Allergies in Cincinnati? Here's how we know how much pollen, mold is in the air

Maybe you can't see it, but you sure can feel it: Pollen is in the air. Mold, too. The Southwest Ohio Air Quality Agency knows how much is there because of a spinning device on its roof. That device is a Rotorod sampler, and it collects pollen and mold from the air. One side of an inch-long rod is lightly greased to make it sticky, and the device spins for one minute every 10 minutes. Put under a microscope, the rods reveal "dots" of allergens. On a day last week, the samples showed elm, juniper and cedar trees were already pollinating.