At the same time, the researchers also tested area residents, using skin prick testing to assess the levels of sensitization to the five pollens. If someone reacts on a skin prick test, they're said to be sensitized to that substance. However, being sensitized to a substance in an allergy test doesn't always translate to noticeable symptoms, though there's often a correlation between the two.
"We observed a constant increase of the percentage of subjects sensitized to olive, parietaria and cypress, whereas the percentage of subjects sensitized to dust mites remained unchanged over 27 years," Passalacqua said.
Estelle Levetin, a professor of biology who chairs the biological sciences faculty at the University of Tulsa in Oklahoma said that "the data already show that pollen seasons could be longer and pollen levels could be higher, and although this needs more study, it may be that the pollen grain is becoming more allergenic when plants are grown with higher carbon dioxide levels."
This means that people with allergies might need to start taking allergy medications earlier and continue them for a longer period of time, Levetin said. Anyone who feels that their allergies are starting earlier should discuss this with their doctor, she said.
The American Academy of Allergy, Asthma and Immunology offers a city by city look at pollen levels.
SOURCES: Renato Ariano, M.D., director, allergy service, Bordighera Hospital, Italy; Giovanni Passalacqua, M.D., assistant professor, allergy and respiratory diseases, Genoa University, Italy; Estelle Levetin, Ph.D., professor, biology, and chairwoman, Faculty of Biological Science, University of Tulsa, Okla.; March 1, 2010, presentation, American Academy of Allergy, Asthma & Immunology
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