WEBVTT - How Does the Pollen Count Work?

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<v Speaker 1>Welcome to brain Stuff from How Stuff Works. Hey, brain Stuff,

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<v Speaker 1>I'm Lauren Vogelbaum, and as I record this episode, it

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<v Speaker 1>is spring. It's arguably the most beautiful time of the year.

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<v Speaker 1>Weather turns warmer. Festivals around the world celebrate the season

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<v Speaker 1>and the blooming of the trees and flowers it brings.

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<v Speaker 1>It's just a great time to be alive unless you

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<v Speaker 1>are one of the fifty million Americans who has allergies.

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<v Speaker 1>While you probably know that pollen is to blame for

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<v Speaker 1>your congestion, burning eyes, and scratchy throat, there's a lot

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<v Speaker 1>more to these little grains, which are actually hard at

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<v Speaker 1>work at fertilizing plants. Although most allergies are caused by

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<v Speaker 1>airborne pollen, not all of that is allergenic. Certified pollen

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<v Speaker 1>experts around the world count and identify pollen grains, often

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<v Speaker 1>on a daily basis, so that those with allergies can

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<v Speaker 1>know what's floating around outside and how much of it

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<v Speaker 1>there is. Pollen looks like powder because it consists of

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<v Speaker 1>lots of tiny grains. These grains are the male gametophytes

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<v Speaker 1>of ants that produce seeds. These grains can be as

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<v Speaker 1>small as ten micrometers or as large as a hundred micrometers,

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<v Speaker 1>which still means they're all microscopic. Just a fingertipful collected

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<v Speaker 1>from the hood of your car could contain thousands of

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<v Speaker 1>pollen grains. These tiny grains, which produce sperm, are needed

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<v Speaker 1>for fertilization. We spoke with Dr Estelle Leviton, professor and

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<v Speaker 1>chair of Biological Science at the University of Tulsa. She's

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<v Speaker 1>also a member of the Aerobiology Committee that oversees the

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<v Speaker 1>National Allergy Bureau, which is part of the American Academy

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<v Speaker 1>of Allergy, Asthma, and Immunology. Leviton explains that without pollen,

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<v Speaker 1>we wouldn't have seeds or fruit or grains. In flowering plants,

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<v Speaker 1>pollen must be transported from the male parts of the plant,

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<v Speaker 1>the anthers where the pollen is produced, to the carpal,

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<v Speaker 1>the female part of the plant that produces the ovules.

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<v Speaker 1>Pollen can be transported by animals like bees and butterflies,

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<v Speaker 1>or by the wind. Leviton said. Wind pollinated plants are

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<v Speaker 1>small and inconspicuous and produce large amounts of lightweight pollen

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<v Speaker 1>that's easily carried by wind. Insect pollinated plants tend to

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<v Speaker 1>be large and showy. They often have brightly colored petals,

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<v Speaker 1>are fragrant and produce nectar. Generally, airborne pollen is from

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<v Speaker 1>those wind pollinated plants and is the kind that attacks

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<v Speaker 1>those of us with allergies. If you tune into a

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<v Speaker 1>television weather forecast during pollen season, you'll likely hear people

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<v Speaker 1>talk about the day's pollen count. You may be even

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<v Speaker 1>wondered whether the count was some sort of estimate of

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<v Speaker 1>air quality. Literally counting microscopic grains of pollen every day

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<v Speaker 1>might sound a little bit ridiculous, but that's actually just

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<v Speaker 1>the beginning of what's happening. The pollen count is the

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<v Speaker 1>number of pollen grains in a cubic meter of air

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<v Speaker 1>over a twenty four hour period. To measure it, pollen

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<v Speaker 1>is captured by a volumetric air sampling instrument. There are

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<v Speaker 1>two types of these instruments, rotating arm impactors like the

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<v Speaker 1>rotorode sampler, and hearst type spore traps like the buck

