Allergen Update

Ottawa, Ontario

Predominant pollen:

The tree pollen seasons can fluctuate from year to year by as much as two to three weeks at this site due to the effect of weather. The pollen seasons described here try to cover the time when each can occur.

Acer sp.- The maple season flutuates due to the number of species present and the effect of weather. There is a short early season that can occur from mid to late March. The main season can start from late March to almost mid-April and end mid-May to early June. Mostly low and moderate counts are observed with the occational high counts. Some species are known to cause allergic reactions.

Alnus sp.- There is a short early season that can occur from the second week of March to the end of March. The main season can start late March to the second week of April and end early to late June. Some high counts can be observed and can cause allergic reactions. The season can vary from year to year in counts and when the season occurs due to the effect of weather.

Betula sp.- The birch season can start from mid to late April and end late May to mid-June. The start and end of the season can vary from year to year by as much as two weeks based on the effect of weather. Some very high counts are observed. They are considered important allergens.

Birch look-a-likes sp.- Birch look-a-likes' season can vary in length as well as the amount of pollen observed. Some years are low while other years can produce moderate counts. Some species are considered allergenic. The season occurs in May.

Castanea sp.- The chestnut seasons vary from year to year. The season can start the second week of May to early June and end the first to last week of June. Most years only low counts are observed but moderate counts are also possible but rare.

Carya sp.- The hickory season can vary in length from one to three weeks. The seasons fluctuate a great deal from year to year. The season can start from the first week to the third week of May and end early to mid-June. The counts are mostly in the low range with some moderate counts observed some years.

Tsuga sp.- The hemlock season can vary in the amount of pollen produced, season length and when the season starts and finishes. This is due to cyclical patterns and the effect of weather. The season can start from early to late May and end late May to mid-June. Mostly low counts are observed, but the occational moderate counts are possible.

Populus sp.- The poplar, cottonwood and aspen season can start the third week of March to early April and end early to late May. High counts are observed and allergic reactions can occur at these levels.

Cupressaceae family- The cedar, juniper, and yew season can start early to late March and end late May to mid-June. Some very high counts are observed but most species in Canada are not considered allergenic.

Tilia sp.- The linden and basswood season varies a great deal from year to year. Some years only low counts are observed while other years moderate counts are possible. The season can start the third week of June to the second week of July and end mid to late July. The length of the season also varies from year to year.

Fraxinus sp.- The ash pollen season can start early April during warm springs like 2010 and 2012. Generally the season start is from mid-April to early May and ends mid-May to early June. Some very high counts are observed. They can cause allergic reactions in highly sensitised individuals.

Pinaceae family- High counts are observed throughout the pollen season. The season start is generally from late April to the second week of May and ends early to mid-July. The pollen may cause reactions in highly sensitized individuals.

Quercus sp.- The season can start the first week of April to the first week of May and end late May to mid-June. The season can vary as to when it starts but also how much pollen is produced. This is mostly due to the effect of weather. High counts are observed and some species can cause allergic reactions.

Fagus sp.- The season for the beech trees varies a great deal from year to year. Some years hardly any pollen is produced while other years moderate counts are possible. Generally only low counts are observed. The season can last from one week to over a month. Season start can occur from the first to the third week of May and end the third week of May to the second week of June. They may not cause reactions except in highly sensitized individuals.

Salix sp.- The willows may cause allergic reactions in highly sensitized individuals. The season can start mid to late April and can end late May. Mostly low and moderate, with occational high, counts are observed.

Ulmus sp.- The elm are important allergens. The season is highly affected by weather. The season can start mid-March to early April and end late April to mid-May. The amount of pollen released can vary from year to year and some years high counts are observed.

Morus sp.- The mulberry season can last almost a month. The season can start mid-April to early May and end late May to early June. Mostly low, with the occational moderate, counts are observed. Can be considered allergenic in idividuals who are highly sensitized.

Gramineae family- The grass season can start from early to mid-May and end mid-September to early October. Moderate and high counts are observed from mid-May to late July.

Ambrosia sp.- Ragweed pollen is observed starting the last two weeks of July with the high counts occurring from August to late September. Low pollen counts are observed until late October.They are considered to be highly allergenic.

Urticaceae sp.- The nettles and parietaria occur in significant numbers that may cause allergic reactions. The season can start early to mid-June and ends late September. Mostly low and moderate counts are observed. Important allergens due to their small size.

Plantago sp.- The plantains can be of significance in causing allergic reactions. The season can start early to mid-June and end the second to last week of September. Only low counts are observed.

Predominant spores:

Diatrypaceae sp.- The spore counts are sporadic throughout the whole counting season. High counts can be observed from March to well into October. They are not known to cause allergic reactions.

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 is May to mid-October with great fluctuations in counts from day to day. This is probably due to the effect of weather. The counts are in the moderate and high range. The look-alikes produce some very high counts.

Erysiphe (Oospora) sp.- Powdery mildew - The season, with moderate and high counts, occurs from April to mid-October.

Caloplaca sp.- Moderate counts are observed from August to mid-October. The season is sporadic. May not be an important allergen.

Boletus sp.- The counts for this spore do not get very high but may be of significance in causing allergic reactions. The season is sporadic and occurs from mid-June to mid-October.

Coprinus sp.- This mushroom can produce moderate and high counts from early May to late October. Considered an important allergen.

Ganoderma sp.- This bracket fungus can produce very high counts from June to late October. Considered an important allergen.

Uredinales sp.- The rusts do not occur in really high numbers, but not enough is known about their significance in causing allergic reactions at these levels. The season is from mid-May to late October.

Ustilaginales sp.- The smuts can reach high counts, allergenicity is unknown. The season is mid-May to late October.

Alternaria sp.- Some of the counts are really high throughout the season and some species are known to cause allergic reactions. The season is from March to late October. The highest counts occur from late May to late October.

Penicillium sp. & Aspergillus sp.- These spores are found throughout the whole counting season and are probably present in significant numbers beyond that. The moderate and high counts are observed from late March to late fall.

Botrytis sp.- This may be a significant allergen even though the counts do not get very high. The season is from late May to mid-October.

Cladosporium sp.- The most abundant spore found throughout the whole season. This spore exists all year round and very high counts are known to occur from March to late fall.

Epicoccum sp.- Found in high numbers and some species are known to cause allergic reactions. The season is from March to late fall. The high counts occur from mid-June to late October.

Fusarium sp.- Counts are very sporadic throughout the whole counting season. The season occurs from March to mid-October.

Helicomyces sp.- Season is from May to mid-October producing moderate and high counts. The season is very sporadic.

Pithomyces sp.- Season with high to low counts is from July to mid-October.

Torula sp.- Some species are considered allergenic. Moderate counts are observed from July to early October.

Polythrincium sp.- Allergenicity is unknown but significant counts are observed from July to mid-October.

Myxomycetes- Moderate counts are observed from August to mid-October.

Last Updated : 3 March 2015

The information presented here is designed to inform, not replace, the relationship that exists between a patient and a medical professional.

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