Kansas City, Mo. ? Researchers at Children’s Mercy Hospital have analyzed a decade’s worth of data and found what appears to be a trend of earlier pollen seasons, which they believe is triggered by rising temperatures.

The group has discovered that during the past 10 years the oak pollen season in Kansas City has begun, on average, a half day earlier each year. The findings were to be presented Saturday in Philadelphia at the annual meeting of the American College of Allergy, Asthma and Immunology.

“It could be creating a longer growing season for oaks,” said Charles Barnes, the Children’s Mercy biochemist in charge of the hospital’s daily mold and pollen counts. “You might have to start taking your allergy medicine earlier.”

The Children’s Mercy research is similar to other research worldwide that attributes earlier, longer and more miserable allergy seasons to global warming.

Some researchers suggest that the growing abundance of pollen may be causing the rising rates of asthma and increases in hay fever, eczema and other allergies in many countries.

The Children’s Mercy data show that the amount of oak pollen in Kansas City increased about 20 percent over the past 10 years.

That increase could be due to warmer weather in spring and summer seasons, Barnes said. The earlier pollen seasons may be due to an earlier return to warm weather in late winter and early spring, he said.

In the late 1990s, oak pollen in Kansas City usually appeared in early April, the Children’s Mercy data show. And although there are variations from year to year, the pollen now is more likely to arrive in late March.