About pollen counts
What is pollen?
Pollens are the tiny, egg-shaped male cells of flowering plants. These microscopic, powdery granules are necessary for plant fertilization. The average pollen particle is less than the width of an average human hair.
Pollens from plants with bright flowers, such as roses, usually do not trigger allergies. These large, waxy pollens are carried from plant to plant by bees and other insects. On the other hand, many trees, grasses and low-growing weeds have small, light, dry pollens that are well-suited for dissemination by wind currents. These are the pollens that trigger allergy symptoms.
What is a pollen count?
Pollen counts are a measure of the amount of airborne allergens present in the air. Counts are compiled by a variety of methods. Pollen counts are reported as grains per cubic meter of air. Certified aeroallergen counters at many universities, medical centers and clinics provide these counts on a volunteer basis as a service to their communities. Allergy Associates of La Crosse has been the certified pollen counter for the greater La Crosse region since the early 1980s.
How do you acquire pollen counts?
Counters use air sampling equipment to capture air-borne pollens. The number of pollen grains collected are then counted and logged. Allergy Associates of La Crosse reports pollen and mold counts from a 24-hour Rotorod air sampler on a roof at Franciscan Skemp Medical Center, La Crosse, WI.
Can weather affect a pollen count?
Weather can influence hay fever symptoms. Allergy symptoms are often minimal on days that are rainy, cloudy or windless, because pollen does not move about during these conditions. Hot, dry and windy weather signals greater pollen and mold distribution and therefore, increased allergy symptoms.
Is the pollen season the same from year to year?
The beginning and ending times of tree, grass and weed pollen seasons are very similar from year to year in the same location. Intensity differs every year based on the previous year's weather, current weather, and other environmental factors.
If a station is several miles from my home, will the counts apply to my area?
It's difficult to provide accurate pollen and spore levels for areas not near a pollen counting station. If the climate and geography are similar, chances are the figures reported by the station are a good indicator of conditions nearby.
What pollens can we expect to see first and what are we experiencing in La Crosse? Here in the North, trees flower in the spring, grasses head out largely in June and weeds make hay fever trouble in late summer. Our tree pollen season comes roughly in this order: maples shed pollen on any warm day in late winter, then elm and cottonweed, cedar/juniper, ash and potent birch trees. There is a rush of everything when May warms up, with potent oak producing some of the largest pollen counts all over the nation, followed here by walnut and hickory. A few days of 70 or 80 degree heat can make a mighty burst of pollination at any time in this sequence.
The City of La Crosse tree population is about 35% maple, 23% hackberry (looks like an elm), 21% ash, fewer honeylocust, basswood and elm—about 18,000 trees in all.
Do you count pollen year-round? Meaningful numbers to report start to appear by April and continue until Oktoberfest in late September—around the time of the first frost. The pollen counts we report are significant for 100 miles or so from the La Crosse Region.
Sources: National Allergy Bureau and Allergy Associates of La Crosse