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<v Speaker 1>Art sampler. They are both volumetric, but they operate on

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<v Speaker 1>different principles, and microscopic analysis is needed to analyze both

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<v Speaker 1>type of samples. The rotating arm version has a head

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<v Speaker 1>that spins at two thousand, four hundred revolutions per minute

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<v Speaker 1>while it spins two small greased rods dropped down, capturing

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<v Speaker 1>pollen and fungal spores. These rods are placed into a

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<v Speaker 1>special microscope adapter and examined. The hearst type instrument, on

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<v Speaker 1>the other hand, has a section trap that sucks in

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<v Speaker 1>air and particles that adhere to a greased microscope slide inside.

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<v Speaker 1>In this case, the slide moves toward the intake orifice

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<v Speaker 1>at two millimeters per hour, so it's possible to see

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<v Speaker 1>what was swirling through the air hour by hour during

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<v Speaker 1>examination using one of the volumetric air sampling instruments. Some

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<v Speaker 1>pollen stations sample air and collect pollen three hundred and

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<v Speaker 1>sixty five days a year. Other stations run samples on

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<v Speaker 1>week days or only collect three days a week, but

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<v Speaker 1>not every city or town has the ability to count pollen,

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<v Speaker 1>and pollen stations are operated in a variety of ways.

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<v Speaker 1>Some are run by the city or county public health departments,

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<v Speaker 1>others by allergists. For example, in Metroid, Alanta, a city

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<v Speaker 1>with a lot of green space and a notoriously high

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<v Speaker 1>pollen count, certified counters from Atlanta Allergy and asthma, get

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<v Speaker 1>up early and physically count the number of pollen particles

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<v Speaker 1>on the glass slide from a hearst type instrument that's

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<v Speaker 1>been outside for the prior twenty four hours. That number

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<v Speaker 1>is what Atlanta residents may here reported by various news outlets.

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<v Speaker 1>Leviton explained a few stations are run by academics like

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<v Speaker 1>me who study airborne pollen as a research topic. It

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<v Speaker 1>takes training to learn the morphology of pollen, and it

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<v Speaker 1>takes time to analyze air samples. Certification in pollen counting

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<v Speaker 1>is available through a few organizations. The process requires pollen

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<v Speaker 1>counters to take an approved pollen and spore identification course,

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<v Speaker 1>pass a written exam, and pass a pollen grain and

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<v Speaker 1>fungal spore identification test, which means that the counters have

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<v Speaker 1>to learn the microscopic morphology of individual pollen grains. The

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<v Speaker 1>training and pollen identification is critical because just counting pollen

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<v Speaker 1>isn't enough. After all, not everyone is allergic to the

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<v Speaker 1>same things. Pollen counts also include data on what types

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<v Speaker 1>of pollen are heaviest in the air. That is, what

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<v Speaker 1>types of trees, weeds, and grasses are pollinating that day.

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<v Speaker 1>People can undergo allergy testing to determine which plants pollen

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<v Speaker 1>irritates them and use the specific information from morning counts

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<v Speaker 1>to learn how they might be impacted during the day.

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<v Speaker 1>Pollen may be to blame for months of discomfort, but

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<v Speaker 1>remember it also has an important job. It gives us

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<v Speaker 1>our daily bread by way of fruits, grains, and seeds,

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<v Speaker 1>and it has a lot of other neat applications too.

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<v Speaker 1>Levidon says that pollen is used in forensic science because

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<v Speaker 1>it can help determine where an object originated. Archaeologists also

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<v Speaker 1>examine fossil pollen to study which plants early human society

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<v Speaker 1>is used, and geologists use it to determine the composition

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<v Speaker 1>of ancient plant communities. Exploration geologists even use fossil pollen

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<v Speaker 1>to help locate oil deposits. Today's episode was written by

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<v Speaker 1>Carrie Whitney, PhD and produced by Tyler Clang. Brain Stuff

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