lbl_titreOutdoorsAllergens

Grass can be found almost everywhere and, although there are more than 1,200 species of grass growing in North America, most of them do not cause allergies.

Grasses that are a common source of allergies include:

• Bermuda grass: a lawn or pastural grass that can also be found growing in the cracks of sidewalks
• Kentucky blue grass: a pastural grass with bluish-green leaves
• Johnson grass: a very tall perennial grass that grows in excess of two meters in height
• Timothy grass: a tall grass often grown for cattle forage or for making hay

Other grasses known to cause allergies are:

• Bahia
• Orchard
• Meadow fescue
• Ryegrass
• Redtop
• Sweet vernal

Ragweed refers to a group of about 15 species of weed plants.

Short ragweed (sometimes referred to as “Common ragweed”) flourishes along roadsides and produces enormous amounts of airborne pollen. In fact, one plant can generate 1 billion grains of pollen that can travel more than 100 miles.

Short ragweed is called the “king” of allergenic plants because it is the most prevalent species of ragweed and the most important cause of seasonal allergy symptoms in America.

How to keep Ragweed in check? Keep doors or windows closed and pay attention to pollen count variations in your area.

Other allergy-triggering weeds are:

• Dock
• Goldenrod
• Plantains
• Sheep sorrel
• Russian thistle
• Sagebrush
• Nettles

Fluctuations in daily temperature, rain and sun can also affect the amount of pollen released by trees during the pollen season.

Some species of trees cause allergies more than others.

• Alder: many people with tree pollen allergies are allergic to this species, found throughout most of North America.
• Box elder: a member of the maple family that is abundant in Quebec, Ontario and the western provinces except British Columbia. Other species of maple trees cause fewer allergy problems.
• Birch: it is known to produce large amounts of pollen and is a common source of allergy troubles.
• American elm: widespread in Canada from western Newfoundland to Saskatchewan, this species can cause severe allergies in some people.
• Mulberry: the Red mulberry, widespread in southern Ontario has been known to cause severe hay fever symptoms.
• Oaks: shed more pollen than any other tree and are an important source of allergies. They are found throughout Canada with many species in Ontario, Quebec and the Maritimes.

Fortunately, there are many trees around us unlikely to cause allergy problems, either because they don’t usually produce enough pollen or because fewer people are allergic to these trees:

• Ash
• Beech
• Chestnut (not including Horse chestnut)
• Maple (not including Box elder)
• Poplar, aspen and cottonwood
• Willow
• Fir, pine and spruce
• Hazel
• Hickory