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Frequently Asked Questions About Pollen Forecasting And Sampling for Allergy Alerts

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Tell Me About Pollen Counting

What is a pollen count?
A pollen count is a measurement of how much pollen is in the air. This count represents the concentration of all the pollen (or of one particular type, like ragweed) in the air in a certain area at a specific time. It is expressed in grains of pollen per cubic meter over a 24 hour period.

How is pollen counting done?
A pollen sample is taken using an air-sampling device. These samplers collect particles from the air onto a transparent, sticky surface. The sample is then examined under a microscope, where the pollen grains are counted and identified. The result of this is the pollen count. Since pollen travels long distances through the air, this count is relevant to a large area, and a count from one sampling site is typically used as data for an entire city.

How long does it take to get a pollen sample?
It may sound easy, but pollen sampling can be time-consuming and expensive, sometimes requiring hours of work, and quite a bit of experience or training.

Where should the sampling devices be located?
The best location for a pollen sampler is on a rooftop, several stories from the ground. Rooftop placement provides an open space away from direct exposure to nearby vegetation, as well as protection from vandalism and theft. Elevation of the sampler allows it to collect pollen from a larger surrounding area. Poor placement of the sampler is near biases, contaminants, or obstructions. Locations near air ducts, under over-hanging tree branches, or next to a wall are also examples of poor sampler placement.

Who is responsible for the pollen counts?
Allergists, government agencies, educational institutions, private physicians, and commercial research companies.

What is the purpose of pollen counting?
Allergy sufferers may find it desirable to follow changes in the pollen counts. They will learn much more about which allergens are affecting them, and to what degree. Pharmaceutical companies need the information in their drug research. Allergy researchers need the information to find new trends between symptoms and allergy-inducing conditions. And, people that study plants also need the pollen data to learn more about growth stages and plant habitats throughout the Earth's history.

What is a pollen forecast?
A pollen forecast is a prediction of what the pollen levels will be in the future, like a weather forecast. Pollen forecasting often has greater value for allergy suffers than a pollen count, because they can use this information to plan their day, including whether or not to take medication. Typically, pollen counts show what was in the air several days earlier, not what's going to happen today or tomorrow. Pollen forecasting methods consider natural events, besides the recent pollen counts, that will affect future pollen levels. We consider historical pollen counts (which provide predominant pollen and seasonal trend information for a certain area) temperatures, precipitation, and weather forecasts. Pollen forecasts are geographically specific down to the city.

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