The experimental forecast program, however, incorporated daily pollen and spore counts using a special device mounted on the rooftop at Saint Mary s University to trap airborne allergens. The trapped allergens were analyzed and quantified in the lab, and correlations were made with weather and climatic conditions for the same time period. Using this information, scientists were able to combine 24-hour weather forecasts provided by MSC s Maritimes Weather Centre with the most recent pollen and spore counts to produce a daily forecast of pollen released from trees, weeds and grasses and of fungal and mould spores. The forecasts took into consideration such factors as variations in pollen release by time in the growing season, recent and expected moisture input, temperature, sunshine, and wind speed and direction. Temperature and sun are significant triggers for pollination, while high winds can lower concentrations and spread them over a larger area.
Rain can trigger the dispersal of mould spores and wash pollen out of the air.
Conditions were deemed low, medium or high, depending on concentrations of grains or spores in the air, and values for suburban and rural areas were estimated by multiplying urban values by two and four, respectively. The forecast in the summer of 2000 proved most accurate in the low category, which also occurred the most often, with diminished accuracy in the higher categories. This trend is also very common in weather forecasting, in that rare events are more difficult to predict. Environment Canada assisted with the public distribution of the forecasts via an Internet Web site and the Maritimes Weather Centre s automated telephone answering system. In addition to providing weather forecasts for the research project again this allergy season, Environment Canada is expanding its involvement to include an international literature search on other pollen and spore forecasting methods for potential use in North America.