Calgary, Alberta (Suburbs)
Due to extreme variations in the weather at this site, the tree pollen season fluctuates significantly from year to year. The pollen seasons described here try to cover the time when each can occur.
Acer sp.- Maple season varies from year to year slightly due to weather. Significant counts are observed from the end of April to the end of May. The season can start from the second week of April to early May and end late May to mid-June. The amount of pollen from the maples varies from one part of the City to the other. The counts at this site can get high compared to the other site.
Alnus sp.- Alder season starts from early March to early April and ends from late June to mid-July. The counts vary from low to moderate due to the number of species present.
Betula sp.- The birch season can start from late April to early May and end early to mid-June. The counts can reach high levels, depending on the year. Some years only low and moderate counts are observed. The seasonal fluctuations are partially attributable to weather.
Populus sp.- The poplar, cottonwood and aspen season can start from mid-March to mid-April and end mid to late May. Some of the counts are very high and may cause allergic reactions.
Cupressaceae family- The cedars, junipers and yews produce some moderate counts from mid-April to mid-May. The season starts ealy to late March and ends late July. Probably of no significance in causing allergic reactions except in individuals who are highly sensitized.
Fraxinus sp.- The ash pollination season is short and can start from late April to early May and end late May to mid-June. Some very high counts are observed. The pollen season and levels can vary a great deal which is partially due to weather. Considered to be allergenic only in highly sensitized individuals.
Pinaceae family- This group includes the spruce, fir and pine trees. Very high counts are observed from late May to late July. The pollen season can occur between early May to the end of July. The season varies from year to year due to weather.
Quercus sp.- The oaks flower for a short period, with low counts and the season generally occurs in the month of May. Two seasons are possible with the second one occuring from mid-May to early June. Oaks can be highly allergenic.
Ulmus sp.- The elm are important allergens. The season can start between late March to early May and can end late April to late May. The seasons can vary not only in when they occur but the amount fo pollen produced from year to year. This is probably mostly due to the effect of weather. The counts are low to moderate and can create allergic reactions.
Salix sp.- The willows pollen season can start from mid-April to the second week of May and end late May to mid-June. The season usually lasts at least a month and can be sporadic. There is some variation in the season from year to year and low to moderate counts are observed.
Gramineae family- The grasses produce significant counts, from low to high range, from late May to early October with the most significant counts occuring in June and July.
Ambrosia sp.- Ragweed season is from the mid-August to mid-September with only very sporadic low counts observed.
Artemisia sp.- The main sagebrush and mugwort season is from late July to early October with low and the occasional moderate counts observed. Can be significant in causing allergic reactions.
Chenopodiaceae & Amaranthaceae- This group of weeds are similar microscopically and are not differentiated. They include some weeds, which are considered allergenic. Occasional moderate counts are observed. The season can start mid-June and end early October. At these levels they may be of no significance depending on species present and the sensitization of individuals.
Plantago sp.- The plantains pollinate from early June to mid-September. The counts are in the low range but may cause allergic reaction in highly sensitized individuals.
Urticaceae sp.- The nettles and parietaria season can start from mid to late June and ends late August. The counts are usually low with the occasional moderate counts. Due to their small size they are considered important allergens.
Diatrypaceae sp.- The counts are sporadic throughout the whole counting season. Very high counts can be observed from late March to mid-October. They are not known to cause allergic reactions.
Erysiphe (Oospora) sp.- Powdery mildew - The main season is from May to mid-October. The counts can get very high. Allergenic properties unknown.
Leptosphaeria sp. & Leptosphaeria look-alikes- These two are grouped together since they are in the same class of fungi and are similar microscopically. The season starts mid-May to the end of September. The counts vary from day to day, which is probably due to the effect of weather. Very high counts are observed from May to mid-October.
Boletus sp.- The season for this spore is very sporadic with some high counts observed. It may be of significance in causing allergic reactions. The season, with significant counts, is July to the end of September.
Coprinus sp.- This mushroom produces moderate and high counts from the end of May to mid-October. It is considered an important allergen.
Ganoderma sp.- The bracket fungus produces moderate and high counts from mid-June to the end of September. It is considered an important allergen.
Uredinales sp.- The rusts produce mostly moderate counts in the main season, but not enough is known about their significance in causing allergic reactions at these levels. The season is from mid-June to mid-October.
Ustilaginales sp.- The allergenic properties of the smuts are unknown. The season, with significant counts, is from June to mid-October with some very high counts from July to the end of September.
Alternaria sp.- The counts are mostly in the moderate range with a few high counts and some species are known to cause allergic reactions. The main season is from Mid-June to mid-October.
Penicillium sp. & Aspergillus sp.- These spores are found throughout the whole counting season and are probably present in significant numbers beyond that. There are significant counts from early March to late fall. Probably significant in causing allergic reactions.
Botrytis sp.- This may be a significant allergen, with very sporadic counts from May to early October.
Cladosporium sp.- The most abundant spore found throughout the whole season. This spore exists all year round but very high counts are known to occur from March to well into late fall. Some species are known to cause allergic reactions.
Epicoccum sp.- Some species are known to cause allergic reactions. The season is from May to mid-October with only low counts. May not be a significant allergen at these levels.
Helicomyces sp.- Season is very sporadic from June to the end of September producing moderate counts. Allergenic properties unknown.
Drechslera sp.- The counts are mostly in the low range. This is a summer and fall spore, June to September. There are other related genera, which are also found in air samples, that can cause respiratory problems. One example is Bipolaris sp.
Myxomycetes- Moderate counts are observed from April to mid-October. Allergenic properties are not well known.
Last Updated: March 2015
The information presented here is designed to inform, not replace, the relationship that exists between a patient and a medical professional.