Allergen Update
Toronto, Ontario (Brampton area)
Predominant pollen:
The tree pollen seasons can fluctuate from year to year by as much as two weeks at this site. The pollen seasons described here try to cover the time when each can occur.
Acer sp.- Maple season varies due to the number of species present and the effect of weather. Significant counts, in the moderate range, are observed from the end of March to mid-May.
Alnus sp.- Alder season occurs mostly in April and the counts vary from low to moderate with the occasional high counts. The fluctuation in the season is due to the number of species present and the effect of weather.
Betula sp.- The birch season can occur from mid-April to early June with some very high counts observed. The birch look-a-likes' season has significant counts for approximately two weeks and can occur from mid-April to about mid-May.
Populus sp.- The poplar and aspen season is from late March to the end of April. Some of the counts are high and may cause allergic reactions.
Cupressaceae group- The cedars, junipers and yews produce moderate and high counts during the month of April.
Fraxinus sp.- The ash pollination season is April to late May. High counts are observed and they are considered to be allergenic only in highly sensitized individuals.
Pinaceae group- This group includes the spruce, fir and pine trees. High counts are observed from May to late June. The time of the season can vary from year to year by as much as two weeks.
Quercus sp.- The oaks have two distinct seasons. The first pollination is short and occurs from mid to late April, the main season, which produces the most pollen, occurs in May. The oaks are considered to be highly allergenic.
Ulmus sp.- The elm are important allergens. The season lasts approximately two weeks and can occur from late March to late April and moderate counts are observed.
Salix- The willow season is from mid-April to mid-May with moderate and high counts.
Morus- Mulberry season lasts between two to three weeks and can occur from early May to early June, moderate and high counts are observed.
Gramineae- The grasses produce significant pollen counts from the end of May to the end of July. The season starts early May and lasts until the end of October.
Ambrosia sp.- Ragweed pollen is observed from mid-July until mid to late October with the highest counts occurring the second week in August to mid-September.
Urtica sp.- Nettles occur in significant numbers that may cause allergic reactions and the season is July and August.
Predominant spores:
Diatrypaceae sp.- The counts are sporadic throughout the whole counting season. High counts can be observed from late March to mid-October.
Leptosphaeria sp. & Leptosphaeria look-a-likes- These two are grouped together since they are in the same class of fungi and are similar microscopically. The season is mid-May to mid-September with great fluctuations in counts from day to day. This is probably due to the effect of weather. Moderate counts are observed in July and August.
Erysephe (Oospora)- Powdery mildew - The season is from June to early October. Mostly moderate counts are observed.
Boletus sp.- The season for this spore is very sporadic with some very high counts observed. It may be of significance in causing allergic reactions. The season is late June to mid-October.
Coprinus sp.- This mushroom can produce some moderate and high counts from late May to mid-October. It is considered an important allergen.
Ganoderma sp.- The bracket fungus can produce very high counts from June to mid-September. It is considered an important allergen.
Uredinales- The rusts do not occur in really high numbers and not enough is known if they are of significance in causing allergic reactions at these levels. The season is from June to late October.
Ustilaginales- The smuts can reach high counts, allergenicity is unknown. The season is May to mid-October with some high counts.
Alternaria sp.- The counts do get high and some species are known to cause allergic reactions. The season is from May to mid-October.
Penicillium & Aspergillus sp.- These spores are found throughout the whole counting season and are probably present in significant numbers beyond that. The highest counts are observed from July to late fall.
Botrytis sp.- This may be a significant allergen although the counts do not get very high. The season is July to the end of September.
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.
Epicoccum sp.- Some species are known to cause allergic reactions and the season is from the June to mid-October with some high counts.
Fusarium sp.- Counts are very sporadic throughout the whole counting season. The majority of the season occurs from May to mid-October with some high counts.
Helicomyces sp.- Season is from May to the end of September producing moderate and high counts. The season is very sporadic.
Pithomyces sp.- Season is mostly in the moderate range from July to the end of September.
Polythrincium sp.- Allergenicity is unknown but significant counts are observed from July to the end of September.
Torula sp.- Some species are known to cause allergic reactions. Moderate counts are observed from August to late October. Season is sporadic.
Myxomycetes- Moderate counts are observed from August to late September.
Last Updated: 08-October-2003
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