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ACAAI: Midwestern Oak Pollen Season Growing Longer

Warming trend's effect on oak pollen expected to be statistically significant in five years

THURSDAY, Nov. 16 (HealthDay News) -- A warming trend during the last decades of the 20th century may be causing the Midwest's oak pollen season to start a half-day earlier each year, a trend that might become statistically significant in five years, according to research presented during the annual meeting of the American College of Allergy, Asthma & Immunology in Philadelphia.

Gregory G. Pendell, M.D., of Children's Mercy Hospital in Kansas City, Mo., and colleagues took daily counts of oak pollen trapped on an inner-city Kansas City hospital roof from February to November, and from 1997 through 2006.

The researchers found that April 5 was the mean day for the oak pollen season's start, meaning the first day 1 percent of the total pollen count was gathered. The pollen season's earliest start was on the year's 74th day, while the latest was on its 109th day. The season's mean launch date between 1997 and 2001 was at 99 days, versus 91.8 days between 2002 and 2006.

The results demonstrate that "oak pollen season appears to begin a half-day earlier each year," the authors note in a statement. "These results indicate a trend to an earlier oak pollen season in the Midwestern U.S. that should reach statistical significance in the next five years."

For more information, go to the Web site of the ACAAI's annual meeting (More Information).

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