A Preliminary study of pollen allergies in the city of Calgary
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AbstractSeveral aspects of pollen allergy studies were investigated in ~he city of Calgary, Alberta, Canada during the period of May 1, 1987-April 27, 1988. Calgary was ideal for these studies since little information is available about the cause and treatment of pollen allergies in this area. The goals of the study were to sample and describe the pollen airload throughout the city, interpret the changes in pollen airload in relation to the environment, and describe the allergy patient population of Calgary. Prior to pollen sampling, a reference collection of pollen was compiled from the known distributions of native and introduced plants in the area. Twelve pollen categories were defined based on grain structure and size: Populus, Acer, Salix, Betula, Ulmus, Artemisia, Chenopods, Grasses, Trifolium, Medicago, Taraxacum, and Composites. Pollen was sampled in 11 locations (6 designated and 5 randomly chosen) throughout Calgary using a pollen sampler designed for this study. The new sampler is unpowered, uses acetate fibers as a collection surface, and has a design similar to a Tauber trap[Tauber, 1974]. The absolute counts from the sampling locations were analyzed by a blocked ANOVA with the time periods of sampling used as the blocking units. The counts were found to be similar in the Riverside designated site and the randomly chosen locations. These areas were then grouped together and called the Residential sampling area. The Residential area is probably the most typical pollen area for Calgary. Four other areas were identified by the ANOVA: Grassland, Developed Park, Undeveloped Park, and Business District. The different counts in these areas reflected the type and amount of local allergenic pollen producers. A typical pollen calendar for Calgary was defined using the Residential area counts. The early Spring season pollinators in Calgary were Acer and Populus. Betula and Salix did not appear until May and Ulmus never had a true peak period. All tree pollen in the air decreased greatly after May. During the Summer, Grasses, Chenopods and Artemisia were the most significant pollen types . The weather patterns during the 1 year sampling period were compared to the pollen counts of the 5 areas. A temperature increase to between 5°C and 15°C was found to be necessary for at least 2 weeks prior to tree pollination. Weed and grass pollen appeared after at least 2 weeks of moderate temperatures of 10°C to 15°C. It was probably the combined effect of increased photoperiod and warmer temperatures which caused the pollination. Precipitation did not seem to decrease pollen counts in all areas. The pollen sampler's efficiency in wet conditions may, however, have obscured these findings. Wind direction did correlate with higher counts when the wind came from a direction where it encountered many pollen producers. The allergy patient population in Calgary was found to be normally distributed. There was some indication that a positive skin test reaction to any tree or grass pollen could correlate with sensitivities to other tree or grass extracts. The patient survey indicated that the 12 allergenic pollen categories contributing to the airload in Calgary should be emphasized in skin tests for pollen allergies. The continued monitoring of Calgary pollen airloads would also assist in improving the treatment and detection of pollen allergies in Calgary.
Bibliography: p. 108-112.