ANALYSIS OF METEOROLOGICAL VARIABLES AND SEASONAL AEROALLERGEN POLLENCOUNTS IN DENVER, COLORADO

Background: The observation of low levels of weed pollens following a freeze and an early autumn snowfall in Denver, Colorado led to this an alysis of meteorologic variables and pollen counts. Objective: The pur pose of this study was to examine, in depth, the relationship between observed pollen counts and a selection of independent meteorologic var iables. Methods: We prospectively studied in 1991 daily high and low t emperature, relative humidity, precipitation, barometric pressure, per cent sunshine, wind velocity and direction, tree, grass, and weed poll en, as well as dates of the first frost/freeze. Similar data were retr ospectively analyzed for 1987-1990. Results: Correlation coefficients for the prospective data were as high as .611 for high temperature and cottonwood and .718 for high temperature and maple (P < .001). High a nd low temperature showed strong correlations with the combined weed c ounts (.598 and .628, respectively, P < .001). Conclusions: Denver wee d pollens appear impacted more by temperature and less by precipitatio n and humidity, while the converse is true for tree and grass pollen. However, weed pollen, especially sage, may appreciably rebound after f reezing temperatures. While separate meteorologic variables may have h igh correlations with specific pollen counts in a given year, such eff ect is not consistent and varies from year to year.