe just one pill used sporadically now requires absolutely an allergy pill but also maybe a nasal anti-inflammatory steroid spray as well,” said Dr John Costa, medical director of the allergy and clinical immunology division at Brigham and Women’s hospital in Boston.
Across North America, the length of the pollen season increased by 20 days and pollen concentration increased by 21% between 1990 and 2018, according to a study in the Proceedings of the National Academy of Sciences.
That’s largely due to global warming, the study states.
“You get an increased volume of plant material because the conditions of moisture and warmth are conducive to greater plant growth, and the greater plant growth means that we are going to have more pollen,” Costa explained.
Some of the biggest recent changes in pollen levels in the US have occurred in the south-east and Texas and through some of the midwest, said William Anderegg, director of the Wilkes Center for Climate Science and Policy at University of Utah and an author of the National Academy study.
“Those areas are [where] the springtime is warming pretty extensively … but there is also a lot that we don’t fully understand about why in particular those areas are seeing the biggest trends,” said Anderegg.
One hypothesis is that it is because of local plant species, according to Anderegg.
In Massachusetts, Costa has also seen a significant increase in how many patients he sees. His waiting list used to be about a month, he said. Now his first available appointment is in August.
Jeff Burkett, a 69-year-old St Louis resident, had terrible asthma as a child. He missed much of second grade due to the disease.
He now has fewer problems with it, but in his mid-50s, he suddenly started to develop intense spring allergy symptoms, such as a runny nose, sneezing and itchy, watery eyes. It started with one week; now they last about six weeks, he said.
While an allergy spray, Flonase, has helped control most of the symptoms, he has not been able to find anything that provides relief for his eyes.
“There’s that time in the spring when everybody is excited to get away from winter, and we get sunny days and longer days, and to me that is turning into my least favorite season because I just can’t go outside and enjoy it,” said Burkett, a retired principal who now works as an education consultant.
To reduce symptoms, Costa said it is essential that people take a medication daily rather than wait for symptoms to flare up.
“Allergies are not just itchy eyes or a runny nose; it’s upper airway inflammation. Once something’s inflamed, it’s a lot more work to calm it down,” he said.
Fortunately, Costa said, there are now several effective over-the-counter allergy eyedrops, like Ketotifen and Olopatadine, that were previously only available via prescription.
To address the worsening allergy season, the US also needs more stations to measure the amount of pollen, said Anderegg. Whereas there are thousands of stations which measure ozone and air pollutant levels, some states only have one pollen station or none, he said.
That’s because there has not been enough funding for stations and pollen is more difficult to measure.
“There really is an urgent need for better data for pollen,” Anderegg said. That will help understand which plant “species are changing and who is ending up in the hospital when pollen seasons get bad”.
That data could also help with early warning systems so that people can better anticipate a flare-up with their allergies, he said.
As to what the future holds for allergies, Anderegg is encouraged by reports that the worst-case scenario for climate change is now seen as unlikely.
“Planning for the next five, 10, 15 years, we should expect pollen seasons to continue to get worse,” Anderegg said.
But he is optimistic that society will continue to make progress in reducing carbon emissions and halt that trend.
For Burkett, his allergy symptoms have reached the point where he and his wife planned a trip in April to the North Carolina coast to escape the pollen.
“It’s a brief time of the year, and it’s not something that knocks me down so I can’t do things; it just keeps me from being outside,” said Burkett, who is preparing to retire.
If the flight from pollen works, he said, “I’m going to start looking to increase the time away next year.”