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Speaker 1: Welcome to brain Stuff from How Stuff Works. Hey, brain Stuff,

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Speaker 1: I'm Lauren Vogelbaum, and as I record this episode, it

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Speaker 1: is spring. It's arguably the most beautiful time of the year.

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Speaker 1: Weather turns warmer. Festivals around the world celebrate the season

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Speaker 1: and the blooming of the trees and flowers it brings.

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Speaker 1: It's just a great time to be alive unless you

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Speaker 1: are one of the fifty million Americans who has allergies.

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Speaker 1: While you probably know that pollen is to blame for

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Speaker 1: your congestion, burning eyes, and scratchy throat, there's a lot

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Speaker 1: more to these little grains, which are actually hard at

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Speaker 1: work at fertilizing plants. Although most allergies are caused by

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Speaker 1: airborne pollen, not all of that is allergenic. Certified pollen

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Speaker 1: experts around the world count and identify pollen grains, often

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Speaker 1: on a daily basis, so that those with allergies can

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Speaker 1: know what's floating around outside and how much of it

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Speaker 1: there is. Pollen looks like powder because it consists of

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Speaker 1: lots of tiny grains. These grains are the male gametophytes

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Speaker 1: of ants that produce seeds. These grains can be as

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Speaker 1: small as ten micrometers or as large as a hundred micrometers,

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Speaker 1: which still means they're all microscopic. Just a fingertipful collected

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Speaker 1: from the hood of your car could contain thousands of

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Speaker 1: pollen grains. These tiny grains, which produce sperm, are needed

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Speaker 1: for fertilization. We spoke with Dr Estelle Leviton, professor and

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Speaker 1: chair of Biological Science at the University of Tulsa. She's

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Speaker 1: also a member of the Aerobiology Committee that oversees the

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Speaker 1: National Allergy Bureau, which is part of the American Academy

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Speaker 1: of Allergy, Asthma, and Immunology. Leviton explains that without pollen,

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

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Speaker 1: pollen must be transported from the male parts of the plant,

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Speaker 1: the anthers where the pollen is produced, to the carpal,

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Speaker 1: the female part of the plant that produces the ovules.

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Speaker 1: Pollen can be transported by animals like bees and butterflies,

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Speaker 1: or by the wind. Leviton said. Wind pollinated plants are

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Speaker 1: small and inconspicuous and produce large amounts of lightweight pollen

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Speaker 1: that's easily carried by wind. Insect pollinated plants tend to

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Speaker 1: be large and showy. They often have brightly colored petals,

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Speaker 1: are fragrant and produce nectar. Generally, airborne pollen is from

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Speaker 1: those wind pollinated plants and is the kind that attacks

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Speaker 1: those of us with allergies. If you tune into a

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Speaker 1: television weather forecast during pollen season, you'll likely hear people

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Speaker 1: talk about the day's pollen count. You may be even

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Speaker 1: wondered whether the count was some sort of estimate of

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Speaker 1: air quality. Literally counting microscopic grains of pollen every day

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Speaker 1: might sound a little bit ridiculous, but that's actually just

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Speaker 1: the beginning of what's happening. The pollen count is the

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Speaker 1: number of pollen grains in a cubic meter of air

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Speaker 1: over a twenty four hour period. To measure it, pollen

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Speaker 1: is captured by a volumetric air sampling instrument. There are

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Speaker 1: two types of these instruments, rotating arm impactors like the

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Speaker 1: rotorode sampler, and hearst type spore traps like the buck

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Speaker 1: Art sampler. They are both volumetric, but they operate on

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Speaker 1: different principles, and microscopic analysis is needed to analyze both

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Speaker 1: type of samples. The rotating arm version has a head

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Speaker 1: that spins at two thousand, four hundred revolutions per minute

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Speaker 1: while it spins two small greased rods dropped down, capturing

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Speaker 1: pollen and fungal spores. These rods are placed into a

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Speaker 1: special microscope adapter and examined. The hearst type instrument, on

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Speaker 1: the other hand, has a section trap that sucks in

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Speaker 1: air and particles that adhere to a greased microscope slide inside.

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Speaker 1: In this case, the slide moves toward the intake orifice

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Speaker 1: at two millimeters per hour, so it's possible to see

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Speaker 1: what was swirling through the air hour by hour during

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Speaker 1: examination using one of the volumetric air sampling instruments. Some

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Speaker 1: pollen stations sample air and collect pollen three hundred and

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Speaker 1: sixty five days a year. Other stations run samples on

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Speaker 1: week days or only collect three days a week, but

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Speaker 1: not every city or town has the ability to count pollen,

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Speaker 1: and pollen stations are operated in a variety of ways.

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Speaker 1: Some are run by the city or county public health departments,

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Speaker 1: others by allergists. For example, in Metroid, Alanta, a city

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Speaker 1: with a lot of green space and a notoriously high

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Speaker 1: pollen count, certified counters from Atlanta Allergy and asthma, get

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Speaker 1: up early and physically count the number of pollen particles

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Speaker 1: on the glass slide from a hearst type instrument that's

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Speaker 1: been outside for the prior twenty four hours. That number

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Speaker 1: is what Atlanta residents may here reported by various news outlets.

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Speaker 1: Leviton explained a few stations are run by academics like

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Speaker 1: me who study airborne pollen as a research topic. It

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Speaker 1: takes training to learn the morphology of pollen, and it

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Speaker 1: takes time to analyze air samples. Certification in pollen counting

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Speaker 1: is available through a few organizations. The process requires pollen

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Speaker 1: counters to take an approved pollen and spore identification course,

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Speaker 1: pass a written exam, and pass a pollen grain and

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Speaker 1: fungal spore identification test, which means that the counters have

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Speaker 1: to learn the microscopic morphology of individual pollen grains. The

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Speaker 1: training and pollen identification is critical because just counting pollen

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

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Speaker 1: same things. Pollen counts also include data on what types

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Speaker 1: of pollen are heaviest in the air. That is, what

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Speaker 1: types of trees, weeds, and grasses are pollinating that day.

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Speaker 1: People can undergo allergy testing to determine which plants pollen

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Speaker 1: irritates them and use the specific information from morning counts

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Speaker 1: to learn how they might be impacted during the day.

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Speaker 1: Pollen may be to blame for months of discomfort, but

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Speaker 1: remember it also has an important job. It gives us

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Speaker 1: our daily bread by way of fruits, grains, and seeds,

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Speaker 1: and it has a lot of other neat applications too.

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Speaker 1: Levidon says that pollen is used in forensic science because

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Speaker 1: it can help determine where an object originated. Archaeologists also

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Speaker 1: examine fossil pollen to study which plants early human society

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Speaker 1: is used, and geologists use it to determine the composition

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Speaker 1: of ancient plant communities. Exploration geologists even use fossil pollen

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Speaker 1: to help locate oil deposits. Today's episode was written by

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Speaker 1: Carrie Whitney, PhD and produced by Tyler Clang. Brain Stuff

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