Despite Climate Change, Kids with Asthma in Los Angeles Didn’t Have an Increase in Allergy Diagnoses

Study showed no increase in allergic sensitization over 15 years, in more than 5,000 kids with asthma

NEW ORLEANS (November 5, 2021) – Studies have shown that climate change has been partly responsible for longer growing seasons and larger pollen loads, leading to speculation of an increase in sensitizations to environmental allergens. A new study being presented at this year’s American College of Allergy, Asthma and Immunology (ACAAI) Annual Scientific Meeting followed 5874 kids with asthma in Los Angeles for 15 years and found no increase in allergic sensitizations. When your immune system becomes sensitized to an allergen (an otherwise harmless substance), you will likely develop symptoms of an allergy each time you are exposed to that same allergen.

“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. “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.”

A total of 123,209 tests were performed on the more than 5,000 patients. All patients received skin prick tests to dust mites, cat, dog, cockroach, tree pollen, grass pollen, and weed pollen. In addition, all patients had been diagnosed with asthma and allergic rhinitis by an asthma specialist using history, physical examination, and spirometry when age appropriate.

“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,” said allergist Lyne Scott, MD, ACAAI member and co-author of the study. “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.”

High pollen counts don’t necessarily mean that individual sufferers will be affected. There are many types of pollen — from various kinds of trees, from grass and from a variety of weeds. As a result, a high overall pollen count doesn’t always indicate a strong concentration of the specific pollen to which individuals are allergic.

Abstract Title: No increase in inhalant allergen sensitization among Los Angeles asthmatic children over 15 years (Editor’s note: The number “12” in the original title was a typo. 15 is the correct number to be used.)
Presenter: Paula Mohyi, MD

For more information about asthma, or to find an allergist in your area, visit The ACAAI Virtual Annual Meeting is Nov. 4-8. For more news and research from the ACAAI Scientific Meeting, go to our newsroom - and follow the conversation on Twitter #ACAAI21.


The ACAAI is a professional medical organization of more than 6,000 allergists-immunologists and allied health professionals, headquartered in Arlington Heights, Ill. The College fosters a culture of collaboration and congeniality in which its members work together and with others toward the common goals of patient care, education, advocacy and research. ACAAI allergists are board-certified physicians trained to diagnose allergies and asthma, administer immunotherapy, and provide patients with the best treatment outcomes. For more information and to find relief, visit Join us on Facebook, Pinterest and Twitter.

Back to Newsroom

Back to Top