SURVEYS OF AIR-BORNE RAGWEED POLLEN IN CANADA WITH PARTICULAR REFERENCE TO SITES IN ONTARIO

Abstract

Results from 164 pollen collecting stations across Canada indicate that the heaviest concentration of ragweed pollen in the air is in southern Ontario and Quebec. The northern limits of this heavy ragweed pollen concentration extend from the base of the Bruce Peninsula to the St. Lawrence River about midway between the mouth of the Saguenay River and Quebec City. Zones of different intensities of air-borne ragweed pollen in Ontario are determined from investigations initiated in 1950.