Table 2

Timing and concentration of suspect pollens and mould spores in various geographic areas across Canada [6]

Tree pollen

Grass pollen

Weed pollen

Mould spores


British Columbia (Coastal)

• Season: early February to mid-July

• Primarily deciduous trees (alder, birch, poplar, elm, oak)

• Season: end of April to September

• Highest grass concentrations: early June to mid-July

• Not usually a major factor; no native ragweed

• Levels higher in the spring; increase further in September and October

• Most prevalent spores: Cladosporium and basidiomycetes


British Columbia (Interior)

• Season: late March to mid-July

• Primarily deciduous trees (willow, birch, poplar)

• Season starts in early May in southern parts of the province; starts up to 1 month later in northern parts

• Ragweed is minimal

• Cladosporium can occur from April to late fall


Prairies

• Season starts in the first week of April and continues through June&#8226 Main deciduous trees: birch and poplar; alder, maple, elm, oak, ash, and willow may also contribute

• Season starts in mid‐May and continues to the end of September&#8226 Peak season is usually mid‐June to early July

• Most common weeds: nettles or sage brush&#8226 Some ragweed, especially in Manitoba)

• Can occur through the spring, summer, and early fall&#8226 Alternaria and Cladosporium are the predominant moulds


Ontario and Quebec

• Season starts early April in southern Ontario and Quebec; may occur 6 weeks later in northern areas

• In southern Ontario, most common are deciduous trees (birch, poplar, oak, maple, ash, elm, mulberry, willow, chestnut, hickory)

• In northern Ontario, birch and poplar most common

• In Quebec, ash, poplar, birch most common; maple, alder and oak are less prevalent

• Season starts mid-to-late May; a couple of weeks later in northern areas

• Latter part of May and mid-June are peak seasons for grass pollination

• Ragweed season in Southern Ontario and Southwestern Quebec begins early-to-mid August

• Reaches peak in late August/early September

• Stops at first frost

• Nettle and plantain can also contribute

• Occur during spring, summer and fall months

• Concentrations may be higher late summer to fall months in Quebec

• Alternaria and Cladosporium are the predominant moulds


Maritimes

• Season in New Brunswick and Nova Scotia: late March to last week of June

• Primarily deciduous trees (birch, poplar, alder, maple, oak, and ash)

• Season: mid-May to end of September

• Peaks in early June

• Ragweed: early August to end of September

• Levels higher during the late summer and early fall months

• Alternaria and Cladosporium are the predominant moulds


Moote and Kim Allergy, Asthma & Clinical Immunology 2011 7(Suppl 1):S5   doi:10.1186/1710-1492-7-S1-S5

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