How Does the Pollen Count Work?

While you probably know that pollen is to blame for your congestion, burning eyes, and scratchy throat, there's a lot more to these little grains, which are actually hard at work at fertilizing plants. Although most allergies are caused by airborne pollen, not all of that is allergenic. Certified pollen experts around the world count and identify pollen grains, often on a daily basis, so that those with allergies can know what's floating around outside and how much of it

there is. Pollen looks like powder because it consists of lots of tiny grains. These grains are the male gametophytes of ants that produce seeds. These grains can be as small as ten micrometers or as large as a hundred micrometers, which still means they're all microscopic. Just a fingertipful collected from the hood of your car could contain thousands of pollen grains. These tiny grains, which produce sperm, are needed for fertilization. We spoke with Dr Estelle Leviton, professor and

chair of Biological Science at the University of Tulsa. She's also a member of the Aerobiology Committee that oversees the National Allergy Bureau, which is part of the American Academy of Allergy, Asthma, and Immunology. Leviton explains that without pollen, we wouldn't have seeds or fruit or grains. In flowering plants, pollen must be transported from the male parts of the plant, the anthers where the pollen is produced, to the carpal, the female part of the plant that produces the ovules.

Pollen can be transported by animals like bees and butterflies, or by the wind. Leviton said. Wind pollinated plants are small and inconspicuous and produce large amounts of lightweight pollen that's easily carried by wind. Insect pollinated plants tend to be large and showy. They often have brightly colored petals, are fragrant and produce nectar. Generally, airborne pollen is from those wind pollinated plants and is the kind that attacks

those of us with allergies. If you tune into a television weather forecast during pollen season, you'll likely hear people talk about the day's pollen count. You may be even wondered whether the count was some sort of estimate of air quality. Literally counting microscopic grains of pollen every day might sound a little bit ridiculous, but that's actually just the beginning of what's happening. The pollen count is the number of pollen grains in a cubic meter of air

over a twenty four hour period. To measure it, pollen is captured by a volumetric air sampling instrument. There are two types of these instruments, rotating arm impactors like the rotorode sampler, and hearst type spore traps like the buck Art sampler. They are both volumetric, but they operate on different principles, and microscopic analysis is needed to analyze both

type of samples. The rotating arm version has a head that spins at two thousand, four hundred revolutions per minute while it spins two small greased rods dropped down, capturing pollen and fungal spores. These rods are placed into a special microscope adapter and examined. The hearst type instrument, on the other hand, has a section trap that sucks in air and particles that adhere to a greased microscope slide inside.

In this case, the slide moves toward the intake orifice at two millimeters per hour, so it's possible to see what was swirling through the air hour by hour during examination using one of the volumetric air sampling instruments. Some pollen stations sample air and collect pollen three hundred and

sixty five days a year. Other stations run samples on week days or only collect three days a week, but not every city or town has the ability to count pollen, and pollen stations are operated in a variety of ways. Some are run by the city or county public health departments,

others by allergists. For example, in Metroid, Alanta, a city with a lot of green space and a notoriously high pollen count, certified counters from Atlanta Allergy and asthma, get up early and physically count the number of pollen particles on the glass slide from a hearst type instrument that's been outside for the prior twenty four hours. That number is what Atlanta residents may here reported by various news outlets. Leviton explained a few stations are run by academics like

me who study airborne pollen as a research topic. It takes training to learn the morphology of pollen, and it takes time to analyze air samples. Certification in pollen counting is available through a few organizations. The process requires pollen counters to take an approved pollen and spore identification course, pass a written exam, and pass a pollen grain and fungal spore identification test, which means that the counters have

to learn the microscopic morphology of individual pollen grains. The training and pollen identification is critical because just counting pollen isn't enough. After all, not everyone is allergic to the same things. Pollen counts also include data on what types of pollen are heaviest in the air. That is, what types of trees, weeds, and grasses are pollinating that day.

People can undergo allergy testing to determine which plants pollen irritates them and use the specific information from morning counts to learn how they might be impacted during the day. Pollen may be to blame for months of discomfort, but remember it also has an important job. It gives us our daily bread by way of fruits, grains, and seeds, and it has a lot of other neat applications too. Levidon says that pollen is used in forensic science because

it can help determine where an object originated. Archaeologists also examine fossil pollen to study which plants early human society is used, and geologists use it to determine the composition of ancient plant communities. Exploration geologists even use fossil pollen to help locate oil deposits. Today's episode was written by Carrie Whitney, PhD and produced by Tyler Clang. Brain Stuff

is a production of iHeartMedia's how Stuff Where. For more on this and lots of other blooming topics, visit our home planet, how stuff works dot com, and for more podcasts from my heart Radio, visit the i heart Radio app, Apple Podcasts, or wherever you listen to your favorite shows,