Southwest Idaho is located in the northern aspect of the Great Basin of North America. The Great Basin is an arid region consisting of grasslands and sagebrush, with trees such as cottonwood and willows in the river corridors and conifers in the mountains. With agriculture with extensive irrigation, the flora of this region has changed drastically over the last 100 years, introducing new trees, weeds, and crops that have significant allergic potential. Through pollen sampling during the spring (April 1st) to fall (October 31st), the pollen of this region’s allergic plants can be identified. Important allergic plants produce wind-dispersed pollen that adheres to ova resulting in plant seeds and reproduction. A compact sphere of protein and some carbohydrate, this pollen ranges in size from 20-150 microns. These microscopic pollen grains are normally invisible to the human eye, but are common allergy triggers. Our office counts pollen on a daily basis using an electronic device termed a Rotorod. The Rotorod spins one of every six minutes over a 24-hour period and collects the pollen on a greased rod’s surface. Once collected, the rods are stained and the pollen counted by Dr. Callanan or B. Shaddy, L.P.N. Online pollen counts are now available on this website. The pollen data is vital to the understanding of the area allergens. Without such information, formulating an allergy extract for the allergy patient is guesswork. Each season the pollen pattern changes, as it is weather dependent. The spring tree pollen time is especially variable. The heavy rain suppresses the pollen count. Ideal pollen conditions consist of hot, dry, windy weather. The wind disperses high volumes of pollen, resulting in flares of allergy symptoms. These conditions usually occur during the final week of May, producing high counts of grass pollen. Southwest Idaho has a long growing season. The worst allergic pollens are grass in late May and especially the first two weeks of June to the Fourth of July. Plus, high mountain pastures of Timothy can bloom in July. The sagebrush pollen is comparable to grass as a cause of allergy, causing late summer and fall symptoms. Sagebrush pollen peaks from September 15 to October 15 in Boise. The weed season (Russian thistle, ragweed, etc.) is of moderate importance allergenically in August and early September. As in most areas of medicine or science, allergic information is not static. We have been sampling pollen since 1971 in Southwest Idaho. Time and again, new spring pollens that have significant allergic potential do come up!! In closing, I should emphasize the importance of integrating a seasonal allergy patient’s symptoms with direct skin testing and a daily area pollen count. This approach, in conjunction with immunotherapy, offers the best prospect of relief for moderate to severe seasonal allergy symptoms. Visit our home page to see allergy trigger levels. Article adapted from Dr. Callanan’s original article