Allergy season is here and you can blame all your sneezing on pollen. Check out which places are the most allergic in Canada.

Sneezing yet? Blame pollen. From spring till early fall, Mother Nature unleashes this powdery substance from trees, then grass and, finally, ragweed, making life a sniffling, itchy-eyed misery for allergy sufferers. To make matters worse, if you happen to live in a large urban area, smog can amplify your discomfort. Find out which parts of the country are worst for tree, grass and ragweed allergies.

Tree Pollen
The biggest culprit is birch, mainly affecting British Columbia, southern  Ontario, Quebec, the Atlantic provinces and as far north as Yellowknife in the Northwest Territories, but other offenders include alder, oak, maple and box elder. Because of the city's milder temperatures, Vancouver gets a head start on tree-pollen season; in southern Ontario, the impact can be felt as early as mid-March and can linger until May.

Smog Alert
Pollen isn't the only irritating substance that comes out to play in warmer temperatures—smog is also a concern. "Smog is an accumulation of toxins, particles and humidity," says Bryce Wylde, alternative health practitioner and associate medical director of P3, a Toronto integrative health-care facility. "You get this big toxic cloud that amplifies the allergic reaction." Not surprisingly, smog is almost always a big-city problem, impacting people in Vancouver, Calgary, Edmonton, Toronto, Montreal, Quebec City, Halifax and St. John's, N.L.

Grass Pollen
If you live in the Prairie provinces, prepare to get hit with this seasonal sniffler from mid-May to late September. For the rest of the country, grass pollen is associated only with the summer months (mainly, June and July).

Ragweed
This annual annoyance strikes primarily southern Ontario and western Quebec from August to late September. "There is very little ragweed in the Prairie and Atlantic provinces," says Dr. Sandy Kapur, president of the Canadian Society of Allergy and Clinical Immunology in Halifax.