Editing Pollen (section)

==Allergy to pollen==
{{see also|Allergy season}}
{{multiple issues|section=yes|{{More citations needed section|date = March 2013}}}}
[[File:Pine releasing pollen into the wind in Tuntorp 4.jpg|thumb|A [[Pinus sylvestris|pine]] releasing pollen into the wind]]
[[Allergic rhinitis|Nasal allergy]] to pollen is called [[pollinosis]], and allergy specifically to grass pollen is called [[hay fever]]. Generally, pollens that cause allergies are those of anemophilous plants (pollen is dispersed by air currents.) Such plants produce large quantities of lightweight pollen (because wind dispersal is random and the likelihood of one pollen grain landing on another flower is small), which can be carried for great distances and are easily inhaled, bringing it into contact with the sensitive nasal passages.

Pollen allergies are common in polar and temperate climate zones, where production of pollen is seasonal. In the tropics pollen production varies less by the season, and allergic reactions less.
In northern Europe, common pollens for allergies are those of [[birch]] and [[alder]], and in late summer [[Artemisia vulgaris|wormwood]] and different forms of [[hay]]. Grass pollen is also associated with [[Asthma|asthma exacerbations]] in some people, a phenomenon termed [[thunderstorm asthma]].<ref>{{cite journal |last1=Erbas |first1=B. |last2=Jazayeri |first2=M. |last3=Lambert |first3=K. A. |last4=Katelaris |first4=C. H. |last5=Prendergast |first5=L. A. |last6=Tham |first6=R. |last7=Parrodi |first7=M. J. |last8=Davies |first8=J. |last9=Newbigin |first9=E. |last10=Abramson |first10=M. J. |last11=Dharmage |first11=S. C. |title=Outdoor pollen is a trigger of child and adolescent asthma emergency department presentations: A systematic review and meta-analysis |journal=Allergy |date=August 2018 |volume=73 |issue=8 |pages=1632–1641 |doi=10.1111/all.13407 |pmid=29331087 |doi-access=free|hdl=11343/283486 |hdl-access=free }}</ref>

In the US, people often mistakenly blame the conspicuous [[goldenrod]] flower for allergies. Since this plant is entomophilous (its pollen is dispersed by animals), its heavy, sticky pollen does not become independently airborne. Most late summer and fall pollen allergies are probably caused by [[ragweed]], a widespread anemophilous plant.<ref>{{cite web|last1=Oder|first1=Tom|title=Dear allergy sufferers: Don't blame goldenrod|url=http://www.mnn.com/health/allergies/stories/dear-allergy-sufferers-dont-blame-goldenrod|website=mnn.com|publisher=Mother Nature Network|access-date=18 July 2016}}</ref>

[[Arizona]] was once regarded as a haven for people with pollen allergies, although several ragweed species grow in the desert. However, as suburbs grew and people began establishing [[irrigation|irrigated lawns and gardens]], more irritating species of ragweed gained a foothold and Arizona lost its claim of freedom from hay fever.

Anemophilous spring blooming plants such as [[oak]], [[birch]], [[hickory]], [[pecan]], and early summer [[grass]]es may also induce pollen allergies. Most cultivated plants with showy flowers are entomophilous and do not cause pollen allergies.

Symptoms of pollen allergy include [[Sneeze|sneezing]], itchy, or runny nose, [[nasal congestion]], red, itchy, and watery eyes. Substances, including pollen, that cause allergies can trigger asthma. A study found a 54% increased chance of [[asthma]] attacks when exposed to pollen.<ref>{{Cite journal|date=2015-09-01|title=Allergy and asthma: Effects of the exposure to particulate matter and biological allergens|journal=Respiratory Medicine|language=en|volume=109|issue=9|pages=1089–1104|doi=10.1016/j.rmed.2015.05.017|issn=0954-6111|last1=Baldacci|first1=S.|last2=Maio|first2=S.|last3=Cerrai|first3=S.|last4=Sarno|first4=G.|last5=Baïz|first5=N.|last6=Simoni|first6=M.|last7=Annesi-Maesano|first7=I.|last8=Viegi|first8=G.|author9=HEALS Study|pmid=26073963|s2cid=205000320|doi-access=free}}</ref>

