Children with asthma living in and around Los Angeles have not demonstrated an increase in allergy diagnoses in the onset of climate change, according to findings presented at the American College of Allergy, Asthma and Immunology 2021 Annual Scientific Meeting.

The findings run counter to researchers’ expectations that climate change, which is partially responsible for longer growing seasons of certain plants and larger pollen loads in the air, would cause a rise in the diagnosis of allergies.

“We were somewhat surprised at the results as we expected there would be an increase in the number of kids with asthma who were sensitized to pollen and other allergens,” said Kenny Kwong, MD, principal investigator of the study, in a press release. “Between 80-90% of children with asthma have allergy triggers, which is why it’s important for children with asthma to be tested for allergies. Allergy triggers can cause asthma flares in children.”

The researchers conducted a retrospective cohort study of 5,874 children diagnosed with asthma and living in the greater Los Angeles area to determine whether the children experienced a greater sensitization to seasonal and perennial allergens from 1999 to 2014.

Kwong and colleagues performed a total of 123,209 tests on the children. Testing consisted of skin-prick tests for cat, dog, dust mite, cockroach, grass and weed pollen and tree pollen allergies. The researchers then calculated the percentage of positive tests for the entire time period.

Over the entire 15 years, the researchers reported, there was no increase in the prevalence of any specific allergy.

“Although temperatures have been rising and pollen loads increasing, if someone is not genetically predisposed to allergies, they are not likely to be sensitized to more allergens,” Lyne Scott, MD, an allergist and a co-author of the study, said in the press release. “The growing season is year-round in LA and people with allergies who are already sensitized to pollens suffer more intensely when the growing season is longer, or the air quality isn’t good. It is important to remember that sensitization does not equate to severity so those with allergies may have worse symptoms.”