Pollen Count

By staff

What is pollen?

Pollen is a dust-like powder that plants release in order to reproduce. There are two types of pollen: those that are light and are wind-dispersed, and those that are heavy and sticky that are insect-dispersed. Grasses, trees and weeds are examples of plants that reproduce via wind-pollination, and most of these cause most allergic reactions because the airborne pollens can enter our bodies when we inhale.

What is a pollen count?

A pollen count is like a weather report, but instead of the weather, it indicates the concentration levels of all kinds of pollen (weed, grass, and tree pollen) in the air in a particular time in a certain region. It is measured in grains of pollen per square meter of air collected over 24 hours.

Pollens are monitored using a “Rotorod” pollen sampler or any other plastic rod or similar device that is covered with silicone grease. Samples of particles in the air are collected on the rod as the device spins in the air at a controlled speed, usually for a 24-hour period. Afterwards, a trained analyst studies the surface of the rod under a microscope.  Pollens that were collected on the surface are identified and counted. A formula is then used to calculate that day’s pollen count. The media, physicians in the area, and the general public are then informed about the day’s readings.

Values above 76% are considered very high and almost all individuals with sensitivity to these airborne allergens will experience symptoms, and extremely sensitive people may have severe symptoms. Values from 51-75% are still high indicating that most affected individuals will experience symptoms. Values from 26-50% are moderate and indicate that symptoms will be experienced by many, but not all who have airborne allergies. Values from 1-25% are low and only those with extreme sensitivity will experience symptoms. A value of 0 means there is no trace of pollen in the air and symptoms are unlikely to manifest.

Pollen counts are always reported for a past time period and never for what is currently in the air. Depending on the skills of the analysts, some counts may not be as accurate and will reflect the day’s pollen concentration poorly. Some areas may just give a total pollen count that does not give a breakdown of the particular pollens that have the higher or lower count.

In general, on hot, dry and windy days, usually early in the morning, the quantity of pollen dispersed is greater than usual, and they stay in the air suspended for a longer period. Allergy symptoms are higher at these times. On chilly, wet, rainy, or windless days, pollen concentration is lower, and thus less allergy symptoms occur.

What are the benefits of a pollen count?

A pollen count is helpful to individuals who are susceptible to pollen allergies. It can be used as a general guide to assess if they should be ready for the onset of their allergies, and be ready with medications for treatment. They should use the information in planning their activities for the day. If pollen counts are high for any particular pollen, then they should opt to stay indoors.

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