WASHINGTON, March 31 (Xinhuanet) -- Biological materials including dandruff, skin flakes, fur and pollen account for 20 percent to 25 percent on average of air pollutants known as aerosols, justifying them to be a serious factor in climate modeling, German researchers reported on Thursday.

    Aerosols, such as mineral dusts, clay and sea salt, are tiny particles in the air that play an important role in regulating climate. They can absorb heat to warm the air and reflect sunlight to cool it. They also are important in forming clouds and rain.

    But the amount in the atmosphere of aerosols of biological origin, such as bacteria, plant fragments, fur, fungi and similar materials, have been underestimated.

    And now atmospheric scientist Ruprecht Jaenicke of the University of Mainz has found, after a 15-year study of air samples collected from many places around the world, that overall this dust could make up 25 percent of aerosols, and in some places as high as 40 percent.

    The new findings means biological materials should be taken seriously in climate modeling and cloud physics, Jaenicke said.

    He urged other scientists to study the makeup of the "bioaerosoles" so they can set up more accurate climate models. The study is published in Friday's issue of Science. Enditem