For those with allergies, the best time to run or walk outdoors is morning, a new study suggests.
An analysis of pollen data during the spring of 2021 revealed that the lowest counts occurred between 4 a.m. and noon, while the peak counts happened between 2 p.m. and 9 p.m., according to a report presented at the annual meeting of the American College of Allergy, Asthma and Immunology on Thursday.
The findings suggest that “if you are allergic to pollen, you should do your outdoors activity in the early morning hours,” said the study’s lead author, Dr. Stanley Fineman, an allergist with Atlanta Allergy and Asthma.
Although the researchers were only monitoring tree pollens, Fineman believes that the diurnal variation he and his colleagues documented would apply to all pollens.
For the new study, Fineman and colleagues from Emory University used a real time pollen imaging sensor to count pollen at three sites in the Atlanta area between March 24 and March 31 of 2021. They found that pollen levels started to gradually increase at noon from the morning minimums and then peaked in the afternoon and evening.
Fineman recommends that, even if people with allergies go out when the pollen count is low, they should also shed their clothes and shoes as they go inside, tossing the clothing in a washing machine. “It would be ideal to leave your shoes in the mudroom if you have one,” he advised.
Another tip per Fineman: Wash your hair before going to bed since pollen can stick to the strands.
The findings weren’t a surprise to Dr. Merritt Fajt, an allergist and an assistant professor of medicine at the University of Pittsburgh.
“Time of day can definitely influence pollen count, but it’s good to get more details,’ Fajt said. “There are a couple of other things that can influence the count, such as the weather, the temperature and the time of year.”
As the air cools, that can bring pollen grains down in a kind of allergen shower, which helps explain why allergy symptoms can be worse in the middle of the night, Fajt said. “That’s why we tell patients not to sleep with the windows open,” she added.
Weather also makes a difference.
Those with allergies should pay attention to wind speed since gusts can bring in pollen from other areas, Fajt said. And while many think that rain cleans things off, it can actually unearth pollen and cause more to be in the air, she added.
The new information about minimum and peak pollen times can be a good rule of thumb, “but it’s always good to check a pollen tracking app or a pollen counting website before going out to exercise,” Fajt said.
While the new study is “interesting,” and “absolutely makes sense,” it doesn’t tell us whether individuals exercising outdoors will be protected from a flare up of their symptoms, said Dr. Miriam Merad, a professor of immunology and medicine at the Icahn School of Medicine at Mount Sinai in New York.
Merad said she’d like to see a study with joggers going out in the morning compared to the same people going out in the afternoon.
Even though counts are lower in the morning there will still be some in the air and “some people are very sensitive to it,” Merad said. “For those with severe allergies it may not be protective to work out in the morning. But for those who have less severe allergies it may be a way to avoid flares.”
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