Reference information: http://www.polleninfo.org
Pollen which appear at unusual times of the annual cycle:
Usually the pollen season starts in spring and ends in late summer / autumn. Some plants however, flower late in the year and release nonetheless considerable amounts of pollen.
Cedars flower in late September / early October and may cause conspicuous yellowish precipitations similar to what we know from pine and spruce in certain years during May.
Ivy pollen becomes airborne in small amounts at about the same time.
different species of the cypress family may flower throughout the year and release some pollen. In the Mediterranean, cypress is sometimes already in December in full flower.
In late autumn one can notice in some years a yellowish dust layer here and there, composed of rust summer spores of Puccinia (black rust or stem rust on wheat).
long - distance pollen transport
During winter time, sand from the Sahara desert is transported by strong winds far north to Europe. We sometimes detect at such occasions very characteristic pollen grains from Ephedra, which flowers in late winter in the Atlas mountains.
In particular in Scandinavia, birch pollen allergic patients must often face surprising hayfever attacks in early spring although no birch is yet flowering far and wide. Long distance transport can deposit lots of birch pollen of southern origin by suitable weather conditions. Ambitious forcast models are under development, combining methods of meteorology, aerobiology and remot satellite sensing.
The information aims to provide educational purpose only. Anyone reading it should consult physician before considering treatment and should not rely on the information above.
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