The number of people in the United States affected by hay fever is between 20&nbsp;and&nbsp;40&nbsp;million, including around 6.1 million children<ref>{{Cite web|title=Allergy Facts {{!}} AAFA.org|url=http://www.aafa.org/allergy-facts|access-date=2021-07-12|website=www.aafa.org|language=en}}</ref><ref>{{cite journal |last1=Skoner |first1=David P. |title=Allergic rhinitis: Definition, epidemiology, pathophysiology, detection, and diagnosis |journal=Journal of Allergy and Clinical Immunology |date=July 2001 |volume=108 |issue=1 |pages=S2–S8 |doi=10.1067/mai.2001.115569 |pmid=11449200|doi-access=free }}</ref> and such allergy has proven to be the most frequent [[allergic response]] in the nation. Hay fever affects about 20% of Canadians and the prevalence is increasing.<ref>{{cite journal|last1=Sierra-Heredia|first1=Cecilia|last2=North|first2=Michelle|last3=Brook|first3=Jeff|last4=Daly|first4=Christina|last5=Ellis|first5=Anne K.|last6=Henderson|first6=Dave|last7=Henderson|first7=Sarah B.|author-link7=Sarah B. Henderson|last8=Lavigne|first8=Éric|last9=Takaro|first9=Tim K.|date=August 2018|title=Aeroallergens in Canada: Distribution, Public Health Impacts, and Opportunities for Prevention|journal=International Journal of Environmental Research and Public Health|volume=15|issue=8|page=1577|doi=10.3390/ijerph15081577|pmc=6121311|pmid=30044421|doi-access=free}}</ref> There are certain evidential suggestions pointing out hay fever and similar allergies to be of [[Hereditary disease|hereditary origin]]. Individuals who suffer from [[eczema]] or are [[asthma]]tic tend to be more susceptible to developing long-term hay fever.<ref>[http://www.webmd.com/allergies/living-with-allergies-10/rhinitis Allergies and Hay Fever] WebMD. Retrieved on 2010-03-09</ref>

Since 1990, pollen seasons have gotten longer and more pollen-filled, and climate change is responsible, according to a new study.<ref>{{Cite journal|last1=Anderegg|first1=William R. L.|last2=Abatzoglou|first2=John T.|last3=Anderegg|first3=Leander D. L.|last4=Bielory|first4=Leonard|last5=Kinney|first5=Patrick L.|last6=Ziska|first6=Lewis|date=2021-02-16|title=Anthropogenic climate change is worsening North American pollen seasons|journal=Proceedings of the National Academy of Sciences|language=en|volume=118|issue=7|pages=e2013284118|doi=10.1073/pnas.2013284118|issn=0027-8424|pmid=33558232|pmc=7896283|bibcode=2021PNAS..11813284A|doi-access=free }}</ref> The researchers attributed roughly half of the lengthening pollen seasons and 8% of the trend in pollen concentrations to climate changes driven by human activity.<ref>{{Cite web|last1=Boston|first1=677 Huntington Avenue|last2=Ma 02115 +1495‑1000|date=2021-02-18|title=Pollen seasons are getting longer, driven by climate change|url=https://www.hsph.harvard.edu/news/hsph-in-the-news/pollen-seasons-are-getting-longer-driven-by-climate-change/|access-date=2021-07-12|website=News|language=en-us}}</ref>

In [[Denmark]], decades of rising temperatures cause pollen to appear earlier and in greater amounts, exacerbated by the introduction of new species such as ragweed.<ref>Siewertsen, Bjarne. "[http://www.dmi.dk/nyheder/arkiv/nyheder-2015/04/haard-nyser-for-allergikere-i-varm-fremtid/ Hård nyser for allergikere i varm fremtid] {{Webarchive|url=https://web.archive.org/web/20150419165510/http://www.dmi.dk/nyheder/arkiv/nyheder-2015/04/haard-nyser-for-allergikere-i-varm-fremtid/ |date=2015-04-19}}"  (English: Hard sneeze for allergic people in warm future) ''[[Danish Meteorological Institute]]'', 18 April 2015. Retrieved: 19 April 2015.</ref>

The most efficient way to handle a pollen allergy is by preventing contact with the material. Individuals carrying the ailment may at first believe that they have a simple summer cold, but hay fever becomes more evident when the apparent cold does not disappear. The confirmation of hay fever can be obtained after examination by a [[General practitioner|general physician]].<ref>[http://www.allergiesandtreatments.com/pollen-allergy/ Bee, grass pollen allergy symptoms] {{Webarchive|url=https://web.archive.org/web/20091010200012/http://www.allergiesandtreatments.com/pollen-allergy/ |date=2009-10-10}}. allergiesandtreatments.com. Retrieved on 2010-03-09</ref>

===Treatment===
{{main article|Allergic rhinitis#treatment}}
[[Antihistamines]] are effective at treating mild cases of pollinosis; this type of non-prescribed drugs includes [[loratadine]], [[cetirizine]] and [[chlorpheniramine]]. They do not prevent the discharge of [[histamine]], but it has been proven that they do prevent a part of the chain reaction activated by this [[biogenic amine]], which considerably lowers hay fever symptoms.

[[Decongestants]] can be administered in different ways such as tablets and [[nasal spray]]s.

[[Allergen immunotherapy|Allergy immunotherapy]] (AIT) treatment involves administering doses of allergens to accustom the body to pollen, thereby inducing specific long-term tolerance.<ref>{{cite journal |last1=Moingeon |first1=P. |last2=Batard |first2=T. |last3=Fadel |first3=R. |last4=Frati |first4=F. |last5=Sieber |first5=J. |last6=Overtvelt |first6=L. |title=Immune mechanisms of allergen-specific sublingual immunotherapy. |journal=Allergy |date=February 2006 |volume=61 |issue=2 |pages=151–165 |doi=10.1111/j.1398-9995.2006.01002.x |pmid=16409190 |s2cid=36043612}}</ref> Allergy immunotherapy can be administered orally (as sublingual tablets or sublingual drops), or by injections under the skin (subcutaneous). Discovered by Leonard Noon and John Freeman in 1911, allergy immunotherapy represents the only causative treatment for respiratory allergies.