Pollen Counts in Four Canadian Cities: Geographical Variation between 2008 and 2012

Pollen grains from anemophilous plants represent an important class of aeroallergens in ambient air. High concentrations of aeroallergens, including tree and grass pollen are associated with increased asthma-related emergency department visits and hospitalizations across Canada.The geographical distribution of species of plants is dependent on multiple factors, including precipitation, soil composition and moisture and average high and low temperatures. Five “floristic zones” that support the growth of different aeroallergen-producing plants have been defined across Canada. Here we examine the differences among four Canadian cities (Vancouver, Edmonton, Winnipeg and Toronto) situated in four of the Canadian floristic zones. We describe pollen counts with respect to: start and end dates of the pollen seasons; season length; and annual pollen counts between 2008 and 2012. These cities and years were …