Pollen grains observed in aeroplankton of South Europe

A pollen count is a measurement of the number of

pollen Pollen is a powdery substance produced by most types of flowers of seed plants for the purpose of sexual reproduction. It consists of pollen grains (highly reduced Gametophyte#Heterospory, microgametophytes), which produce male gametes (sperm ...

grains in a given volume of

air An atmosphere () is a layer of gases that envelop an astronomical object, held in place by the gravity of the object. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A stellar atmosph ...

. Pollen counts, and forecasts of pollen conditions, are routinely produced and reported to the public because high aerial pollen concentration is associated with increased rates of allergic reaction for those with conditions such as

hay fever Allergic rhinitis, of which the seasonal type is called hay fever, is a type of rhinitis, inflammation in the nose that occurs when the immune system overreacts to allergens in the air. It is classified as a Allergy, type I hypersensitivity re ...

and

asthma Asthma is a common long-term inflammatory disease of the airways of the lungs. It is characterized by variable and recurring symptoms, reversible airflow obstruction, and easily triggered bronchospasms. Symptoms include episodes of wh ...

. The pollen counted are usually identified to

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

; particularly families with hyperallergenic pollen (e.g. grasses, family

Poaceae Poaceae ( ), also called Gramineae ( ), is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos, the grasses of natural grassland and species cultivate ...

) and families that are prevalent in the relevant area. Thunderstorm asthma events as well as mild winters with warmer days lead to increases in pollen counts, while colder winters lead to delayed pollen release. Though not pollen, hyperallergenic fungal spores such as those of ''

Alternaria ''Alternaria'' is a genus of Deuteromycetes fungi. All species are known as major Phytopathology, plant pathogens. They are also common allergens in humans, growing indoors and causing hay fever or hypersensitivity reactions that sometimes lead t ...

'' may be counted as well.

History

In the UK, the public announcement of the pollen count was popularised by Dr. William Frankland, an immunologist. The

National Pollen and Aerobiology Research Unit The National Pollen and Aerobiology Research Unit or NPARU is a research institute in Worcester. It produces the UK's pollen count, and was the world's first pollen forecasting service. History Aerobiology is the study of organic particles and or ...

became the world's first pollen forecasting service in 1983. According to a study by Leonard Bielory, M.D. that was presented to the

American College of Allergy, Asthma & Immunology The American College of Allergy, Asthma and Immunology (ACAAI) is an American professional association of immunologists, asthma specialists and allergists. The organization is headquartered in Arlington Heights, Illinois, United States of Am ...

in 2012,

climate change Present-day climate change includes both global warming—the ongoing increase in Global surface temperature, global average temperature—and its wider effects on Earth's climate system. Climate variability and change, Climate change in ...

s are expected to cause pollen counts to more than double by 2040.

Methods

One method for sampling pollen from the air is the Burkard trap, also known as the seven-day volumetric spore trap, which works by facing towards the wind and drawing in air using a pump. The pollen particles drawn in by the pump are then stuck to a

silicone grease Silicone grease, sometimes called dielectric grease, is a waterproof grease made by combining a silicone oil with a thickener. Most commonly, the silicone oil is polydimethylsiloxane (PDMS) and the thickener is amorphous fumed silica. Using this f ...

-coated tape that is attached to a rotating drum. The drum slowly rotates one turn over the course of seven days while collecting particles. The tape is removed after one week, cut into day-length sections, and these sections are mounted on a microscope slide with

fuchsine Fuchsine (sometimes spelled fuchsin) or rosaniline hydrochloride is a magenta dye with chemical formula C20H19N3·HCl.

-stained gelatine. The fuchsine selectively stains plant material magenta, making the pollen easy to differentiate from bycatch when analysed under a

light microscope The optical microscope, also referred to as a light microscope, is a type of microscope that commonly uses visible spectrum, visible light and a system of lens (optics), lenses to generate magnified images of small objects. Optical microscopes ...

. The tape is typically analyzed in a longitudinal transect to account for circadian differences in pollen prevalence. The number of pollen grains in a given volume of air can then be calculated by entering the pollen counts into a mathematical formula that account for the sampling conditions. An alternative method uses a rotating silicone grease-coated rod, called a rotorod sampler, rather than a Burkard trap. Machines that use a camera paired with computer software to automatically count and identify pollen samples in the field are being developed and tested. This has the potential to save time, standardise data collection, and provide real-time pollen counts without delay.

Metagenomics Metagenomics is the study of all genetics, genetic material from all organisms in a particular environment, providing insights into their composition, diversity, and functional potential. Metagenomics has allowed researchers to profile the mic ...

may be used to circumvent pollen counting entirely. This method has the advantage of facilitating narrower taxonomic identifications than are typically possible with microscopy, but it is more costly.

References

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External links

Daily pollen reports in the US

Daily pollen reports in the UK

Daily and historical pollen counts US
Air pollution

History

Methods

See also

References

External links