Have you ever wondered how pollen is collected and counted?
Clinical Research Institute is the only site in the Twin Cities area that collects and reports daily pollen counts. Other websites give a forecast of the pollen count (low, medium or high) based upon historical and climatological data.
Every weekday, at approximately 7 a.m., two pollen collector rods (small thin plastic rods about the size of a toothpick) are placed in the Rotorod™ Sampler (an outdoor air sampling device). The rods are lightly greased to capture and retain the pollen in the air. The Rotorod™ Sampler spins the rods through the air for 60 seconds every 10 minutes which equals 6 minutes per hour of exposure to pollen. The pollen rods are collected at 7 AM the following morning, resulting in a 24 hour count.
The certified pollen counting specialist at Clinical Research Institute uses a light microscope to count the grains of each type of pollen collected. Pollen grains are identified based on their shape, size and distinguishing features. Counts are reported in pollen grains per cubic millimeter of air. These counts are then posted on our website and recorded on our pollen hotline.
Pollen seasons in Minnesota.
There are typically three pollen seasons in Minnesota, with some overlap of pollen types.
- Tree pollen is present from early April until the end of May.
- Grass pollen is present from early June to mid-July.
- Weed pollen is present from mid June until a hard frost occurs. Ragweed (one of the more allergenic weeds in the area) typically pollinates from early August through mid October.
Outdoor molds can be present year round, with higher concentrations from spring until snow cover again in the late fall/early winter.